[Federal Register: January 16, 2008 (Volume 73, Number 11)]
[Rules and Regulations]
[Page 3145-3179]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16ja08-21]
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Part III
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Final Rule To List Six
Foreign Birds as Endangered; Final Rule
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R1-JA-2008-007; 96100-1671-000; 1018-AT62]
Endangered and Threatened Wildlife and Plants; Final Rule To List
Six Foreign Birds as Endangered
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
endangered status for six avian species--black stilt (Himantopus
novaezelandiae), caerulean paradise-flycatcher (Eutrichomyias rowleyi),
giant ibis (Pseudibis gigantea), Gurney's pitta (Pitta gurneyi), long-
legged thicketbird (Trichocichla rufa), and Socorro mockingbird (Mimus
graysoni)--under the Endangered Species Act of 1973, as amended (Act).
This rule implements the protection of the Act for these six species.
EFFECTIVE DATE: This final rule is effective February 15, 2008.
ADDRESSES: The supporting file for this rule is available for public
inspection, by appointment, during normal business hours, Monday
through Friday, in Suite 110, 4401 N. Fairfax Drive, Arlington,
Virginia 22203.
FOR FURTHER INFORMATION CONTACT: Dr. Patricia De Angelis, at the above
address; by fax to 703-358-2276; by e-mail to
ScientificAuthority@fws.gov; or by telephone, 703-358-1708.
SUPPLEMENTARY INFORMATION:
Background
In this final rule, we determine endangered status for six foreign
bird species under the Act (16 U.S.C. 1531 et seq.): Black stilt
(Himantopus novaezelandiae), caerulean paradise-flycatcher
(Eutrichomyias rowleyi), giant ibis (Pseudibis gigantea), Gurney's
pitta (Pitta gurneyi), long-legged thicketbird (Trichocichla rufa), and
Socorro mockingbird (Mimus graysoni).
Previous Federal Action
Section 4(b)(3)(A) of the Act requires us to make a finding (known
as a ``90-day finding'') on whether a petition to add, remove, or
reclassify a species from the list of endangered or threatened species
has presented substantial information indicating that the requested
action may be warranted. To the maximum extent practicable, the finding
shall be made within 90 days following receipt of the petition and
published promptly in the Federal Register. If we find that the
petition has presented substantial information indicating that the
requested action may be warranted (a positive finding), section
4(b)(3)(A) of the Act requires us to commence a status review of the
species if one has not already been initiated under our internal
candidate assessment process. In addition, section 4(b)(3)(B) of the
Act requires us to make a finding within 12 months following receipt of
the petition on whether the requested action is warranted, not
warranted, or warranted but precluded by higher-priority listing
actions (this finding is referred to as the ``12-month finding'').
Section 4(b)(3)(C) of the Act requires that a finding of warranted but
precluded for petitioned species should be treated as having been
resubmitted on the date of the warranted but precluded finding, and is
therefore subject to a new finding within 1 year and subsequently
thereafter until we take action on a proposal to list or withdraw our
original finding. The Service publishes an annual notice of resubmitted
petition findings (annual notice) for all foreign species for which
listings were previously found to be warranted but precluded.
On November 24, 1980, we received a petition (1980 petition) from
Dr. Warren B. King, Chairman, United States Section of the
International Council for Bird Preservation (ICBP), to add 79 bird
species (19 native and 60 foreign) to the List of Endangered and
Threatened Wildlife (50 CFR 17.11(h)), including the black stilt and
the long-legged thicket bird (or, long-legged warbler, which was the
common name used in the petition). In response to the 1980 petition, we
published a positive 90-day finding on May 12, 1981 (46 FR 26464), for
77 of the species (19 domestic and 58 foreign), noting that 2 of the
foreign species identified in the petition were already listed under
the Act, and initiated a status review. On January 20, 1984, we
published an annual review on pending petitions and description of
progress on all petition findings addressed therein (49 FR 2485). In
that notice, we found that listing all 58 foreign bird species from the
1980 petition, including the black stilt and the long-legged
thicketbird, was warranted but precluded by higher-priority listing
actions. On May 10, 1985, we published the first annual notice (50 FR
19761) in which we continued to find that listing all 58 foreign bird
species from the 1980 petition was warranted but precluded. In our next
annual notice, published on January 9, 1986 (51 FR 996), we found that
listing 54 species from the 1980 petition, including the black stilt
and the long-legged thicketbird, continued to be warranted but
precluded, whereas new information caused us to find that listing four
other species in the 1980 petition was no longer warranted. We
published additional annual notices on the species included in the 1980
petition on July 7, 1988 (53 FR 25511); December 29, 1988 (53 FR
52746); April 25, 1990 (55 FR 17475); and November 21, 1991 (56 FR
58664), in which we indicated that the black stilt and the long-legged
thicketbird continued to be warranted but precluded.
On May 6, 1991 (1991 petition), we received a petition from Alison
Stattersfield, of ICBP, to list 53 additional foreign birds under the
Act. The caerulean paradise-flycatcher, giant ibis, Gurney's pitta, and
Socorro mockingbird were included in the 1991 petition. On December 16,
1991, we published a positive 90-day finding and announced the
initiation of a status review of the 53 foreign birds listed in the
1991 petition (56 FR 65207). The 1991 petition included the giant ibis,
Gurney's pitta, Socorro mockingbird, and caerulean paradise-flycatcher
among the 53 foreign birds that the petitioner requested be listed
under the Act. On March 28, 1994 (59 FR 14496), we published a proposed
rule to list 30 African bird species from both the 1980 and 1991
petitions. In the same Federal Register document, we included a notice
of findings in which we announced our determination that listing the 38
remaining species from the 1991 petition was warranted but precluded;
this group included the giant ibis, Gurney's pitta, Socorro
mockingbird, and caerulean paradise-flycatcher. On May 21, 2004 (69 FR
29354), we published an annual notice of findings on resubmitted
petitions for foreign species and annual description of progress on
listing actions (2004 annual notice) within which we ranked species for
listing by assigning them a Listing Priority Number per the Service's
listing priority guidelines, published on September 21, 1983 (48 FR
43098). Based on this ranking and priorities, we determined that
listing five of the previously petitioned species--the black stilt,
caerulean paradise-flycatcher, giant ibis, Gurney's pitta, and Socorro
mockingbird--was warranted. In the same 2004 annual notice, we
determined that the long-legged thicketbird and 16 other species no
longer warranted listing on the basis that those species were likely
extinct. In response to the 2004 annual notice, we
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received information indicating that the long-legged thicketbird had
been rediscovered, in small numbers, in 2002. The magnitude of the
threat to the species was perceived as high and the immediacy of threat
imminent. Therefore, we assigned this species a listing priority
ranking of 1, which ranking is reserved specifically for a monospecific
genus, and determined that listing the species was warranted at that
time.
On November 22, 2006 (71 FR 67530), we published a Federal Register
notice to list black stilt, caerulean paradise-flycatcher, giant ibis,
Gurney's pitta, long-legged thicketbird, and Socorro mockingbird as
endangered. We implemented the Service's peer review process and opened
a 60-day comment period to solicit scientific and commercial
information on the species from all interested parties following
publication of the proposed rule.
Summary of Comments and Recommendations
In the proposed rule of November 22, 2006 (71 FR 67530), we
requested that all interested parties submit information that might
contribute to development of a final rule. We received five comments:
two from members of the public and one each from the governments of
Cambodia, Fiji, and Mexico. In accordance with our policy, ``Notice of
Interagency Cooperative Policy for Peer Review in Endangered Species
Act Activities,'' published on July 1, 1994 (59 FR 34270), we also
sought the expert opinion of at least three appropriate independent
specialists regarding the proposed rule.
Comment 1: Four commenters supported the proposed listings,
including the governments of Cambodia, Fiji, and Mexico. The government
of Cambodia ``strongly endorsed[d] the proposal of giant ibis to be
listed in [the] U.S. Endangered Species Act. The Fijian government
noted that the benefits of listing the long-legged thicketbird under
the Act are ``perhaps marginal'' but that a listing could help where
species, such as the thicketbird, are not listed in the Appendices of
the Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES) because trade in the wild bird is not a concern
at this time. The potential funding and technical support (see
Available Conservation Measures) for the development of management
programs for the conservation of species in foreign countries could be
beneficial to the thicketbird in Fiji. Similarly, the government of
Mexico commented that listing the Socorro mockingbird under the Act
would support its ongoing efforts and additional actions to be
undertaken by the Mexican government, including scientific
investigations, in order to protect the species.
Our Response: While general support of a listing is not, in itself,
a substantive comment that we take into consideration as part of our
five-factor analysis, we appreciate the support of these range
countries. Cooperation is important to the conservation of foreign
species.
Comment 2: One researcher opposed the listing of the long-legged
thicketbird on the basis that the species is not endangered, but merely
elusive to the inexperienced or to those with an uneducated eye.
Our Response: We have taken into account in our review of the long-
legged thicketbird the bird's elusive behavior. However, we believe
that we have used the best available scientific information in our
status review and have accurately determined the appropriate threat
status for this species.
Comment 3: One commenter recommended that the term kak[iuml] be
used to refer to the black stilt throughout the rule, as it is the
preferred name in New Zealand.
Our Response: We have added this common name in the species
description for the black stilt, but have chosen to use the common name
``black stilt'' throughout the rule and in the list because the federal
listing will be categorized under the species grouping ``stilt.''
Several commenters provided additional information on the species.
This information has been considered and incorporated into the
rulemaking as appropriate (as indicated in the citations by ``in
litt.'').
Species Information and Factors Affecting the Species
Under section 4(a) of the Act (16 U.S.C. 1533(a)(1)) and
regulations promulgated to implement the listing provisions of the Act
(50 CFR part 424.11), we may list a species as threatened and
endangered on the basis of five threat factors: (A) Present or
threatened destruction, modification, or curtailment of its habitat or
range; (B) overutilization for commercial, recreational, scientific, or
educational purposes; (C) disease or predation; (D) inadequacy of
existing regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence. Listing may be warranted based on
any of the above threat factors, either singly or in combination.
Under the Act, we may determine a species to be endangered or
threatened. An endangered species is defined as a species which is in
danger of extinction throughout all or a significant portion of its
range. A threatened species is defined as a species which is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. Therefore, we evaluated the
best available scientific and commercial information on each species
under the five listing factors to determine whether they met the
definition of endangered or threatened.
Following is a species-by-species analysis of these five factors.
The species are considered in alphabetical order: Black stilt,
caerulean paradise-flycatcher, giant ibis, Gurney's pitta, long-legged
thicketbird, and Socorro mockingbird.
I. Black stilt (Himantopus novaezelandiae)
Species Description
The black stilt is a wading bird in the family Recurvirostridae. It
is native to New Zealand and is locally known there by its Maori name
``kaki.'' Adults are characterized by long red legs, a slender bill and
black plumage (BirdLife International (BLI) 2007a; New Zealand
Conservation Management Group (NZ CMaG 2007). Adult males and females
are generally regarded as having identical plumage (BLI 2007e);
however, Elkington and Maloney (2000) determined that white flecking
around their eyes and crown is generally indicative of older males.
Juveniles have a white-plumed breast, neck, and head (BLI 2007e). Black
and pied stilt (Himantopus himantopus) hybridize (see Taxonomy, below),
and hybrids are more varied in color, with varying gradations of white
and black plumage, and varying body characteristics, such as shorter
legs and longer bills (BLI 2007e; Department of Conservation (DOC)
2007a; Maloney & Murray 2002; Reed et al. 2007).
The species can reach 16 inches (in) (40 centimeters (cm)) (BLI
2007e) in height, with a wingspan of 23 in (58 cm). The average age of
birds in the current population is 6 years (BLI 2007e; Maloney & Murray
2002). The potential lifespan of the species is unknown, but the oldest
recorded specimen, a banded female relocated in 1983, was estimated to
be at least 12 years old (Pierce 1986b).
Taxonomy
The black stilt was first taxonomically described by Gould in 1841
and placed in the family Recurvirostridae. It is one of two stilt
species in New Zealand, the other being the pied stilt (Pierce 1984a;
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Reed et al. 1993a). Where their ranges overlap, the black stilt may
interbreed with its close relative, the pied stilt (Reed et al. 1993a).
It is generally accepted that hybridization between these two species
has been occurring only in the last two centuries, as the pied stilt
expanded its range from Australia to New Zealand in the early 19th
century (Greene 1999; Pierce 1984a; Reed et al. 1993a). During the late
19th century, the frequency of hybrid sightings increased (Pierce
1984b) but observers of the time did not realize that the two species
were hybridizing, and the taxonomy of Himantopus species of New Zealand
was the subject of much debate (Buller 1874; Potts 1872; Travers 1871).
In 1984, Pierce (1984b) concluded on the basis of morphological,
ecological, and behavioral differences that the two species remained
distinct. Genetic analysis in the 20th century confirmed that the two
species were undergoing introgressive hybridization, wherein viable
offspring produced from the successful mating of two distinct species
were subsequently capable of mating with parental species (Greene
1999). From these studies, despite the genetic similarity between the
two species, Greene (1999) concluded that the species remain distinct.
Habitat and Life History
Black stilt habitat includes riverbanks, lakeshores, swamps, and
shallow ponds (Maloney & Murray 2002; Pierce 1982; Potts 1872; Reed et
al. 1993a). The species' habitat preferences shift slightly depending
on the seasons, which are: Breeding (braided rivers, side streams, and
swamps), post-breeding (riverbeds and shallow tarns), and wintering
(inland waters or river deltas) (Maloney & Murray 2002). However, these
habitats are often located within the same watershed, and the species
is considered a primarily sedentary, nonmigrating species (Maloney &
Murray 2002; Pierce 1986b). About 90 percent of the black stilt
population overwinters in the Upper Waitaki Basin (UWB; in the central
region of the South Island) by moving to inland areas to continue
feeding on aquatic insects, including larvae of mayfly (Deleatidium
sp.) and caddisfly (Olinga sp.), and, to a lesser extent, on mollusks
and fish (DOC 2007a; Reed et al. 1993a). Researchers believe that the
black stilt's long legs allow them to wade out into the deeper,
unfrozen sections of rivers where they can continue foraging throughout
the winter (DOC 2007a; Reed et al. 1993a).
A small percentage (about 10 percent) of the population migrates to
coastal Canterbury on South Island or Northern Island coastal areas in
the winter, from February to June, before returning to the UWB to breed
in July and August (BLI 2007e; Maloney & Murray 2002: NZ CMaG 2007;
Pierce 1984a; Pierce 1996; Reed et al. 1993a). Reed et al. (1993a)
believe that this migratory behavior has resulted from hybridization
with the pied stilt (which migrates to coastal waters in the winter)
(Dowding & Moore 2006). In the absence of a suitable mate of the same
species, black stilts will mate and produce hybrid offspring with the
pied stilt (BLI 2007e; DOC 2007a; Maloney & Murray 2002; Reed et al.
1993a). Mixed pairs (a black stilt paired with a pied stilt) and their
offspring are more likely to participate in migratory behavior (Dowding
& Moore 2006; Reed et al. 1993a). Hybridization is discussed further
under Factor E.
Black stilts reach adulthood around 18 months of age, attaining
sexual maturity between 2 and 3 years of age. They mate for life, nest
in solitary pairs (often miles (kilometers) from another pair), and
exhibit high nesting fidelity (returning to the same location to nest
each year) (BLI 2007e; DOC 2007a; Maloney & Murray 2002; Pierce 1984a;
Reed et al. 1993a). The breeding season begins in July or August and
egg-laying occurs from September to December (BLI 2007e; Maloney &
Murray 2002; NZ CMaG 2007). Ground-nesting birds, black stilts prefer
open nesting sites, such as dry, stable riverbanks (Maloney & Murray
2002; Pierce 1982; Pierce 1986b; Reed et al. 1993a). They lay a typical
clutch size of four eggs and have a lengthy fledging period of 40 to 55
days (the amount of time it takes birds to hatch and leave the nest)
(Maloney & Murray 2002). Both sexes share the nesting responsibility
(Maloney & Murray 2002; Pierce 1986b; Pierce 1996; Sanders & Maloney
2002). Eggs are incubated by both sexes for 25 days, and pairs will
often re-nest if the first clutch is lost early in the season (BLI
2007e; Reed et al. 1993a; Maloney & Murray 2002; NZ CMaG 2007). Chicks
are precocial (the young are relatively mature and mobile from the
moment of hatching) and capable of feeding themselves within hours of
hatching (DOC 2007a; Reed et al. 1993a). After fledging, chicks stay
with parents until the beginning of the following breeding season
(Maloney & Murray 2002).
The black stilt's breeding success in the wild is very low. For
example, according to Maloney and Murray (2002), from 1977 to 1979, of
33 chicks that hatched in unmanaged nests, only 2 individuals (or 6.1
percent) survived to fledge (i.e., lived long enough to leave the
nest). Overall breeding success (nesting success plus fledging success)
for the same period was 0.9 percent. Recruitment, defined by Maloney
and Murray (2002) as the number of chicks attaining 2 years of age, is
only about 4 percent.
Reproductive potential does not appear to be the primary limiting
factor to the black stilt's breeding success and recruitment rates. The
black stilt has high reproductive capability, first reproducing at age
2 and continuing to produce multiple clutches in captivity to at least
age 13 plus (Maloney & Murray 2002; Reed 1998). The species has high
fecundity, producing clutches of one to four eggs every breeding
season, and will re-nest if clutches are lost early in the season (BLI
2007e; Reed et al. 1993a; Maloney & Murray 2002). Moreover, a review of
captive breeding records from two breeding seasons (1981 to 1982 and
2001 to 2002) found that the survival rate of captive-bred stilts
reintroduced to the wild at 2 months and 10 months increased to 88
percent and 82 percent, respectively (Van Heezik et al. 2005).
Historical Range and Distribution
When it was described in 1841, the species' range included both the
North and South Islands of New Zealand (Pierce 1984a). Its range has
contracted twice in the 20th century: Once in the 1940s, when the
breeding range became restricted to the South Island, and again in the
1960s, when the UWB became their only breeding area (Maloney & Murray
2002; Pierce 1984a; Reed et al. 1993a).
As the black stilt's range contracted, researchers noticed that the
pied stilt's range had increased (Pierce 1984a). In the last quarter of
the 19th century, both black and pied stilts were considered common
across South Island (Buller 1874, 1878; Travers 1871). By the 1980-1981
breeding season, the estimated number of pied stilts in the UWB was
between 1,500 and 2,000 (Pierce 1984a). At the same time, only 23 black
stilt adults were known in the wild (Maloney & Murray 2002; Van Heezik
et al. 2005). Experts considered whether the black stilts were being
competitively excluded by the pied stilt and found that this was not
the case. Black stilts and pied stilts prefer slightly different
feeding areas (black stilts forage in riffles and pied stilts at pools)
(Pierce 1986a); black stilts are better foragers than pied stilts
(employing a greater variety of foraging techniques that allow them to
obtain more food) (DOC 2007a; Pierce 1986a; Reed et al. 1993a); also,
black stilts are territorially dominant over pied stilts when breeding
areas overlap (Maloney & Murray 2002). From
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this work, researchers concluded that the decreasing range and numbers
of black stilts in the face of the increasing pied stilt population
reflected the black stilt's inability to adapt as readily to man-
induced changes, namely, the introduction of predators and habitat
modification (Pierce 1986a, 1986b; Maloney & Murray 2002: Reed et al.
1993a). Historical declines were attributed primarily to predation by
mammals introduced in the 19th century and secondarily to habitat loss
and hybridization with the pied stilt (Pierce 1984b; Reed et al. 1993a,
1993b).
For a primarily sedentary species, the black stilt requires a
fairly large area for feeding and nesting. In counts conducted between
1991 and 1994, Maloney (1999) found less than one black stilt for every
3 mi (5 km) of river surveyed. The species' tendency to overwinter
inland requires sufficiently large areas of river habitat to allow for
continuous year-round feeding (DOC 2007a; Reed et al. 1993a). Life
history traits, such as lifelong pair-bonding combined with high
nesting fidelity (returning to the same location to nest each year) and
solitary nesting combined with their preference for open nesting sites
(often miles from another pair), contribute to the highly dispersed
nature of the population and their resultant large habitat requirement
(Maloney & Murray 2002; Pierce 1982, 1986b; Reed et al. 1993a).
Current Range and Distribution
The current range of the black stilt is estimated to be an 821
square mile (mi\2\) (2,830 square kilometer (km\2\)) area in the
``braided-river'' habitat of the UWB (BLI 2007e). Located on the
eastern side of the Southern Alps, in central South Island, New
Zealand, the following rivers and lakes comprise the braided river
habitat: Tasman, Godley, Hopkins, Ahuriri, Tekapo, Cass, Dobson,
Macaulay, Lower Ohau, Pukaki and Upper Ohau, as well as Lakes Ohau and
Pukaki (Maloney et al. 1997). The UWB population is sometimes referred
to in the literature as the Mackenzie Basin population (for example, in
Reed et al. 1993a). According to Dr. Richard Maloney of the Department
of Conservation, Twizel, New Zealand (in litt. November 2007), although
the two areas represent slightly different geographical boundaries, the
black stilt population being referred to is the same in either
instance. Because habitat quality in the species' present range is
considered to be higher than in other former localities, the species is
managed in situ (Maloney & Murray 2002).
The black stilt is considered locally extinct in 9 of the 13
Department of Conservation Conservancy Districts, occurring only in 2
districts (Canterbury and Otaga) on the South Island and 2 (Waikata and
Bay of Plenty) on the North Island (Hitchmough 2002). The majority of
the population remains in the UWB, on the South Island, year round (BLI
2007e; Maloney & Murray 2002: Pierce 1984a; Reed et al. 1993a; NZ CMaG
2007), and their breeding range is now entirely confined to the
wetlands and rivers of the UWB (Maloney & Murray 2002; Pierce 1984a).
Population Estimates
The wild black stilt population has undergone severe reductions in
numbers concomitant with the reduction in range area. In the 1950s, the
total population was estimated at 500 to 1,000 birds; however, within
one decade the population decreased to between 50 to 100 birds (Pierce
1996).
Since 1981, the New Zealand Department of Conservation has
intensively managed the wild black stilt population, including the
establishment of a captive population (Maloney & Murray 2002; Reed
1998; Reed et al. 1993a, 1993b). The captive breeding program entails
the transfer of ``eggs, chicks, juveniles and sub-adults from one part
of the range to any other part of the range'' (R. Maloney in litt.
October 2007). For further discussion on the captive breeding program,
see ``Management Plans,'' under Factor D.
Since the establishment of the captive breeding program, the
Department of Conservation has managed the global population of black
stilts, including captive-held and wild birds, as a single breeding
population (R. Maloney in litt. November 2007). Wild and reintroduced
birds are free to move across the full geographical range of the
species. Thus, the number of adults in the wild should be considered in
conjunction with the number of breeding pairs held in captivity.
According to Dr. Maloney (in litt. October 2007), a total wild
population number, including immature individuals, ``is not
informative'' because the total wild population is dependent on how
many young the breeding program produces and releases each year. The
number of breeding pairs is more informative as an indicator of the
status of the population (R. Maloney in litt. November 2007). The
number of available females is particularly important because of the
species' tendency to hybridize with pied stilt when male black stilts
are unable to find suitable mates (see Factor E) (Maloney & Murray
2002).
Wild population estimates: From 1975 to 1979, there were an
estimated 50 to 60 adults in the wild (Pierce 1984a); by 1981, only 23
adults remained in the wild (Maloney & Murray 2002; Van Heezik et al.
2005). In August 2000, there were 48 adults in the wild, of which 15 to
18 were females. As of February 2007, the wild adult population
consisted of 87 adults, including 17 productive pairs and a total of 41
females (DOC 2007b).
Captive-held population numbers: Throughout the 1980s, an average
of 15 birds was managed in captivity (Reed et al. 1993a). In 1998, the
number of managed birds reached 48 individuals. At that time, it was
decided that the captive-held population should be maintained at
approximately 6 breeding pairs. It was further determined that, in
order to maintain a genetic diversity among the breeding stock, a base
population of at least 18 breeding adults and juveniles would be
maintained as replacement stock and, barring a catastrophic loss of the
wild population, only first-generation captive stock would be used for
breeding (Reed 1998). As of 2007, the captive breeding program
consisted of 15 adults, including 6 productive pairs (DOC 2007b).
The black stilt is considered to be one of the rarest wading birds
in the world (BLI 2007e; Caruso 2006; Reed et al. 1993a). Since 1994,
the species has been categorized by the World Conservation Union (IUCN)
as ``Critically Endangered'' (BLI 2007a). The species' continued
existence in the wild today is considered a direct result of the
captive breeding program (Maloney & Murray 2002; Reed et al. 1993a; Van
Heezik et al. 2005). According to the priority management ranking
system devised by Molloy and Davis (1992) for the New Zealand
Department of Conservation, the species was ranked as a Category ``A''
species, which includes the ``highest priority threatened species''
(Hitchmough et al. 2005; Reed et al. 1993a). Under New Zealand
Department of Conservation's management system devised in 2002, the
black stilt is classified as ``Nationally Critical'' (Hitchmough et al.
2005). In the 2004 to 2005 breeding season, 7 pairs of captive-held
black stilt and 12 pairs in the wild produced ``up to 100 birds per
year for release into the wild'' (NZ CMaG 2007).
Summary of Factors Affecting the Black Stilt
A. The Present or Threatened Destruction, Modification, or Curtailment
of the Black Stilt's Habitat or Range
Today, it is estimated that only 10 percent of New Zealand's
wetlands remain intact (Caruso 2006). The
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braided river habitat of UWB is a globally rare ecosystem. With an
estimated area of 3,664 mi\2\ (9,490 km\2\), the UWB may account for 50
to 60 percent of the remaining suitable braided river habitat in New
Zealand (Caruso 2006; Maloney et al. 1997). The UWB is the only
breeding ground for the black stilt and most of the population remains
in the UWB year-round (Maloney & Murray 2002; Pierce 1984a; Reed et al.
1993a).
Several factors affect the quality of black stilt breeding and
nesting grounds. Among the most significant impacts to the UWB has been
the diversion of rivers for hydroelectric power (HEP) development
(Caruso 2006; Collar et al. 1994a; Maloney 1999). Since 1935, eight HEP
plants have been built on rivers, floodplains, and wetlands associated
with the UWB (Caruso 2006). The damming of rivers for HEP and flood
control projects has reduced river flows and interrupted the natural
flooding cycles vital to the creation and maintenance of the open
gravel braided river system of the UWB. It is estimated that
floodplains have been reduced by 17 percent in the 11 major rivers of
the UWB (Caruso 2006; Maloney & Murray 2002).
Disturbance by recreational users of riverbeds and riversides also
affects black stilt habitat within the UWB (Maloney & Murray 2002). The
riverine habitat where black stilts live and nest is a prime outdoor
recreation area. According to the New Zealand Ministry for the
environment (NZ MFE 2007), recreational activities include water sport
fishing, mountain biking, four-wheel driving, and jet skiing. Central
South Island Fish and Game New Zealand manages the Waitaki Catchment
(which includes rivers of the UWB and associated wetlands) and
considers the Catchment to be ``outstanding publicly accessible game
bird hunting and waterfowl habitat'' (NZ MFE 2007). According to the
New Zealand Ministry for the Environment (NZ MFE 2007), recreational
use and impacts on the areas of the Waitaki Catchment are predicted to
increase. The New Zealand Ministry for the Environment (2007) does not
address the effect that increased recreational activities will have on
the black stilt or other native species (See also Factor D). Maloney
and Murray (2002) indicate that the species does not tolerate human
disturbance. Recreational activities that are disruptive to the black
stilt's life cycle are considered to be a potentially serious threat to
the species (R. Maloney in litt. February 2007). Indiscriminate use of
off-road vehicles and jet-boats, disturbance by hikers and dogs, and
fishing and camping activities are disruptive to black stilts (Maloney
& Murray 2002). Recreational use of riverbed sites disturbs nesting
birds and prevents successful rearing of offspring (BLI 2007e).
Additional impacts on black stilt habitat include drainage for
fields or irrigation, overgrazing of wetlands, and water extraction for
agricultural irrigation (Caruso 2006; Collar et al. 1994a; Maloney &
Murray 2002). Since 1850, 40 percent of UWB wetlands have been drained
for farming (Caruso 2006). Proliferation of introduced weeds is a
problem (Maloney & Murray 2002). Invasive plants, especially the crack
willow (Salix fragilis), introduced by settlers as windbreaks, degrade
black stilt habitat by contributing to an overgrowth in formerly open
areas (Caruso 2006; Collar et al. 1994a; Maloney & Murray 2002: Pierce
1996; Reed et al. 1993).
Summary of Factor A
The black stilt's primary habitat and only known nesting ground
within the UWB is a globally rare ecosystem that is being altered by
water diversion, wetland conversion, invasive species, and recreation.
Lack of suitable habitat for feeding and nesting increases the species'
risk of extinction. The species does not tolerate human disturbance,
and recreational activities within the species' riverside nesting
grounds has the potential to disrupt the species' breeding success.
Reduction in habitat quality is likely to increase the vulnerability of
black stilt to predation (see Factor C). We find that the black stilt
population is at significant risk throughout all of its range by the
present or threatened destruction, modification, or curtailment of its
habitat.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes et al.here is no known threat to the species from
use for commercial, recreational, scientific, or educational purposes.
The species has not been formally considered for listing in the
Appendices of CITES (http://www.cites.org).
C. Disease or Predation
There are currently no known diseases affecting the black stilt in
the wild. Jakob-Hoff (2001) of the Auckland Zoo Wildlife Health and
Research Centre, New Zealand, conducted a risk assessment for disease
transmission caused by the translocation of captive black stilt to the
wild population. The assessment considered a number of ``diseases of
concern'' that may potentially threaten the wild population, including
salmonellosis, yersiniosis, campylobacteriosis, pasteurellosis (fowl
cholera), capillariasis, cestodiasis, trematodiasis, avian malaria, and
coccidiosis. The assessment found no reported major die-offs of wild
black stilts resulting from infectious diseases carried by birds
translocated from captivity to the wild. Most of the illnesses and
deaths that occurred among captive-reared birds were related to
husbandry and could be controlled with improved husbandry methods, such
as improved diet and parasite screening. Finally, the assessment
suggested the establishment of a surveillance program to determine the
prevalence of significant disease outbreaks in wild black stilts and
facilitate development of pre-release quarantine and health-screening
protocols regarding captive-reared birds (Jakob-Hoff 2001). A screening
program for potential pathogens and improved husbandry methods specific
to the black stilt captive population were outlined in the 1998
management plan for captive black stilts (Reed 1998). In 2005, a review
of the records since 1995 for captive-held birds showed that infection,
along with trauma, was a major cause of death among all age classes in
captivity, especially chicks within the first two weeks after hatching
(Van Heezik et al. 2005). Van Heezik et al. (2005) reported that
protocols that monitor birds, intervene at the first signs of illness,
and minimize the introduction of pathogens into the breeding unit were
strictly adhered to. This has prevented the spread of these infectious
diseases among captive-held birds or transmission into the wild
populations (Van Heezik et al. 2005).
Predation by introduced mammalian predators and by unnaturally high
numbers of avian predators is a primary threat to the black stilt (R.
Maloney in litt. February 2007). Non-native predators introduced since
the late 19th century include feral cats (Felis catus), ferrets
(Mustela furo), stoats (M. erminea), hedgehogs (Erinaceus europaeus),
and brown rats (Rattus norvegicus) (Maloney & Murray 2002; R. Maloney
in litt. February 2007; Pierce 1996; Sanders & Maloney 2002). In
addition, population numbers of avian predators, such as the non-native
Australian harrier (Circus approximans) and the native kelp gull (Larus
dominicanus), are unnaturally high because of human-induced changes,
such as the introduction of rabbits, agricultural development, and the
presence of rubbish dumps (Dowding & Murphy 2001; Maloney & Murray
2002). New Zealand is home to only one native
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mammal, a species of bat, and introduced mammalian predators pose a
great risk to native bird species of New Zealand, including the black
stilt, because these species evolved in the absence of these predators
(Caruso 2006).
Several aspects of the black stilt's life history and nesting
behavior contribute to heavy predation losses (Dowding & Murphy 2001).
Solitary ground-nesting birds, the black stilt's preference for open
nesting sites and feeding areas, such as dry, stable riverbanks, may
increase their susceptibility to predation by mammalian predators, such
as feral cats and ferrets, which use the banks as pathways (Maloney &
Murray 2002; Pierce 1982; Pierce 1986b; Reed et al. 1993a). Nesting as
early as August, when other prey sources are less available, adds to
the black stilts' vulnerability (Reed et al. 1993a). Both sexes share
nesting responsibility during the lengthy fledging period and are
equally vulnerable to predation during the breeding season (Maloney &
Murray 2002; Pierce 1986b; Pierce 1996; Sanders & Maloney 2002). Black
stilts exhibit ineffective anti-predator behavior, contributing to
significant mortality of nestlings and fledglings (Maloney & Murray
2002). For instance, black stilts do not perform distraction displays
until late in incubation (Reed et al. 1993a). They will also re-nest in
the same site if a clutch is lost to predation (Pierce 1986b; Sanders &
Maloney 2002).
To test the effects of predation on the black stilt, Pierce (1986a)
undertook a predator control study in a portion of the species' range
during three breeding seasons, from 1977 to 1979, monitoring a total of
50 nests. Traps were placed around 23 randomly selected nests; these
nests were ``protected.'' These and the remaining 27 nests, designated
as ``unprotected,'' were monitored. Pierce (1986a) determined that 64
percent of black stilt breeding failures were attributed to predation
and found that success in fledging and breeding increased at protected
nests to 32.5 percent and 10.8 percent, respectively (R. Maloney in
litt. February 2007). Most predation was caused by brown rats (14
nests), ferrets (13 nests), and cats (11 nests).
In a review of 499 eggs placed in the wild from 1979 to 1999,
mortality was attributed to predation (45 percent); unknown causes (43
percent); flooding (10 percent); and human disturbance, disease, cold
weather, poor parenting, and starvation (2 percent) (Maloney and Murray
2002). However, direct observation of predation events is difficult (R.
Maloney in litt. February 2007), and, of all these deaths, only 11 were
known conclusively (5 of which were directly observed predation
events).
In an unpublished report by Saunders et al. (1996, as cited in
Dowding & Murphy 2001), predation may have accounted for nearly 77
percent of black stilt chick losses between 1982 and 1995. Using video
cameras, Sanders and Maloney (2002) studied the causes of mortality on
ground-nesting birds in the UWB. The study monitored 23 black stilt
nests and recorded 5 lethal events attributed primarily to cats and
harriers. Cats were observed eating eggs, killing an adult nesting
bird, and stalking nests. One black stilt nest containing ceramic eggs
was visited by cats nine times over a 32-day period. A harrier ate a
chick and a hatching egg in another nest. Unlike other bird species
being observed in the same study, black stilts continued to nest upon
dummy eggs even after being visited by cats, revealing that the use of
dummy eggs increased their risk of mortality and further confirming
that the species is ill-adapted to this predation pressure (Sanders &
Maloney 2002).
Despite 20 years of predator trapping undertaken by the New Zealand
Department of Conservation to protect black stilt nesting and fledging
attempts, predator control efforts have met with mixed success.
Fledging success (the number of chicks fledged versus the number of
chicks hatched) was increased in some but not all years (Keedwell et
al. 2002). In a review of predator trapping activities conducted
between 1981 and 2000, Keedwell et al. (2002) found that efforts were
inconsistent, resulting in highly variable results each season. For
instance, predator control was sometimes undertaken for the entire
breeding season but other times began well after the start of the
breeding season. Keedwell et al. (2002) calculated that over the 20-
year management period, the effort expended in predator control was
equivalent to roughly 9.8 ``person years.'' According to Dr. Maloney
(in litt. March 2007), the intensity and scale of control need to be
significantly expanded to be effective in increasing fledgling survival
and recruitment.
Summary of Factor C
For the reasons outlined above, we believe that disease is not
currently a contributory threat factor for the black stilt. Predation
by introduced mammalian and avian predators causes black stilt
mortality at all life stages. Despite evidence that predator control
significantly increased the species' breeding success, predator control
efforts have been limited and inconsistent. We consider predation to be
a significant contributory factor currently threatening this species
and one that is projected to continue in the future.
D. The Inadequacy of Existing Regulatory Mechanisms
Four aspects are considered under this factor: National protection,
habitat protection, the black stilt's status as a culturally
significant species, and the species' management plans.
National protection: The black stilt is an ``absolutely protected''
species under the New Zealand's Wildlife Act of 1953 (1953 Act No. 31
1953). Under this Act, it is illegal to (a) hunt or kill; (b) buy,
sell, or otherwise dispose of, or have possession of any absolutely
protected wildlife or any skin, feathers, or other portion, or any egg
of any absolutely protected wildlife; or (c) rob, disturb, or destroy,
or have possession of the nest of any absolutely protected species
(Part 5, 63(1)). Violations of this law by individuals can result in
imprisonment for a term not exceeding 6 months; or a fine not exceeding
$100,000 plus a further fine not exceeding $5,000 for each head of
wildlife and egg of wildlife in respect of which the offence is
committed (Part 5, 67(A)(1)(a)). Violations by corporations can result
in a fine not exceeding $200,000 plus a further fine not exceeding
$10,000 for each head of wildlife and egg of wildlife in respect of
which the offence is committed (Part 5, 67(A)(1)(a)). Given that take
by humans is not a threat to the black stilt, this law does not reduce
any threats to the species.
Habitat protection: New Zealand protects more than 30 percent of
its total land area as reserve land (Craig et al. 2000; Green &
Clarkson 2006). However, except for a few small and scattered wetland
reserves, most black stilt habitat is unprotected by the government
(Maloney & Murray 2002). Habitat modification, including diversion or
use of water for electrical generation, agriculture, and recreational
activities (as discussed under Factor A), is a primary threat to this
species.
The Waitaki Catchment Water Allocation Plan addresses water
allocation for activities that involve the take, use, damming, and
diversion of water in relation to the Waitaki Catchment. The most
recent plan was approved in 2004 by the New Zealand Ministry for the
Environment, in accordance with the Resource Management Act of 1991 and
the Resource Management (Waitaki Catchment) Amendment Act of 2004 (NZ
MFE 2005). The objectives of the
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Waitaki Catchment Regional Plan were to balance electrical generation
with conservation and other human uses of the Catchment, including an
evaluation of minimum lake levels required to achieve these objectives.
The evaluation gave specific consideration to the effect of water flow
changes on the feeding, roosting, and breeding habitat of the black
stilt (and other wetland birds), and it was determined that the
established water levels were suitable for these wetland species (NZ
MFE 2005). However, the Waitaki Catchment Regional Plan provided
exemptions for other activities that also adversely affect black stilt
and its habitat, including certain agricultural uses and recreational
activities (See Factor A). Policy 35 of the Waitaki Catchment Water
Allocation Plan exempts certain activities from allocation limits,
including ``tourism and recreational facilities from the lakes [Tekapo,
Pukaki and Ohau] and from the canals leading from them'' (NZ MFE 2004).
Rule 2(2) of the Waitaki Catchment Water Allocation Plan exempts
``stock drinking-water * * * and processing and storage of perishable
produce'' from consideration under the allocation limits (NZ MFE 2005).
Thus, while the Waitaki Catchment Water Allocation Plan addresses
regulation on water levels associated with hydroelectric power
generation, it did not address or reduce threats to black stilt habitat
from water diversion for certain agricultural and recreational
activities, which is adversely affecting the black stilt (Factor A).
Status as a culturally significant species: The UWB is considered a
``taonga,'' and the black stilt a ``taonga'' species for the Ngai tahu,
the native tribal population inhabiting most of the South Island, New
Zealand (Schedule 97 1998; NZ MFE 2005). ``Taonga'' is a Maori word for
any item, object or thing that has special significance to the culture,
including birds and plants (Auckland Museum 1997). Under the Ngai
tah[umacr] Claims Settlement Act of 1998, the New Zealand Department of
Conservation must consult with, and have particular regard to, the
views of the Ngai tah[umacr] when making management decisions
concerning ``taonga'' species (1998 Act No. 97. 1998; Maloney & Murray
2002). An Ngai tah[umacr] representative is a member of the Kak[iuml]
Recovery Group (Maloney in litt. February 2007), which implements the
management plan for the black stilt (Maloney & Murray 2002). Including
the tribes in resource decision-making is an important conservation
strategy undertaken by the New Zealand government (NZ MFE 2001). New
Zealand's Resource Management Act of 1991 is based on sustainably
managing resources, while encouraging community and individual
involvement in the planning for conservation (NZ MFE 1991). We believe
that local involvement is important for resource conservation and may
help to reduce threats to the species by increasing awareness of the
conservation risks.
Management plans: According to the New Zealand Ministry of
Environment, high priority is afforded to the black stilt recovery plan
(NZ MFE 1997). Beginning in 1981, the New Zealand Department of
Conservation undertook management of the wild black stilt population to
increase fledging success and recruitment of juveniles in the declining
populations in Mackenzie basin (R. Maloney in litt. March 2007; Reed et
al. 1993b). Since 1993, black stilt management has been guided by two
consecutive recovery plans, the first published in 1993 (Reed et al.
1993a) and a second, updated plan approved in 2002 (Maloney & Murray
2002), that covers the period 2001-2011.
The goals of the current recovery plan (effective from 2001 to
2011) are to increase the black stilt population within the next 10
years to more than 250 breeding individuals, with a mean annual
recruitment rate that exceeds the mean annual adult mortality rate
(Maloney & Murray 2002). There are two overlapping phases. Phase 1 of
the program involves a series of objectives aimed at increasing the
number of black stilts in the wild by maximizing recruitment rate both
in the wild (for instance, by ensuring that all female black stilts are
mated with a male each season) and by captive-rearing black stilts and
releasing large numbers of captive-born young to the wild. A review of
captive breeding records from two breeding seasons (1981 to 1982 and
2001 to 2002) found that the survival rate of captive-bred stilts that
were reintroduced to the wild was 88 percent at 2 months and 82 percent
at 10 months (Van Heezik et al. 2005). Between 1992 and 1999,
researchers determined that the recruitment rate of chicks that had
been artificially incubated in captivity and then hatched and raised in
the wild was only 4 percent, with only 8 of the 189 chicks surviving to
2 years of age. However, birds that were hatched and raised in
captivity and then released into the wild achieved a minimum
recruitment rate of 22 percent (Maloney & Murray 2002). Thus, wild
losses of eggs, chicks, and fledglings are largely avoided by
artificially incubating and captive-rearing young to 3 or 9 months of
age before releasing them back to the wild. This technique has been
used for most eggs since 1998, and has resulted in approximately 30
percent recruitment rate (Van Heezik et al. 2005).
A second concurrent phase seeks to increase black stilt breeding
success and adult survival in the wild by continuing research on the
primary causes of mortality and developing mitigation measures to
prevent excess mortality. Attempts to monitor all forms of mortality
via direct observation began in 1998 and are ongoing. Goals under this
phase include obtaining a better understanding of the causes of chick
and adult mortality, developing multi-species predator control methods,
and understanding mate choice decisions at different population
densities. As an example, because monitoring birds between post-flight
to adulthood is difficult, researchers are monitoring adults using
transmitters (Maloney & Murray 2002). In September 2007, researchers
released 38 adult black stilts fitted with transmitters (Timaru Herald
2007). These transmitters help researchers locate wild birds that have
died (Maloney & Murray 2002).
The management of the captive black stilt population is addressed
in both recovery plans (Reed et al. 1993; Maloney & Murray 2002), and
also in a separate Department of Conservation management plan published
in 1998 (Reed 1998). According to Reed (1998), the goals of the captive
management plan are to provide young birds for release into the wild
and develop a self-sustaining captive population. Five objectives were
established to achieve these goals: (1) Establish a captive population
capable of being self-sustaining, (2) provide juveniles for release and
eggs for fostering to the wild, (3) undertake research to increase
productivity and survival, (4) establish health monitoring of the
captive population, and (5) advocate conservation of black stilts to
the general public. This management plan outlines the expansion of the
captive breeding program and formalizes the protocols for captive
release, health screening, and monitoring.
Experts consider that, despite only incremental success in
increasing wild population numbers, the captive-breeding program, along
with predator control, have prevented the species from going extinct in
the wild (BLI 2007e; Maloney & Murray 2002: Reed et al. 1993; Van
Heezik et al. 2005). The management plans are addressing several
aspects to facilitate the species' recovery, including research into
survival, production of offspring for release into the wild, and
continued
[[Page 3153]]
research into the causes of mortality in the wild, including predation.
However, the relative success of the captive breeding program is
hindered by the inadequacy of regulatory mechanisms, combined with
limited or inconsistent efforts to control predators (Factor C) and
conserve and provide suitable habitat for the species (Factor A).
Summary of Factor D
Regulatory mechanisms exist to protect the black stilt from take.
However, take is not a primary threat to the species. Government-
sponsored measures are in place to facilitate the species' recovery (as
discussed under this factor), including mitigating threats from
predation (as discussed under Factor C). However, the inadequacy of
regulatory mechanisms to protect or curb habitat destruction in the
species' only known breeding ground (Factor A), combined with
inconsistent predator control (Factor C), results in failure to reduce
or remove threats from the species' habitat. As such, we believe that
the inadequacy of regulatory mechanisms is a contributory risk factor
currently and in the future for this species.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
Three additional factors are considered herein: Genetic risks
associated with small population sizes, hybridization, and threats from
stochastic events (random natural occurrences).
Genetic risks associated with small population sizes: The small
size of the black stilt population, estimated in 2007 as 87 adults
consisting of 17 breeding pairs (DOC 2007b), makes this species
vulnerable to any of several risks, including inbreeding depression,
loss of genetic variation, and accumulation of new mutations.
Inbreeding can have individual or population-level consequences either
by increasing the phenotypic expression (the outward appearance or
observable structure, function or behavior of a living organism) of
recessive, deleterious alleles or by reducing the overall fitness of
individuals in the population (Charlesworth & Charlesworth 1987;
Shaffer 1981). Small, isolated populations of wildlife species are also
susceptible to demographic problems (Shaffer 1981), which may include
reduced reproductive success of individuals and chance disequilibrium
of sex ratios. Research has shown that the long-term survival of the
black stilt as a species requires gene flow to be at least 5 percent,
and that the present gene flow is approximately 15 percent (Maloney &
Murray 2002). However, the relatedness of the entire black stilt
population has not been determined, and inbreeding depression is a
possible threat (Maloney & Murray 2002).
A general approximation of minimum viable population size is the 50
/ 500 rule (Soul[eacute] 1980; Hunter 1996). This rule states that an
effective population (Ne) of 50 individuals is the minimum
size required to avoid imminent risks from inbreeding. Ne
represents the number of animals in a population that actually
contribute to reproduction, and is often much smaller than the census,
or total number of individuals in the population (N). Furthermore, the
rule states that the long-term fitness of a population requires an
Ne of at least 500 individuals, so that it will not lose its
genetic diversity over time and will maintain an enhanced capacity to
adapt to changing conditions.
The available information for 2007 indicates that the breeding
population of the black stilt (based on the number of wild and captive-
held breeding pairs) is 46 individuals (DOC 2007b); 46 is just below
the minimum effective population size required to avoid risks from
inbreeding (Ne = 50 individuals). Moreover, the upper limit
of the population is 102 adults (DOC 2007b). This represents the
maximum potential number of reproducing members in the wild black stilt
population and is less than one-fifth of the upper threshold
(Ne = 500 individuals) required for long-term fitness of a
population that will not lose its genetic diversity over time and will
maintain an enhanced capacity to adapt to changing conditions. As such,
we currently consider the species to be at risk due to lack of near-
and long-term viability.
Hybridization: Black stilt males and pied stilt females can produce
fertile offspring (BLI 2007e; DOC 2007a; Maloney & Murray 2002; Reed et
al. 1993a). However, hybrid offspring exhibit distinct differences in
survival rate and behavior that may be deleterious to the species'
long-term survival (Reed et al. 1993a). Hybrid survival to adulthood is
about 50 percent that of the offspring of pure black stilt pairs. In
addition, researchers noted changes in behavioral patterns in chicks
fostered to pied stilt parents between 1981 and 1987. Due to the
limited number of wild black stilt breeding pairs, part of the species'
management plan at that time was to cross-foster black stilt eggs to
pied stilt parents. Cross-fostered black stilts were half as likely to
be re-sighted in the UWB and mixed pairs were more likely to
participate in migratory behavior with the pied stilt population rather
than remain in their natal range, as pure black stilts would. As a
result, cross-fostering of black stilt eggs with pied stilt parents was
discontinued. More importantly, this research revealed that
hybridization was detrimental to the long-term survival of the black
stilt, as mixed pairs were effectively ``lost'' from the population
(Reed et al. 1993b).
Hybrid management (such as breaking up mixed-pair bonds prior to
mating) is part of the conservation strategy identified in the black
stilt recovery plan, and researchers believe black stilts possess
several inherent qualities that reduce gene flow, such as the black
stilt's strong positive assortative mating (selecting black stilt over
pied stilt when given the choice) and the low fitness of hybrid
offspring (Maloney & Murray 2002). However, black stilts live in
relative isolation from each other, and nesting pairs are often located
miles (kilometers) apart (BLI 2007e; DOC 2007a; Pierce 1984a; Reed et
al. 1993a). Sex ratios are an important indicator of the species'
tendency to pair with pied stilts (Maloney & Murray 2002), and experts
note that black stilts pair with the pied stilt when ``suitable'' mates
within the species are not available (DOC 2007a; Greene 1999; NZ CMaG
2007; Reed et al. 1993a). Given the species' dispersed nature, the
likelihood for hybridization with the growing population of pied stilts
increases as black stilt population numbers decrease and black stilt
males are less able to find females (Greene 1999; Pierce 1996).
Threats from stochastic events: With a wild adult population of 87
adults (DOC 2007b), experts consider the risk of a single catastrophic
event to be a serious threat that could destroy most of the population
(Maloney & Murray 2002). New Zealand's South Island is subject to
tsunamis and earthquakes. According to the New Zealand Institute of
Geological and Nuclear Sciences (NZ GNS) (2007), since 1840, when
tsunami recordkeeping began, 10 tsunamis measuring 16.4 ft (5 m) or
higher have hit New Zealand. New Zealand is vulnerable to tsunamis
because of the high amount of seismic activity in the region.
Approximately 10,000 to 15,000 earthquakes occur in New Zealand
annually, most of low magnitude (Quake Trackers 2007). New Zealand is
expected to experience earthquakes of magnitude of 7 on the Richter
scale only about once a decade (Walsh 2003). However, since 2003, the
southern region of the South Island has been rocked by at least three
earthquakes near or above that magnitude. Centered in or near
Fiordland, 266 mi (429 km) south of the heart of black stilt territory
(The
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New Zealand (NZ) Herald 2004, 2007; Walsh 2003), the years and
magnitudes of each of these high-magnitude earthquakes were: 2003, 7.2
magnitude; 2004: 7.2 magnitude; 2007: 6.7 magnitude (NZ Herald 2004,
2007; Walsh 2003). The 2003 earthquake was the first on-land earthquake
of this magnitude since 1968 (Walsh 2003). The main quake triggered a
small tsunami that brought flooding as far north as Haast (Jackson
Bay), less than 100 mi (161 km) from the UWB, where the majority of the
black stilt population lives year-round and the only known breeding
ground for the species (McGinty & Hancox 2004; Walsh 2003). At least
5,000 aftershocks were recorded from the 2003 earthquake, one
registering 6.1 on the Richter scale (McGinty & Hancox 2004; NZ Herald
2007). More than 400 landslides were triggered, the largest of which
sent 262,000 cubic yards (yd\3\) (200,000 cubic meters (m\3\)) of soil
crashing down the fiord at Charles Sound, triggering a 3 to 6 ft (1 to
2 m) high tsunami that inundated surrounding vegetation 13 to 16 ft (4
to 5 m) above sea level (McGinty & Hancox 2004). According to Maloney
and Murray (2002), flooding was the second leading cause of egg
mortality in a study conducted between 1977 and 1979. Stochastic
events, such as earthquakes and tsunamis, could result in extensive
mortalities from which the population may be unable to recover, leading
to extinction (Caughley 1994; Charlesworth & Charlesworth 1987; Maloney
& Murray 2002).
Summary of Factor E
The black stilt is subject to genetic dilution, including changes
in survival and behavior, due to demographic problems and hybridization
with the pied stilt, and is also susceptible to other genetic risks,
such as inbreeding, due to its small population size. The species is
vulnerable due to stochastic event, such as a tsunamis or earthquakes,
which are known to occur in the region. We consider the species'
extremely small population size, along with the associated risks of
genetic dilution, demographic shifts, and vulnerability to stochastic
events, to be significant risks factors throughout the black stilt's
range currently and in the future.
Conclusion and Determination for the Black Stilt
We have carefully assessed the best available scientific and
commercial information regarding the past, present, and potential
future threats faced by the black stilt. We have determined that the
species is in danger of extinction throughout all of its known range
primarily due to ongoing threats to its habitat (Factor A); predation
(Factor C); and genetic dilution from hybridization, lack of near- and
long-term genetic viability, and susceptibility to stochastic events
due to risks associated small population sizes (Factor E). Furthermore,
we have determined that the inadequacy of existing regulatory
mechanisms is a contributory risk factor that endangers the species'
continued existence (Factor D). Therefore, we are determining
endangered status for the black stilt under the Act. Because we find
that the black stilt is endangered throughout all of its range, there
is no reason to consider its status in any significant portion of its
range.
II. Caerulean Paradise-Flycatcher (Eutrichomyias Rowleyi)
Species Description
The caerulean paradise-flycatcher is a member of the Monarchidiae
family, locally known as ``burung niu'' (Whitten 2006). It is native to
Indonesia, and adults are about 5 in (18 cm) in height, with a long
tail and long rictal bristles (stiff hairs around the base of the bill)
(Riley & Wardill 2001; Whitten et al. 1987). There is scant biometric
data for this species, because, other than the type specimen, only one
additional specimen was captured, measured, and released in 1998 (Riley
& Wardill 2001). The species is described as a bright cerulean blue
(which can be likened to a deep blue sky) with gray undertones on the
belly, legs, upper wing coverts (feathers) and down the sides of the
neck to the breast (BLI 2007d; Riley & Wardill 2001; Whitten et al.
1987). The type specimen, which was described as a male, is slightly
larger and duskier in appearance than the specimen measured in 1998,
leading researchers to believe that the former specimen was a juvenile
and the latter, a female (Riley & Wardill 2001).
Taxonomy
The first specimen of caerulean paradise-flycatcher was collected
by Meyer in 1873. The species has always been placed in the
Monarchidiae family, but within three different genera. When described
in 1878, Meyer placed the species in the genus Zeocephus; later it was
placed in the genus Hypothymis (Riley & Wardill 2001; Whitten et al.
1987). In 1939, it was placed into the monotypic genus Eutrichomyias,
also of the Monarchidae family, and distinguished from Hypothymis by
its abundant rictal bristles (Riley & Wardill 2001). Riley and Wardill
(2001) suggest that the species may be more related to Hypothermis, but
insufficient information impedes a conclusive decision. Therefore, we
accept the species as Eutrichomyias rowleyi, which follows the
Integrated Taxonomic Information System (ITIS 2007).
Habitat and Life History
The caerulean paradise-flycatcher was known only from its type
specimen until 1998. Current knowledge of its ecology and behavior are
based on 33 sightings between 1998 and 1999 (Riley & Wardill 2001;
Whitten et al. 1987). Riley and Wardill (2001) point out that the basic
lack of ecological information on this species impedes its
conservation. Information about the species' range, behavior,
reproduction, and population size is quite limited.
The species has been observed mostly in the steep-sloped, closed
canopies of low-elevation broadleaf primary forest, between 1,394 and
2,133 ft (425 and 650 m). A few birds were observed foraging on a scrub
forest ridge top or in secondary forest, but only when those areas were
bordered by primary forest. The caerulean paradise-flycatcher prefers
primary forest habitat, but can forage in secondary scrub that is
bordered by primary forest; however, the species is absent from
disturbed habitat away from primary forest (http://www.rdb.or.id; BLI 2001a,
2007d; Riley & Wardill 2001).
The species is often observed foraging in association with other
bird species and a particular squirrel species, believed to be the
Celebes dwarf squirrel (Prosciurillus murinius) (Riley & Wardill 2001).
Adept at catching flies in the air, this insectivore feeds primarily in
the canopy and sub-canopy, but is known to descend to the understory
(http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001).
Experts believe that the species is sedentary, as individuals do
not appear to move between the valleys in which they are observed
(http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001). The largest
recorded flock size has been five birds (Riley & Wardill 2001). Based
on two sightings of young, in October and in December, researchers
presume that nesting and fledging occur in that time period
(http://www.rdb.or.id; BLI 2001a; Riley & Wardill 2001). Researchers believe
the bird builds nests of palm leaves (likely Arenga spp.) in the
branches of understory trees (including Szygium spp.) from 7 to 8 ft (2
to 2.5 m) off the ground (http://www.rdb.or.id; BLI 2001a; Riley & Wardill
2001). Both sexes appear to care for the young (Riley & Wardill 2001).
[[Page 3155]]
Historical Range and Distribution
The only known range of the caerulean paradise-flycatcher is on
Sangihe Island, north of Sulawesi, Indonesia (Riley & Wardill 2001;
Whitten et al. 1987). Sangihe Island, also known as Great Sangihe,
Great Sangir, or Sangir Besar Island, is part of the Sangihe-Talaud
archipelago (Whitten et al. 1987) in the waters between Sulawesi
(northern Indonesia) and the Philippines (Brodjonegoro et al. 2004).
The archipelago consists of two island groups, the Sangihe group and
the Talaud group, and until 2002, the entire island group was
administered as one unit. Thus, most available information on the
archipelago concerns both island groups.
The Sangihe-Talaud archipelago includes 77 islands; 56 are
inhabited, including Sangihe (Brodjonegoro et al. 2004). The total land
mass of the Sangihe-Talaud archipelago is 314 mi\2\ (813 km\2\) (Mous &
DeVantier 2001), of which Sangihe Island includes 270 mi\2\ (700 km\2\)
(Riley 2002), making it the largest island in the archipelago. The
Island became part of the Dutch East India Company in the 17th century,
and remained primarily under Dutch control for the next 300 years
(Simkin and Siebert 1994). In some of the earliest accounts, Sangihe
Island was already known for its coconut and nutmeg plantations (New
York Times Archives 1892). Most of Sangihe Island was deforested by
1920, having been logged for timber and paper production or converted
to cash crop plantations (Riley 2002; Riley & Wardill 2001; Whitten et
al. 1987).
The extent of the caerulean paradise-flycatcher's historic
distribution is not well known because there have been so few sightings
of this species. Following the initial discovery of the species in
1873, there were only two reported sightings; both unconfirmed (Riley &
Wardill 2001). By the 1980s, with no confirmed sightings of live
caerulean paradise-flycatchers for over 100 years, the species was
presumed extinct due to loss of habitat (Riley & Wardill 2001; Thompson
1996; Whitten et al. 1987).
Current Range and Distribution
The caerulean paradise-flycatcher was rediscovered in 1998 (Riley &
Wardill 2001), occupying the forested valleys around the base of Mount
Sahendaruman, on the southern part of Sangihe Island (http://www.rdb.or.id;
BLI 2001a; BLI 2005; Riley & Wardill 2001). An extinct volcano, Mt.
Sahendaruman is variously referred to as: Gunungan Sahendaruman and
Gunungan Sahengbalira (the latter of which is actually the name of a
mountain peak) (http://www.rdb.or.id; BLI 2001a) and Pegunungan
Sahendaruman (BLI 2004b). Mt. Sahendaruman supports the only extensive
remaining primary forest on the island (http://www.rdb.or.id; BLI
2001a, 2007d; Riley & Wardill 2001) and is home to three critically-
threatened species of birds, including the caerulean paradise-
flycatcher; no other area in Indonesia supports more than one
critically threatened bird species (BLI 2001a).
Mt. Sahendaruman extends to an altitude of approximately 3,382 ft
(1,031 m) (Riley 2002). The entire forest covers an area of less than 3
mi\2\ (8 km\2\). However, because of the species' preference for
riverine habitat at elevations from 1,394 to 2,133 ft (425 to 650 m),
the actual range available to the flycatcher is estimated to be an area
of 0.8 mi\2\ (2 km\2\) on the lower valleys near the fringe of the
forest (http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001).
Moreover, because the species is rarely seen at higher elevations,
experts believe that this species has reached its upper elevational
limit (Riley & Wardill 2001).
Population Estimates
The population is estimated to be between 19 and 135 individuals.
This estimate is based on inferences made from 33 sightings between
1998 and 1999 (http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001).
The basis for this estimate is well explained by Riley and Wardill
(2001, p. 49), who note the possibility that the total population may
consist of only those 19 observed birds. More recent census data is not
available.
Conservation Status
The caerulean paradise-flycatcher is a protected species in
Indonesia (J.C. Wardill in litt. 1999, as cited in BLI 2001a). The IUCN
considers this species to be ``Critically Endangered'' due to its low
estimated population size and restricted range (BLI 2004a).
Summary of Factors Affecting the Caerulean Paradise-Flycatcher
A. The Present or Threatened Destruction, Modification, or Curtailment
of the Caerulean Paradise-flycatcher's Habitat or Range
Today, much of Sangihe Island is covered by plantations or
secondary forests and the caerulean paradise-flycatcher's habitat on
Mt. Sahendaruman provides the only remaining extensive primary forest
on the island (Riley & Wardill 2001; Whitten et al. 1987). Land use
patterns on Sangihe Island have been fairly stable (Vidaeus 2001), and
there have been no significant forest losses on Sangihe Island (Whitten
2006) because the Sangihe Island economy is not driven by timber
harvest as in other parts of Indonesia. The inaccessibility of Mt.
Sahendaruman forest made timber extraction uneconomical (Vidaeus 2001).
However, Riley & Wardill (2001) noted that the caerulean paradise-
flycatcher likely only existed on Mt. Sahendaruman because of the
steep, fairly inaccessible terrain.
Most threats to the caerulean paradise-flycatcher habitat have been
locally derived (Vidaeus 2001), caused by smaller scale activities on
the lower fringes of the primary forest on Mt. Sahendaruman (Riley &
Wardill 2001), including within the boundaries of the Mt. Sahendaruman
Protection Forest (see Factor D). Forest clearing by farmers is
generally small scale, between 53,820 to 161,459 square ft (ft\2\)
(5,000 to 15,000 m\2\), and occurs along the fringes of the primary
forest, which is adjacent to the species' preferred habitat. BirdLife
International (2006c) reported that shifting cultivation has caused the
gradual erosion of the lower fringes of the primary forest on Mt.
Sahendaruman. Encroachment for forest product extraction on the fringes
of the forest also disrupts the flycatcher's habitat (http://www.rdb.or.id;
BLI 2001a, 2007d Kirby 2003a; Riley & Wardill 2001). Forest is also
cleared for wood, paper production, conversion to cash crops, shifting
cultivation, and settlements (Riley & Wardill 2001; Whitten et al.
1987). Researchers believe that the species has reached its upper
elevational limit and that human pressures on the lower fringes of its
habitat have boxed the species into its current range (http://www.rdb.or.id;
BLI 2001a; Riley & Wardill 2001).
Summary of Factor A
The caerulean paradise-flycatcher is currently limited to an area
of suitable habitat that may be as small as 0.8 m2 (2
km2) on Mt. Sahendaruman. Preferring lower elevations, the
species appears to have reached its upper elevational limit for
suitable habitat. Encroachment on the fringes at the base of the
mountain threatens the species to the lower extent of its range. Given
the caerulean paradise-flycatcher's limited range and preference for
closed-canopy primary forest, habitat modification even at a small
scale can have a profound effect on the species. Based on the above
information, we believe that the present and future threatened
destruction, modification, or curtailment of the caerulean paradise-
flycatcher's habitat or range threatens the species throughout its
range.
[[Page 3156]]
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
While there is no documented evidence that the species is a
specific target of hunting, researchers familiar with the area and the
species consider indiscriminate hunting to be a risk factor for this
species (Riley & Wardill 2001; http://www.rdb.or.id; BLI 2001a). Sangihe
Island locals are known for hunting birds indiscriminately with air
rifles as a hobby in and around the forests of Mt. Sahendaruman (BLI
2001a; Riley & Wardill 2001). BirdLife International (2006c) describes
hunting pressures on small passerines, to which group of birds the
caerulean paradise-flycatcher belongs, as ``intensive.'' Riley and
Wardill (2001) noted that while conducting fieldwork in Mt.
Sahendaruman forest in 1998, a group of three hunters were observed
carrying 20 to 30 birds of all sizes that had been shot.
Indiscriminate hunting has resulted in declines of more accessible
bird species on the island (http://www.rdb.or.id; BLI 2001a) and locals have
identified hunting as a key cause for the decline in bird species in
the Mt. Sahendaruman area (BLI 2001a). The practice is so pervasive
that BirdLife International--Indonesia Programme (Vidaeus 2001) has
focused on creating educational materials aimed at school children to
encourage them to find alternative hobbies to hunting. Given the
species' extremely small population size, between 19 and 135
individuals, indiscriminate hunting of even a few individuals would
have a detrimental effect on the population (See Factor E).
Riley (2002) conducted research on mammal hunting on Sangihe
Island, finding that, after habitat loss, hunting pressure was the
biggest threat on the island. In interviews with local farmers, 77
percent of the farmers admitted to hunting mammals variously using air
rifles, snares and mist nets. Furthermore, hunting pressure was
particularly high for the bear cuscus (Ailurops ursinus melanotis), a
small marsupial found only in the primary forests of Mt. Sahendaruman,
the same habitat as the caerulean paradise-flycatcher. Riley and
Wardill (2001) characterize the flycatcher as adverse to human
disturbance, and hunting pressures in the same habitat as the
flycatcher contribute to disturbance activities that are disruptive to
the species (as described under Factor A).
The species is not known to be in international trade and has not
been formally considered for listing under CITES (http://www.cites.org).
Summary of Factor B
Indiscriminate bird hunting and hunting-related disturbances are
widespread within the species' range (Mt. Sahendaruman forest). The
species has an extremely small population size and is adverse to human
disturbance. We consider incidental hunting and hunting disturbances to
be factors that threaten this species throughout its range.
C. Disease or Predation
There is no available evidence indicating that disease or predation
have led to decline in caerulean paradise-flycatcher populations or
contribute to the species' risk of extinction.
D. The Inadequacy of Existing Regulatory Mechanisms
The caerulean paradise-flycatcher was declared a protected species
by the Indonesian government in January 1999 (J. C. Wardill in litt.
1999 as cited in BLI 2001a). Protected species are regulated under the
Act of the Republic of Indonesia No. 5 of 1990 Concerning Conservation
of Living Resources and Their Ecosystems (Act No. 5 1990). Under this
Act, hunting, capturing, killing, possession, or trade in protected
species or their parts is prohibited, except as permitted for research,
science, or conservation purposes (Article 21-22). Despite this law, an
analysis conducted by the IUCN (World Conservation Union) in 2003 found
that this species remained insufficiently protected (Conservation
International 2003). Lee et al. (2005) noted that Indonesia has over
``150 existing national laws and regulations to protect its wildlife
species and area * * * however, Indonesia lacks an integrated system of
law enforcement'' (p. 478). Problems include lack of awareness of
wildlife laws and inadequate monitoring capability among law
enforcement officials (Lee et al. 2005). Evidence of continued
indiscriminate hunting within the species' habitat indicates that the
caerulean paradise-flycatcher's listing as protected in 1999 has not
reduced the threat of hunting (Factor B).
The caerulean paradise-flycatcher's habitat lies within an
approximately 16 mi 2 (43 km 2) area centered on
Mt. Sahendaruman that has been designated as Protection Forest since
1994, under the jurisdiction of the Department of Forestry (Riley &
Wardill 2001). However, Whitten (2006) noted that protection forests do
not confer specific protections on the wildlife found therein; for
example, hunting is not prohibited (Whitten 2006). Thus, the species is
not adequately protected from hunting due to its presence within the
Mt. Sahendaruman Protection Forest.
Plans that began in 2001 to have the Mt. Sahendaruman Protection
Forest designated a wildlife preserve, with core areas as a strict
nature reserve (http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001),
have not been implemented (Whitten 2006). However, such a designation
might not benefit the species. According to experts, designating this
habitat as a nature reserve would shift management of the area from the
local government to the central government. This centralization of
enforcement and administration might be unresponsive or ineffective in
protecting the species and may not produce the most viable options for
long-term conservation of the species (Vidaeus 2001; Whitten 2006).
Because this designation has not been enacted, we are unable to
evaluate whether this regulatory mechanism might effectively address
the issues of habitat destruction (Factor A) and hunting (Factor B).
The species' habitat is also inadequately protected (BLI 2003a,
2004b; Conservation International 2003; Whitten 2006). There are no
strictly protected areas on the island (Riley & Wardill 2001; Whitten
2006). The Mt. Sahendaruman Protection Forest is managed for its
watershed value (Riley 2002; Riley & Wardill 2001). Although the Mt.
Sahendaruman Protection Forest contains the only remaining primary
forest on the island that is suitable for the caerulean paradise-
flycatcher (Riley & Wardill 2001), small-scale forest conversion for
agricultural purposes and non-timber forest product extraction occurs
on the fringes of the forest (see Factor A). Local rights to manage
cultivation and settlement areas within the Protection Forest are among
the key disputes between locals and the forestry department (BLI
2001a). Thus, the habitat's status as a Protection Forest does not
protect the species from threats of habitat modification.
The caerulean paradise-flycatcher has been included in a
biodiversity project, Action Sampiri. Members of the Action Sampiri
research team, Riley and Wardill, rediscovered this species in 1998
(Riley & Wardill 2001; Whitten 2006). Present-day members of Action
Sampiri (now known as Yayasan Sampiri) were contracted to develop a
public awareness program on the merits of enhancing forest protection
as part of a comprehensive conservation project for the Sangihe-Talaud
islands being implemented by BirdLife International and the World Bank,
with funding from the Global Environment Facility
[[Page 3157]]
(Whitten 2006). Conservation efforts that focus on people's awareness
of the forest and its value, including potential for ecotourism with
the prospect for local employment opportunities, are considered
important to the species' long-term conservation (BLI Indonesia Program
2001; Riley & Wardill 2001; Whitten 2006). For instance, the caerulean
paradise-flycatcher is among the endemic birds designated as island
mascots, which has promoted greater awareness of the species among
locals and has led to a general reduction in indiscriminate hunting
(http://www.rdb.or.id; BLI 2001a).
Summary of Factor D
Based on the above information, existing regulatory mechanisms are
not adequate to reduce or remove threats from habitat destruction
(Factor A) and hunting (Factor B). Encroachment and destruction along
the fringes of the species' habitat are significant current and future
threats for this species, yet the species' habitat is insufficiently
protected. Further, the lack of enforcement of protections against take
and inadequate protection within its habitat does not adequately reduce
or remove the threat of hunting. We believe that the inadequacy of
regulatory mechanisms and their enforcement are contributory risk
factors that threaten the species now and in the future.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
The caerulean paradise-flycatcher's small estimated population
size, between 19 and 135 individuals (BLI 2007d; Riley & Wardill 2001),
makes this species vulnerable to any of several risks, including
inbreeding depression, loss of genetic variation, and accumulation of
new mutations. Inbreeding can have individual or population-level
consequences by either increasing the phenotypic expression of
recessive, deleterious alleles or by reducing the overall fitness of
individuals in the population (Charlesworth & Charlesworth 1987).
Small, isolated populations of wildlife species are also susceptible to
demographic problems (Shaffer 1981), which may include reduced
reproductive success of individuals and chance disequilibrium of sex
ratios. In the absence of more species-specific life history data, a
general approximation of minimum viable population sizes is referred to
as the 50/500 rule (Soul[eacute] 1980; Hunter 1996), as described under
Factor E of the black stilt. The available information indicates that
the population of the caerulean paradise-flycatcher may be as small as
19 birds (http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001); this
is clearly below the minimum effective population size (Ne =
50 individuals) required to avoid risks from inbreeding. Moreover the
upper limit of the population estimate of no more than 135 birds
(http://www.rdb.or.id; BLI 2001a, 2007d; Riley & Wardill 2001) is a quarter of
the upper threshold (Ne = 500) required for long-term
fitness of a population that will not lose its genetic diversity over
time and will maintain an enhanced capacity to adapt to changing
conditions. As such, we currently consider the species to be at
significant risk of potential demographic shifts and lack of near- and
long-term viability.
Summary of Factor E
Demographic shifts and lack of near- and long-term viability
associated with the extant population's small size are major risks to
the caerulean paradise-flycatcher. Therefore, we consider the species'
extremely small population size and the risks associated with loss of
genetic diversity and demographic shifts to be significant factors that
threaten the caerulean paradise-flycatcher throughout its range
currently and in the future.
Conclusion and Determination for the Caerulean Paradise-Flycatcher
We have carefully assessed the best available scientific and
commercial information regarding the past, present, and potential
future threats faced by the caerulean paradise-flycatcher. We have
determined that the species is in danger of extinction throughout all
of its known range primarily due to disturbance and encroachment of its
habitat (Factor A), threats from hunting and hunting-related
disturbances (Factor B), and lack of near- and long-term genetic
viability associated with the species' small population size (Factor
E). Furthermore, we have determined that the inadequacy of existing
regulatory mechanisms to reduce or remove these threats is a
contributory factor to the risks that endanger this species' continued
existence (Factor D). Therefore, we are determining endangered status
for the caerulean paradise-flycatcher under the Act. Because we find
that the caerulean paradise-flycatcher is endangered throughout all of
its range, there is no reason to consider its status in any significant
portion of its range.
III. Giant Ibis (Pseudibis Gigantea)
Species Description
The giant ibis is a waterbird in the family Threskiornithidae. It
is native to Cambodia, Lao People's Democratic Republic (hereafter, Lao
PDR), and Vietnam. Adults stand approximately 3 ft (1 m) tall, and have
dark grey-brown plumage, with a dark hindcrown and nape. Wing-coverts
are pale gray, with darker tips. They have light red legs, a long
downward curving bill, and red eyes. Juveniles have short, black
feathers on their hindcrown and hindneck, a shorter bill, and brown
eyes (BLI 2007h).
Taxonomy
The species was first taxonomically described by Oustalet in 1877
and named Pseudibis gigantea, in the Threskiornithidae family. That
same year, Elliot placed the species in its own monotypic genus
Thaumatibis, in the same family, on the basis that the giant ibis is
much larger and less colorful than all other ibises (BLI 2007h). We
accept the species as Pseudibis gigantea, which follows the Integrated
Taxonomic Information System (ITIS 2007).
Habitat and Life History
The giant ibis requires large areas of undisturbed habitat in
deciduous dipterocarp forest and associated wetlands (Tom Clements,
Wildlife Conservation Society--Cambodia Program, Phnom Penh, Cambodia,
in litt. December 2007). It is found in open habitats (open wooded
plains, humid clearings) and deciduous forested wetlands (pools in deep
forest, lakes, swamps, seasonally flooded marshes, paddy fields) (BLI
2007h; Collar et al. 1994b; Matheu & del Hoyo 1992). The mix of dry
forest and freshwater swamp ecosystems is found only in this region
(WWF 2001, 2005). Freshwater swamp habitat is flooded at least 6 months
of the year and consists of shrubland (dominated by a nearly continuous
canopy of deciduous species, including spurges (Euphorbiaceae family)
and legumes (Fabaceae family)) and of forestland (dominated by
mangroves (Rhizophoraceae family) and melaleucas (Melaleuca spp.)). The
freshwater swamp ecosystem is found only in Cambodia and Vietnam (WWF
2001). Lower Mekong dry forests, found only in Cambodia, Lao PDR, and
Vietnam, also provide habitat to the giant ibis. These forests are
characterized by deciduous tropical hardwoods (Dipterocarpaceae family)
and semi-evergreen forest (containing a mix of deciduous and evergreen
trees) interspersed with meadows, ponds, and
[[Page 3158]]
other wetlands. Semi-evergreen forests are unique to mainland Southeast
Asia (WWF 2006b).
Although considered nonmigratory, the giant ibis will travel to
seek out permanent pools of water during the dry season (Bird et al.
2006; Matheu & del Hoyo 1992). The giant ibis may forage alone, in
pairs or in small groups (BLI 2007h). Preferring mudflats, they use
their bills to probe in the mud for a variety of seeds and small
animals, including invertebrates, small amphibians, and reptiles
(Clements et al. 2007; Davidson et al. 2002). Although considered a
wetland species, the giant ibis will also forage in dry areas; it is
believed that this is an adaptation to the lengthy dry season within
its range (http://www.rdb.or.id; BLI 2001b, 2007h; Davidson et al. 2002).
Until recently, little was known about giant ibis breeding biology,
except that the species was believed to nest in trees as other ibises
do (BLI 2007h). A nesting survey was conducted in Preah Vihear
Protected Forest (PVPF) and Kulen Promtep Wildlife Sanctuary (KPWS)
between 2004 and 2007 (Clements et al. 2007). The majority of giant
ibises bred in remote areas, sing wetlands that have a minimal human
presence (T. Clements in litt. December 2007). The number of nests
remained fairly stable over the four years of the surveys, although
their locations changed. Researchers found an average of 19 nests in
the 534-mi2 (1,383-km2) area surveyed in PVPF and
7 nests in the 726-mi2 (1,881-km2) KPWS. Fledging
success was estimated at around 50 percent, suggesting that the
population was not increasing. Researchers determined that weather and
predation were the primary limiting factors (Clements et al. 2007). See
Factor C.
The giant ibis is characterized as highly sensitive to human
disturbance (Bird et al. 2006; http://www.rdb.or.id; BLI 2001b, 2007h; T.
Clements in litt. December 2007; Clements et al. 2007; Dudley 2007;
Eames et al. 2004). Clements (in litt. December 2007) postulated that
the species' sensitivity to human populations is due to disturbance
(e.g., at feeding ponds) and incidental persecution through hunting and
poisoning of water sources (see Factors A and B).
Historical Range and Distribution
The giant ibis's historical range extended from central and
peninsular Thailand; through northern, central, and coastal regions of
Cambodia; southern and central Lao PDR; and southern Vietnam
(http://www.rdb.or.id; BLI 2001b).
A comparison of recorded observations of this species maintained by
BirdLife International (2001b) paints an erratic picture of the
``appearance'' and ``disappearance'' of the giant ibis in each range
country during the 20th century. The species has been suspected or
considered extinct in each of its range countries at least once since
it was first described in 1877. In the early part of the century, the
species was observed most often in Thailand. In the mid-1920s, the
species was seen only in Lao PDR, Cambodia, and Vietnam (http://www.rdb.or.id;
BLI 2001b). By 1992, the species was considered extant only in Vietnam
and possibly in Cambodia (Matheu & del Hoyo 1992). By the end of the
20th century, the species was considered extinct in Vietnam and
Thailand, and extant primarily in Cambodia and in Lao PDR to a lesser
extent (http://www.rdb.or.id; BLI 2001b, 2007h). Today, the species is
considered extinct only in Thailand (http://www.rdb.or.id; BLI 2001b; Matheu &
del Hoyo 1992).
Experts have noted several factors unrelated to the species' actual
status that have contributed to this erratic record: (1) The records
may not be complete because sightings may go unreported or unconfirmed
for several years (BLI 2001b; Matheu & del Hoyo 1992) (e.g., in
Vietnam, there were several unconfirmed sightings in the 1980s); (2)
nearly continuous war in the last half of the 20th century in one or
all of the range countries may have impeded expeditions to locate the
species (Matheu & del Hoyo 1992) (e.g., Cambodia experienced a nearly
50-year period of war, during which time there were only four sightings
of the species); and, (3) the habitat may be remote or the terrain
difficult to access, which might also impede opportunities to observe
the species (Duckworth et al. 1998). For these reasons, recorded
sightings (or the lack thereof) cannot be used as a basis for
concluding extinction (Butchart et al. 2006).
Specific information for each range country follows.
Cambodia: The first specimen of giant ibis was obtained in Cambodia
in 1876, but no additional sightings were reported until 1918.
Historically, the species' range spanned from the north through central
region and into the eastern portions of the country. The giant ibis was
observed several times in the 1920s and 1930s, but only four times
between 1939 and 1989 (http://www.rdb.or.id; BLI 2001b). In 1992, experts
believed the species might be extant in Cambodia, but indicated that
the recent reports had been unconfirmed (Matheu & del Hoyo 1992). The
species was observed again in 2000 (see Current Range, below).
Disturbance and hunting are two factors attributed to the species'
decline (Wildlife Conservation Society (WCS) 2007a, 2007b, 2007c).
Lao PDR: The giant ibis was not reported from Lao PDR until 1926.
Thereafter, it was observed only once each decade in the 1930s and the
1940s. Based on the paucity of sightings, it was never believed to be
common in Lao PDR (http://www.rdb.or.id; BLI 2001b). By 1992, the species was
no longer considered extant in Lao PDR (http://www.rdb.or.id; BLI 2001b;
Matheu & del Hoyo 1992), although the species was observed again the
next year (see Current range, below). Historical declines are
attributed to hunting and wetland draining or other human disturbances
(http://www.rdb.or.id; BLI 2001b).
Thailand: This species was observed in Thailand several times
between 1896 and 1913, at a time when it was not being reported in any
of the other range countries, except for one sighting in Cambodia. All
sightings were made in the southern regions of Thailand and there have
been no confirmed sightings of this species in Thailand since 1913
(http://www.rdb.or.id; BLI 2001b). From the scant sightings of this species,
researchers are uncertain whether the giant ibis was ever resident to
Thailand, or just a visitor (http://www.rdb.or.id; BLI 2001b). Since 1992, the
species has been considered extinct in Thailand, primarily due to loss
of habitat from wetland draining (http://www.rdb.or.id; BLI 2001b; Matheu &
del Hoyo 1992).
Vietnam: The species was observed once late in the 19th century and
not seen again until the mid-1920s, when it was observed several times
until 1931. By the turn of the 21st century, the giant ibis was
believed extirpated from Vietnam, with no confirmed sightings between
1931 and 2003 (http://www.rdb.or.id; BLI 2001b; Eames et al. 2004). The
species was rediscovered in 2003. Hunting is considered the primary
cause of the historical decline, and land conversion to agriculture is
a secondary cause (http://www.rdb.or.id; BLI 2001b).
Current Range and Distribution
The giant ibis' current range is the mix of dry forest and
freshwater swamp forest ecosystems of Cambodia, Lao PDR, and Vietnam;
it is considered extirpated from Thailand (BLI 2000a, 2001b;
http://www.rdb.or.id; BirdLife International--Indochina Programme (BLI-IP) &
Vietnam's Ministry of Agriculture and Rural Development (MARD) 2004;
Eames et al. 2004; World Wide Fund for Nature (WWF) 2001, 2005). Each
range country is discussed below.
[[Page 3159]]
Cambodia: Between 1992 and 2002, there were no confirmed giant ibis
sightings in Cambodia. However, since 2002, the species has been
observed at several sites throughout Cambodia. Observations in 2002 and
2003 suggest that the species continues to inhabit its historic range
in the north, central, and eastern provinces. In the Northern Plains,
the giant ibis has been observed in Stung Treng and Preah Vihar
Provinces (bordering Lao PDR), and Kratie Province (Bird et al. 2006;
http://www.rdb.or.id; BLI 2001b; Clements et al. 2007). The Northern Plains
are considered the largest remaining contiguous tract of seasonally
inundated meadows and permanent pools within a deciduous dipterocarp
forest (Davidson et al. 2002). In central Cambodia, the species has
been observed in the Tonle Sap floodplains (Kompong Thom and Siem Reap)
(http://www.rdb.or.id; BLI 2001b; Clements et al. 2007). The Tonle Sap
floodplain and associated rivers is considered one of the few remaining
remnants of freshwater swamp forest type in the region. Approximately
2,120 mi\2\ (5,490 km\2\) of the freshwater swamp forest ecoregion is
protected in Cambodia. Of this amount, the Tonle Sap Great Lake
Protected Area (which includes the Tonle Sap floodplain) makes up 2,092
mi\2\ (5,420 km\2\) of that protected habitat (WWF 2001). In eastern
Cambodia, the species has been located in the Lomphat Wildlife
Sanctuary (Mondulkiri and Rattanakiri Provinces) (Bird et al. 2006;
http://www.rdb.or.id; BLI 2001b; Clements et al. 2007; Davidson et al. 2002).
The Lomphat Wildlife Sanctuary spans a 965 mi\2\ (2,500 km\2\) area in
northeastern Cambodia (in Mondulkiri and Rattanakiri Provinces) near
the Vietnam border (WildAid 2003, 2005). The Lomphat Sanctuary is
considered to be one of the most important areas for wildlife in
Cambodia (WildAid 2005).
More recent sightings suggest that the giant ibis' range may extend
further south and east than previously understood (Bird et al. 2006).
The species has been observed in Kampot Province (the southernmost
Province in Cambodia) (http://www.rdb.or.id; BLI 2001b) and in the buffer zone
of Seima Biodiversity Conservation Area (SBCA) (Kratie and Mondulkiri
Provinces, eastern Cambodia) (Bird et al. 2006; Clements et al. 2007).
The SBCA was designated in 2002 and encompasses a 540 mi\2\ (1,400
km\2\) area (WCS 2007b).
Lao PDR: The giant ibis was believed extinct in Lao PDR in 1992
(Matheu & del Hoyo 1992). The following year, an observation was
confirmed and it has since been observed in Lao PDR several times.
Based on surveys conducted in 1998, no giant ibises were found in
central Lao PDR (Duckworth et al. 1998), indicating that the giant ibis
may no longer be present in central Lao PDR, as it was historically
(http://www.rdb.or.id; BLI 2001b). Previously suspected to be nonresident
(http://www.rdb.or.id; BLI 2001b), however in 2007 it is being reported as a
resident (BLI 2007b).
The giant ibis has been found in the open deciduous forest of two
areas in extreme southern Lao PDR: Xe Pian National Biodiversity
Conservation Area (NBCA) (Champasak and Attapeu Provinces) and Dong
Khanthung proposed NBCA (Champasak Province) (http://www.rdb.or.id; BLI 2001b,
2007b; Clements et al. 2007; Poole 2002) and giant ibis may only be a
frequent visitor to Lao PDR there from Cambodia. The Xe Pain NBCA is
927 mi\2\ (2,400 km\2\) (http://www.rdb.or.id; BLI 2001c). The Dong Khanthung
proposed NBCA has not yet been defined or approved (BLI 2007b).
Thailand: The species has not been observed in Thailand since 1913
(http://www.rdb.or.id; BLI 2001b).
Vietnam: At the turn of the 21st century, giant ibis was believed
extirpated from Vietnam, with no confirmed sightings since 1931
(http://www.rdb.or.id; BLI 2001b; Eames et al. 2004). However, in 2003,
several giant ibises were observed during surveys in Yok Don National
Park (BLI-IP & MARD 2004; Eames et al. 2004; World Wide Fund for Nature
(WWF) 2005). Located in Dok Lok Province in central Vietnam, the Park
shares a western border with Cambodia. There is some speculation that
the birds flew over the border from Cambodia (Mondulkiri Province) (WWF
2005), but this has not been confirmed or refuted.
Population Estimates
Population estimates are provided for the global population of
giant ibis as well as for each range country. The range country
estimates should not be considered distinct subpopulations. Very little
is known about the species' ecology and dispersal, and all known areas
where giant ibis have been observed are contiguous. There may be some
interchange between populations and researchers have been unable to
identify discrete subpopulations of this species (T. Clements in litt.
December 2007).
Global population estimates: The giant ibis is characterized as
uncommon and local throughout its range (Matheu & del Hoyo 1992; BLI
2000a). It occurs at relatively low densities and requires large areas
of undisturbed habitat (deciduous dipterocarp forest and associated
wetlands) (T. Clements in litt. December 2007). The majority of the
giant ibis population today is located in Cambodia, with a small number
in southern Lao PDR, even fewer in Vietnam, and no known individuals in
Thailand (BLI 2000a, 2001b; http://www.rdb.or.id; Clements et al. 2007). The
population has been conservatively estimated at a minimum of 100 pairs,
with no more than 250 total individuals (Clements et al. 2007).
Cambodia: Population surveys have been conducted in several areas
since the giant ibis' rediscovery in Cambodia in 2000. Aerial surveys
between 2000 and 2001 indicated that between 50 birds and 90 were
located in the Northern Plains (BLI-IP & MARD 2004). Based on the nest
surveys conducted between 2004 and 2007 in Preah Vihear Protected
Forest (PVPF) and Kulen Promtep Wildlife Sanctuary (KPWS), also in the
Northern Plains, there was evidence of 28 nesting pairs of birds
(Clements et al. 2007). Extrapolating to the available suitable habitat
within the Northern Plains (including the Tonle Sap Lake), researchers
estimated the population in the Northern Plains at 30 to 40 pairs. In
the Eastern Plains (including the Siema Biodiversity Conservation Area
(SBCA) and the Lomphat Wildlife Sanctuary), the population has been
estimated at no more than 10 to 20 pairs. In northeastern Cambodia,
Siem Pang (Stung Treng Province) surveys suggest that an excess of 14
pairs may exist. The total giant ibis population in Cambodia, based on
available suitable habitat, is 82 to 100 pairs (Clements et al. 2007).
Lao PDR: The giant ibis Laotian population is estimated to include
no more than 5 to 10 pairs of birds (Clements et al. 2007).
Vietnam: In 2003 and 2004, several giant ibises were observed
during surveys in Yok Don National Park (Don Lok Province), the only
known location within Vietnam (BLI-IP & MARD 2004; Eames et al. 2004;
World Wide Fund for Nature (WWF) 2005). Yok Don National Park, which
occupies a 446-mi\2\ (1,155-km\2\) area, became a protected area in
1986 and a national park in 1991. The forest has three use areas: A
312-mi\2\ (809-km\2\) strict protection area, a 117-mi\2\ (3,043-km\2\)
forest rehabilitation area, and a 16-mi\2\ (42-km\2\) administration
and services area. In addition, a 517-mi\2\ (1,339-km\2\) buffer zone
has been defined (Eames et al. 2004). However, these protections are
ineffective at reducing or removing threats directed at the species
(see Factor D).
Eames et al. (2004) postulated that the species is either very rare
or a visitor in Vietnam. The Yok Don area is contiguous with sites in
Cambodia (such
[[Page 3160]]
as Eastern Mondulkiri) that are known to support resident breeding
birds of giant ibises (T. Clements in litt. December 2007). During the
re-evaluation of the species' status, experts concluded that Yok Don
National Park is unlikely to support any breeding pairs (Clements et
al. 2007). They considered that the birds observed within the Park were
likely to be foraging or dispersing birds and that it was unlikely that
the Park ``supported resident breeding birds due to the high level of
disturbance and hunting'' (T. Clements in litt. December 2007).
Conservation Status
Global conservation status: Using the IUCN categories, the global
population of giant ibis falls within the range of 50 to 250
individuals (BLI 2007h). The recent rediscovery of giant ibis in
Vietnam and additional populations in Cambodia prompted BirdLife to re-
evaluate the species' status in 2007 (Jez Bird, Global Species
Programme Assistant, BirdLife International, in litt. November 2007;
BirdLife Globally Threatened Species Forum 2007). They concluded that,
despite recent new sightings of giant ibis in Vietnam and Cambodia,
there was insufficient evidence to confirm that the giant ibis
population exceeds 250 individuals (Clements et al. 2007; J. Bird in
litt. November 2007).
The giant ibis has been categorized by the IUCN as a ``Critically
Endangered'' since 1994 (BLI 2004c). BirdLife International, which
serves as the IUCN Red List authority for birds, re-evaluated the
status of the species in 2007 and decided to retain its critically
endangered status for the 2008 Red List (J. Bird in litt. November
2007; Clements et al. 2007).
Cambodia: In 2005, the giant ibis was declared the national
symbolic bird in Cambodia (Chheang Dany, Deputy Director, Wildlife
Protection Office, Phnom Penh, Cambodia, in litt. January 2007) and, as
of 2007, the species had been proposed as endangered in the draft
wildlife list in Cambodia, the highest protected species category by
the Forestry Law of 2002. However, this regulatory mechanism is
ineffective at reducing or removing threats directed at the species
(see Factor D).
Lao PDR: In Lao PDR, the giant ibis is legally protected and
receives some habitat protection in the Xe Pian National Biodiversity
Conservation Area (NBCA) (http://www.rdb.or.id; BLI 2001b). However, these
regulatory mechanisms are ineffective at reducing or removing threats
directed at the species (see Factor D).
Vietnam: In Vietnam, the species is listed as endangered (Eames et
al. 2004). However, this regulatory mechanism is ineffective at
reducing or removing threats directed at the species (see Factor D).
Summary of Factors Affecting the Giant Ibis
Where applicable in the sections below, factors affecting the
survival of the giant ibises are discussed in two parts: (1) Regional
factors (affecting or including two or more range countries), and (2)
Factors within individual range countries.
A. The Present or Threatened Destruction, Modification, or Curtailment
of the Species Habitat or Range
Giant ibis is affected throughout its range by (1) habitat
modification from dam construction, (2) deforestation caused by war,
(3) illegal logging and wood fuel collection, (4), and continued human
encroachment (Bird et al. 2006; BLI 2007h; T. Clements in litt.
December 2007; Clements et al. 2007; Poole 2002; WWF 2001, 2005).
(1) Habitat modification from dam construction: Dam construction
along the Mekong River Basin (MRB) has altered giant ibis habitat
throughout its range. The MRB begins as a system of tributaries and
streams originating in the Tibetan Plateau and flowing eventually into
the Mekong River Delta, 2,000 mi (4,800 km) from start to finish.
Including parts of China, Myanmar and Vietnam, nearly one-third the
land area of Thailand, and most of Cambodia and Lao PDR, the MRB
encompasses a 307,000 mi\2\ (795,000 km\2\) area. The Lower Mekong
River Basin (LMRB) includes Cambodia, Lao PDR, Thailand, and Vietnam
(Mekong River Commission (MRC) 2007). According to the Asian
Development Bank (ADB 2005), 13 dams are built, being built, or
proposed to be built along the Mekong River Subregion. This important
regional resource has a profound influence on each of the diverse
ecosystems through which it flows, including giant ibis habitat. Two
examples are discussed.
Construction of Yali Falls hydroelectric dam began in Vietnam in
1993 and was completed in 1999. The 226-ft (69-m) high dam was
constructed at Yali Falls, on a tributary of the Sesan River. Part of
the LMRB, the Sesan River originates in Vietnam and flows through
Cambodia, where it meets the Mekong River. The Mekong River, in turn,
flows into the Tonle Sap floodplain (Center for Natural Resources and
Environmental Studies (CRES) 2001). The Tonle Sap floodplain, currently
the southernmost extreme of the giant ibis' range in Cambodia, and
freshwater swamp forest ecosystem rely on the Mekong River as part of
its seasonal cycle of flooding (WWF 2001). A study of the impact of
this dam on downstream communities in 2001 found that the effect of the
dam on humans (including resettlement, drowning in unexpected floods,
and livelihood changes especially for fishermen) would be ``significant
but manageable,'' by relocating communities inland, for instance. The
report also noted no anticipated impacts on waterbirds (CRES 2001).
However, the study did not look beyond Vietnam and the effects of water
flow disruption further downstream, including Tonle Sap floodplain in
Cambodia. Within the first year of the dam's completion, massive
devastating floods were reported downstream (CRES 2001).
Dam construction along the Srepok River, which flows through giant
ibis habitat in Vietnam and Cambodia, has also altered the species'
habitat. Construction of the Buon Koup Dam began in 2003 (San et al.
2007), altering the natural water and vegetation patterns along the
Srepok River, affecting Yok Don National Park (Eames et al. 2004). A
draft environmental impact analysis (EIA) identified several impacts to
people living along the Cambodian side of the river, including daily
irregular water fluctuations, erosion of riverbanks, and water
pollution, as well as impacts on paddy production, fish migration,
fishing livelihoods, and species diversity (San et al. 2007). In
response to unpredictable water levels and flash flooding caused by
dams, people began moving inland (ADB 2005).
Dam construction along the MRB has diverted water from critical
ecosystems and has altered or threatens to alter the natural water and
vegetation along waterways within the Mekong River Delta, a vital water
source throughout the species' range. Impacts include drastic water
level fluctuations, frequent flooding, and reduced water levels during
the dry season, as well as the potential for riverbank erosion and
increased water pollution. As populations move further inland to escape
the unpredictable changes caused by dam construction, they encroach
upon inland forested areas, including freshwater swamp ecosystems and
semi-evergreen forests, which serve as giant ibis habitat (See (4)
Continued human encroachment, below). The giant ibis is adverse to
human disturbance (Bird et al., 2006; http://www.rdb.or.id; BLI 2001b, 2007h;
Dudley 2007; Eames et
[[Page 3161]]
al., 2004), and increased human disturbance exacerbates the impact of
habitat modification caused by dam construction. See also (4) Continued
human encroachment, below.
(2) Deforestation from war: The entire range of the giant ibis was
severely affected by deforestation resulting from the Vietnam War (1959
to 1975). Bombing, herbicide spraying, and land-clearing activities
were undertaken during the War. According to Westing (2002), 13.8
million U.S. tons (14 million metric tons) of high-explosive munitions
were dropped by the United States throughout the region, including 5
percent in Cambodia, 16 percent in Lao PDR, 8 percent in northern
Vietnam, and 71 percent in southern Vietnam, targeting primarily rural
areas. Between 18 to 19 million gallons (gal) (68 to 72 million liters
(l)) of herbicides (including Agent Orange contaminated with dioxin
(see Factor E)) were sprayed on the region (Schechter et al., 2001;
Westing 2002). Of this amount, less than 0.1 percent was sprayed in
Cambodia, 2 percent in Lao PDR, negligible amounts in northern Vietnam,
and over 98 percent in southern Vietnam. Finally, 3 percent (1,255
mi\2\ (3,250 km\2\)) of the total forested area in South Vietnam was
plowed over with tractors (Westing 2002). Inland forested areas,
including freshwater swamp ecosystems and semi-evergreen forests, which
serve as giant ibis habitat, were especially affected by herbicide
applications during the war, where up to 77 percent of the total
spraying occurred (Boi 2002). The most affected areas of bombing,
spraying, and bulldozing correspond with the historic range of the
giant ibis, where the species went unobserved until 1993, and the
figures for southern Vietnam are particularly informative, where the
species remains unobserved to this day (http://www.rdb.or.id; BLI 2001c).
(3) Illegal logging and wood fuel collection: The open and
deciduous forested wetland habitats preferred by the giant ibis species
have diminished over much of Indochina, and only Cambodia retains
significant portions of this habitat (WWF 2005). Deforestation from
illegal logging and wood fuel collection has reduced the number of
nesting sites available to the species (BLI 2007h; Poole 2002). In
addition, it led to increased habitat disturbance (see (4), Continued
human encroachment).
Cambodia: Poole (2002) reported that large nesting trees around
Cambodia's Tonle Sap floodplain, particularly crucial to ibises for
nesting, are under increasing pressure by felling for firewood and
building material. Illegal logging has been reported in Trapeang Boeung
(Global Witness 2007), where the giant ibis was observed in 2003
(http://www.rdb.or.id; BLI 2001b), and in the SBCA, where the species was
observed in 2006 (Bird et al., 2006).
Lao PDR: Logging has been reported in the Xe Pian National
Biodiversity Conservation Area (NBCA), where the giant ibis has been
observed, perhaps as a seasonal visitor (Robichaud et al., 2001).
In Vietnam: Deforestation in Vietnam has been significant
throughout the 20th century. In 1943, approximately 43 percent of the
total land area in Vietnam was covered by natural forest. This
corresponded to 54,054 mi\2\ (140,000 km\2\). By 1945, 22,007 mi\2\
(57,000 km\2\) of natural forest had been cleared (Brown et al., 2001).
By 1990, the total forested area had been reduced to 27 percent, nearly
half the amount of 1943 (Boi 2002).
Logging bans in Vietnam became progressively more pervasive in the
1990s. In 1992, logging in watershed and special-use forests was
banned. In 1999, all commercial logging in natural forests in the
northern highlands and midlands, the southeast, and in the Mekong River
and Red River Delta Provinces was banned. As of 2001, 58 percent of
Vietnam's natural forests were covered by the ban (Brown et al., 2001).
(See Factor D.)
The government planned to obtain its wood needs from plantation
forests (Brown et al., 2001). In 1999, the total forested area had
increased to 33 percent, corresponding to 36,464 mi\2\ (94,440 km\2\).
This figure included 5,680 mi\2\ (14,710 km\2\) of plantation forest,
only 1 percent of which represented deciduous forest (Boi 2002). The
increase in plantations forests led to changes in species composition.
Changes in species composition led to changes in the amount of
forest cover. Following the Food and Agriculture Organization's (FAO)
classifications for forest cover, Cuong (1999) determined from remote
sensing data that, between 1943 and 1995, forest cover in Vietnam
transformed from 43 percent cover (which considered to be medium forest
cover by FAO), to 28 percent (which FAO considers to be open forest).
(4) Continued human encroachment: Habitat alteration from dam
construction and destruction caused by war are compounded by human
encroachment throughout the species' range (see also (2), Factors
within individual range countries, below).
Cambodia: In Cambodia's Tonle Sap floodplain, the effects of dam
construction are exacerbated by agricultural conversion (Eames et al.
2004). Tonle Sap floodplain is considered ``prime rice-growing
habitat'' (WWF 2001, p. 1). Extensive cultivation during the dry season
and the impacts from fishing communities along the delta, disrupt the
natural water cycle, resulting in drastic water level fluctuations
within the Mekong River Delta, with frequent flooding and lower water
levels during the dry season (WWF 2001).
The buffer zone of Cambodia's Seima Biodiversity Conservation Area
(SBCA) (Kratie and Mondulkiri Province), where giant ibis was observed
in 2006 (Bird et al. 2006), is threatened by a variety of human
activities, including road building, increased subsistence activities,
and collection of non-timber forest products (Bird et al. 2006; WCS
2007b). Resin tapping is common throughout the SBCA, and the
concomitant increase in the number of people entering the SBCA to
undertake this and other extractive activities poses an additional
threat to the giant ibis (Bird et al. 2006), which is highly sensitive
to human disturbance (Bird et al. 2006; http://www.rdb.or.id; BLI 2001b,
2007h; T. Clements in litt. December 2007; Clements et al. 2007; Dudley
2007; Eames et al. 2004).
Lao PDR: Robichaud et al. (2001) identified the following ongoing
internal and external threats to giant ibis habitat in the Xe Pian
National Biodiversity Conservation Area (NBCA): (1) Subsistence
agriculture, (2) subsistence hunting, (3) trade hunting, (4)
subsistence fishing, (5) trade fishing, (6) free-ranging livestock, (7)
road construction, and (8) infrastructure development.
Vietnam: Giant ibis habitat in Vietnam's Yok Don National Park is
threatened by road building, road improvements, and artificial
waterhole creation on sites of natural ``trapeangs'' (seasonal and
permanent waterholes). Giant mimosa (Mimosa pigra) has spread rapidly
along the Srepok River since the 1980s (Eames et al. 2004). Giant
mimosa is an aggressively invasive plant that forms dense thickets,
closing formerly open habitats and outcompeting native species (WWF
2001).
The giant ibis requires large areas of undisturbed habitat and is
known to be highly sensitive to human disturbance (Bird et al. 2006;
http://www.rdb.or.id; BLI 2001b, 2007h; T. Clements in litt. December 2007;
Clements et al. 2007; Dudley 2007; Eames et al. 2004). In the nesting
surveys conducted between 2004 and 2007, researchers found that the
most nests were located more than 3 mi (5 km) from villages (Clements
et al. 2007). Bird et al. (2006) studied the effect of habitat
disturbance on several large waterbirds, including the giant
[[Page 3162]]
ibis. They found that the giant ibis was significantly less likely to
visit watering holes that were frequented by humans. The majority of
the species breeds in remote areas and uses wetlands that have minimal
human presence (T. Clements in litt. December 2007).
Habitat fragmentation caused by loss of habitat is compounded by
human disturbance and is likely to have a disproportionate effect on
the remaining individuals (Clements et al. 2007). According to Clements
(in litt. December 2007), continuing expansion of human settlements and
wetland manipulation are likely to cause strong declines over time,
even if deforestation rates are low.
Summary of Factor A
Giant ibis habitat has been destroyed and degraded throughout the
core of its range, and habitat reduction or modification continues to
be a significant factor endangering the species. The giant ibis is a
waterbird that seeks out permanent sources of water, and the impacts
from habitat destruction and alteration are exacerbated by its aversion
to human disturbance. Dam construction has contributed to habitat
alteration on a regional scale along waterways within the Mekong River
Delta (a vital water source throughout the species' core range) and
contributes to unpredictable water fluctuations and changes in human
activity along the waterways. The effects of flooding are exacerbated
by extensive cultivation during the dry season and the impacts from
fishing communities along the delta. Habitat loss through wetland
drainage for agricultural purposes has reduced foraging and roosting
areas. Logging has been reported in giant ibis territory in each range
country, and deforestation reduces the number of trees available to the
species as nesting sites. Expansion of human settlements and conversion
of wetland areas to agriculture continue throughout the species' known
range. The encroachment of nesting sites and foraging areas is
compounded by human disturbance and may disproportionately promote
fragmentation of remaining individuals. Based on the above information,
we find that the present or threatened destruction, modification, or
curtailment of the giant ibis' habitat or range is a significant on-
going and future risk to the species.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
(1) Overutilization within the region: The giant ibis is
susceptible to hunting for consumption and disturbance caused by
hunting other species throughout its range (Bird et al. 2006;
http://www.rdb.or.id; BLI 2001b, 2007h; T. Clements in litt. December 2007;
Desai & Luthy 1996; Eames et al. 2004; Poole 2002; WCS 2007a, 2007b,
2007c). There have been reports of severe hunting pressures on large
mammals and waterbirds, including giant the ibis, throughout the
species' range (ADB 2005; T. Clements in litt. December 2007; Desai &
Luthy 1996; Poole 2002; United Nations Environment Programme-Strategic
Environment Framework (UNEP-SEF) 2005; WCS 2007a, 2007b, 2007c). In
2005, the United Nations Environment Programme-Strategic Environment
Framework (UNEP-SEF 2005) reviewed major threats to biodiversity,
including giant ibis, within the Greater Mekong Sub-region (including
Cambodia, Lao PDR, Myanmar, Thailand, and Vietnam). They found that,
after habitat loss, the second greatest threat to endangered wildlife
in the region was hunting and gathering. Giant ibises are particularly
vulnerable to hunting during the dry season, when they seek out
permanent water sources and are more likely to encounter people seeking
out these same water resources (BLI 2007h).
Given the species' small estimated global population size (a
minimum of 100 pairs, but no more than 250 total individuals (Clements
et al. 2007)), any hunting would be detrimental to the species'
continued existence. Highly sensitive to human disturbance, giant
ibises are negatively affected by disturbance from hunting-related
activities, even when they are not directly targeted (T. Clements in
litt. December 2007).
(2) Overutilization within individual range countries:
Cambodia: Cambodia is the core of the species' range, where the
total Cambodian giant ibis population is estimated to be 82 to 100
pairs (Clements et al. 2007). Subsistence hunting is a challenge to
wildlife protection in Cambodia, where the average annual income is
US$268 and ``95 percent of the country lives from tree cutting and
wildlife hunting'' (WildAid 2002, p. 1). According to Clements (in
litt. December 2007), in surveys conducted over the past eight years,
there have been occasional reports of giant ibis being hunted for
personal or commercial use in Cambodia, but ``it [giant ibis] appears
to have little value wildlife trade.'' In the past 5 years, Clements
(in litt. December 2007) is aware of two instances of giant ibis
hunting, both for personal consumption. In addition, locals poison
waterholes, using commonly available herbicides, fertilizers, or
insecticides, to hunt fish and sometimes to poison large waterbirds for
consumption (T. Clements in litt. December 2007).
Poole (2002) noted that bird species in Cambodia are generally
susceptible to indiscriminate hunting and egg collection. A 1996
wildlife survey of three sites within Mondulkiri and Rattanakiri
Provinces, where Lomphat Wildlife Sanctuary is located and wherein the
giant ibises have been observed, revealed that hunting was extensive
and intense (Desai & Vuthy 1996). The Wildlife Conservation Society
reported hunting as the single largest threat to wildlife in the
Northern Plains (WCS 2007a). Subsistence and commercial hunting of a
variety of animals has been reported in within the SBCA as recently as
February 2006 (Bird et al. 2006; WCS 2007b), and collection of eggs and
chicks from nests threaten large waterbirds in the Tonle Sap floodplain
(Clements et al. 2007; WCS 2007a, 2007b, 2007c). See also Factor D.
Lao PDR: BirdLife International (2006a) reports that hunting in Lao
PDR has severely impacted most large waterbirds. While we have no
information that the giant ibis is specifically targeted, this practice
would severely threaten the species in Lao PDR, where the giant ibis
population is unlikely to exceed 5 to 10 pairs (Clements et al. 2007).
Vietnam: Large mammals and waterbirds are particularly vulnerable
to hunting within Yok Don National Park, the only location within
Vietnam where giant ibis has been observed (Eames et al. 2004), and
wildlife hunting continued to be a problem within the Yok Don National
Park in 2005 (Eames et al. 2005) (see also Factor D). The U.S.
Department of State (DOS) reported that Vietnam's wildlife, including
endangered birds, is threatened by illegal export to China (DOS Cable
2007). However, we have no specific information that the giant ibis is
part of such trade. The species is not known to be in international
trade and has not been formally considered for listing under CITES
(http://www.cites.org).
Summary of Factor B
Indiscriminate hunting threatens giant ibis throughout its range.
Giant ibises are especially accessible and more vulnerable to hunting
at the height of the dry season when they are concentrated around
available waterholes. The species' aversion to human disturbance makes
it more vulnerable to disruption from hunting-related activities. Given
their small population numbers (estimated to be
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100 pairs at minimum, but no more than 250 individuals) and the
apparent inadequacies in enforcement (Factor D), we consider incidental
killing from hunting and hunting disturbances to be factors that
threaten this species throughout its range.
C. Disease or Predation
According to the Deputy Director of the Wildlife Protection Office
in Cambodia (C. Dany in litt. January 2007), highly pathogenic avian
influenza (HPAI) H5N1 continues to be a serious problem. This strain of
avian influenza first appeared in Asia in 1996 and spread from country
to country with rapid succession (Peterson et al. 2007). By 2006, the
virus was detected across most of Europe and in several African
countries. Influenza A viruses, to which group strain H5N1 belongs,
infect domestic animals and humans, but wildfowl and shorebirds are
considered the primary source of this virus in nature (Olsen et al.
2006), particularly wild birds of wetland and aquatic environments
(Peterson et al. 2007). Although the Wildlife Protection Office noted
that the U.S. Department of Agriculture Animal and Plant Health
Inspection Service were helping train field staff on surveillance
techniques, Cambodia lacks an avian influenza wild bird surveillance
program (C. Dany in litt. January 2007). According to Dany (in litt.
January, November 2007), scientists are not sure how many wild bird
species carry or are infected by AI, and it is possible that giant ibis
may be a carrier. However, a comprehensive study has not yet been
undertaken. Lack of an avian influenza wild bird surveillance program
in Cambodia will make it difficult to resolve whether giant ibis is a
carrier.
Until recently, there was no information on predation affecting the
giant ibis, and there is still very little known about giant ibis
breeding ecology and dispersal (T. Clements in litt. December 2007).
However, recent research suggests that predation impacts the largest
known concentration of giant ibises in Cambodia's Northern Plains
(estimated to be 30 to 40 pairs of birds), representing between one-
third to one-fourth of the total known population (Clements et al.
2007). Nesting surveys were conducted between 2004 and 2007, and the
giant ibis' fledging success was estimated at 50 percent. Researchers
determined that predation had negatively impacted the giant ibis'
fledging success. Predation by crows (Corvus macrorhynchos), macaques
(Macaca sp.), hawks (species unknown), civets (Cynogale sp), and
martins (species unknown) was identified as a major contributor to the
species' low fledging success (Clements et al. 2007). Given the
species' small global population size and that the Northern Plains
species may represent up to one-fourth of the known giant ibis
population, we consider this level of predation to be a significant
factor that threatens the species' continued existence.
Summary of Factor C
While the avian flu may be a threat to giant ibises, there is no
evidence that known populations are currently infected. Potential for
disease outbreaks warrants monitoring (see Factor D) and may become a
more significant threat factor in the future. However, we find that
disease is not a risk to the giant ibis at this time.
Predation by crows, macaques, hawks, civets, and martins threatens
the largest known concentration of giant ibises and contributes to the
species' low fledging success (estimated to be only 50 percent). Given
the risks associated with small population sizes, further reductions in
population numbers jeopardizes the species' viability and resiliency to
adapt to changing conditions (see Factor E). We consider predation to
be a factor that endangers the species.
D. The Inadequacy of Existing Regulatory Mechanisms
(1) Regional regulatory mechanisms:
The Mekong River Commission (MRC) was formed between the
governments of Cambodia, Lao PDR, Thailand, and Vietnam in 1995 as part
of The Agreement on the Cooperation for the Sustainable Development of
the Mekong River Basin. The signatories agreed to jointly manage their
shared water resources and economic development of the river (MRC
2007). In 2003, the governments of Cambodia, China, Lao PDR, Myanmar,
Thailand, and Vietnam committed to cooperate on developing a regional
power grid (via hydroelectric dams), among other things, under the
Asian Development Bank's Greater Mekong Subregion Program
(International Rivers Network. 2004). However, according to the
International Rivers Network (2004), the master plan to create the
regional power grid did not thoroughly assess the impacts to
communities, fisheries, Forests or nature reserves. The cooperative
efforts have had little impact on the dams being built in the Mekong
River Region or on broader decision-making processes within the Region
(CRES 2001). According to the Asian Development Bank, 13 dams have been
built, are being built, or are proposed to be built along the Mekong
River Subregion (ADB 2005). The continued modification of giant ibis
habitat has been identified as a primary threat to this species (Factor
A), and this regional regulatory mechanism is not effective at reducing
that threat.
(2) Regulatory mechanisms within individual range countries:
Cambodia: Several laws exist in Cambodia to protect the giant ibis
from two of the primary threats to the species, habitat destruction
(Factor A) and hunting (Factor B). However, they are ineffective at
reducing those threats. In Cambodia, Declaration No. 359, issued by the
Ministry of Agriculture, Forestry and Fisheries in 1994, prohibited the
hunting of giant ibis. However, reports of severe hunting pressure
within the giant ibis' habitat and illegal poaching of wildlife in
Cambodia continue (Bird et al. 2006; Desai & Luthy 1996; FFI 2000;
Poole 2002; UNEP-SEF 2005; WCS 2007a, 2007b, 2007c).
Joint Declaration No. 1563, On the Suppression of Wildlife
Destruction in the Kingdom of Cambodia, was issued by the Ministry of
Agriculture, Forestry and Fisheries in 1996. However, JICA (1999)
reported that this regulatory measure was ineffectively enforced. In
2000, survey work conducted by Fauna and Flora International in
collaboration with the Government of Cambodia, Ministry of Environment
and Wildlife Protection Office, found evidence of illegal hunting of a
variety of animals and noted a flagrant disregard for the illegality of
this activity: ``Hunters and dealers freely displayed the illegal
materials and readily provided any details requested,'' indicating a
lack of wildlife laws awareness or inadequate law enforcement (FFI
2000).
The Forestry Law of 2002 strictly prohibited hunting, harming, or
harassing wildlife (Article 49) (Law on Forestry 2003). This law
further prohibited the possession, trapping, transport, or trade in
rare and endangered wildlife (Article 49). As of 2007, Dany (in litt.
January 2007) noted that the species had been proposed as endangered in
the draft wildlife list in Cambodia, the highest protected species
category by Forestry Law 2002 (Law on Forestry 2003). However, to our
knowledge, Cambodia has not yet published a list of endangered or rare
species. Thus, this law is not currently effective at protecting the
giant ibis from threats by hunting (Factor B).
The Creation and Designation of Protected Areas regulation
(November 1993) established a national system of protected areas. In
1994, through Declaration No. 1033 on the Protection
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of Natural Areas, the following activities were banned in all protected
areas: (1) Construction of saw mills, charcoal ovens, brick kilns, tile
kilns, limestone ovens, tobacco ovens; (2) hunting or placement of
traps for tusks, bones, feathers, horns, leather, or blood; (3)
deforestation; (4) mining minerals or use of explosives; (5) use of
domestic animals, such as dogs; (6) dumping of pollutants; (7) the use
of machines or heavy cars which may cause smoke pollution; (8) noise
pollution; and (9) unpermitted research and experiments. In addition,
the Law on Environmental Protection and Natural Resource Management of
1996 (Law on Environmental Protection and Natural Resource Management
1996) sets forth general provisions for environmental protection. Under
Article 8 of this law, Cambodia declares that its natural resources
(including wildlife) shall be conserved, developed, and managed and
used in a rational and sustainable manner. Several protected areas have
been established within the range of the giant ibis, including the
Tonle Sap Great Lake Protected Area, Seima Biodiversity Conservation
Area, and Lomphat Wildlife Sanctuary.
The Tonle Sap Great Lake protected area was designated a Multiple
Use Management Area in 1993 through the Creation and Designation of
Protected Areas Decree (Creation and Designation of Protected Areas
1993). Under this decree, Multiple Use Management Areas are those areas
which provide for the sustainable use of water resources, timber,
wildlife, fish, pasture and recreation with the conservation of nature
primarily oriented to support these economic activities. In 1997, the
Tonle Sap region was designated a UNESCO ``Man and Biosphere'' site. To
echo the United Nations designation, the Cambodian government developed
a National Environmental Action Plan (NEAP) in 1997, supporting the
UNESCO site goals. Among the priority areas of intervention are
fisheries and floodplain agriculture at Tonle Sap Lake, biodiversity
and protected areas, and environmental education. NEAP was followed by
the adoption of the Strategy and Action Plan for the Protection of
Tonle Sap (SAPPTS) in February 1998, and the issuance of a Royal Decree
officially making Tonle Sap Lake a Biosphere Reserve on April 10, 2001
(Tonle Sap Biosphere Reserve Secretariat 2007). In 2006, the Cambodian
government created Integrated Farming and Biodiversity Areas (IFBA),
including 115 mi2 (300 km2) near Tonle Sap Lake,
to protect the distinctive flora in that region (WWF 2006a). The above
measures have focused attention on the conservation situation at Tonle
Sap and have begun to improve the conservation situation there, but
several management challenges remain, including overexploitation of
flooded forests and fisheries; negative impacts from invasive species;
lack of monitoring and enforcement; low level of public awareness of
biodiversity values; and uncoordinated research, monitoring, and
evaluation of species' populations (Matsui et al. 2006; Tonle Sap
Biosphere Reserve Secretariat 2007).
The Seima Biodiversity Conservation Area was established through
Declaration 260.12-08-2002 (On the Establishment of Seima Biodiversity
Conservation Area in Samling Forest Concession in Mondul Kiri and
Kratie Provinces). However, threats at this site remain. Lack of clear
land and resource tenure within the buffer zone of Seima Biodiversity
Conservation Area (SBCA) (Kratie and Mondulkiri Province), where giant
ibises were observed in 2006 (Bird et al. 2006), has resulted in
influxes of squatters interested in claiming, cutting, or clearing the
land (WCS 2007b). In early 2006, during surveys of the Seima
Biodiversity Conservation Area (SBCA), where giant ibis is located,
researchers encountered hunters ``with no law enforcement in
operation'' (Bird et al. 2006, p. v).
The Lomphat Wildlife Sanctuary, where the giant ibis is also found,
was established in 1993 through the Creation and Designation of
Protected Areas Decree (Creation and Designation of Protected Areas
1993) and is considered to be one of the most important areas for
wildlife in Cambodia (WildAid 2005). Under this decree wildlife
sanctuaries are considered natural areas where nationally significant
species of flora and fauna, natural communities, or physical features
require specific intervention for their perpetuation (Creation and
Designation of Protected Areas 1993). In 2003 and 2004, the Service's
Rhino and Tiger Conservation Fund supported the Lomphat Conservation
Project (LCP), which has a long-term goal of assisting rangers and
field staff in the conservation of the Sanctuary's living resources,
including giant ibis. Six teams of rangers were trained during the
duration of the LCP, and the Sanctuary began instituting patrols on at
least 15 days per month. The rangers have been extremely efficient in
locating poachers, illegal loggers, and entire camps set aside for
poachers. Educational materials were developed and tailored to the
villagers' patterns of use of the local resources (WildAid 2003), and
villagers have demonstrated a keen interest in offering information to
protect their resources and assist the rangers. Extensive public
outreach has improved conservation awareness throughout the Sanctuary
and around its borders (WildAid 2005). Project leaders for the Lomphat
Conservation Project indicated that great strides have been made in
training rangers and combating poaching, although community outreach
required more effort (WildAid 2005). In 2005, the giant ibis was
declared the national symbolic bird in Cambodia (C. Dany in litt.
January 2007), which may help to raise public awareness as to the need
to conserve the species and its habitat.
Giant ibis habitat within Cambodian protected areas faces several
challenges. The legal framework governing wetlands management is
institutionally complex, resting upon legislation vested in government
agencies responsible for resource use (Fishery Law 1987), land use
planning (Land Law 2001), and environmental conservation (Environmental
Law 1996, Royal Decree on the Designation and Creation of National
Protected Areas System 1993) (Bonheur et al. 2005). Furthermore, the
country's wildlife protection office lacks the staff, technical ability
and monetary support to conduct systematic surveys on the giant ibis
(C. Dany in litt. January 2007). This, in turn, leads to ineffective
monitoring and enforcement, and, consequently, resource use goes
largely unregulated (Bonheur et al. 2005). Thus, the protected areas
system in Cambodia is ineffective in removing or reducing the threats
of habitat modification (Factor A) and hunting (Factor B) faced by the
giant ibis.
Lao PDR: Giant ibis is legally protected in Lao PDR (Eames et al.
2004). In Lao PDR, the giant ibis is found in one protected area, the
Xe Pian National Biodiversity Conservation Areas (NBCA). Regulation No.
0524/MAF.2001, on NBCAs and wildlife management, was issued by the
Ministry of Agriculture and Forestry on June 7, 2001 (Robichaud et al.
2001). This regulation is a comprehensive code of wildlife protection.
Penalties for violation of the existing decrees and instructions are
outlined in the Penal Code of the Lao PDR (October 23, 1989) and
refined in the Instructions for the Implementation of Decree No. 118
and in the Forestry Law of 1996.
Xe Pian NBCA was established in 1993 as part of the system of
National Protected Areas. Long-term biodiversity conservation is the
primary objective of NBCAs, according to PM Decree 164 and the 1996
Forestry Law. While the establishment of this protected area represents
a positive step toward
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conserving habitat in Xe Pian, the protection afforded giant ibis in
the Xe Pian NBCA is marginal to ineffective due to confusion over
management authority and lack of enforcement (http://www.rdb.or.id; BLI 2001c,
2001d; Rauchibauld et al. 2001). Furthermore, the existence of an NBCA
does not rule out construction of hydroelectric dams, or commercial
activities such as logging (http://www.rdb.or.id; BLI 2001d), identified as
threats to this species (Factor A).
Thailand: The species is currently considered extirpated from
Thailand. However, giant ibis is protected by the Wildlife Animal
Reservation and Protection Act (WARPA) (B.E. 2535 1992; Eames et al.
2004). Under WARPA, hunting is prohibited (section 16), as is
possession of carcasses (section 19), trade (section 20), and
collection, harm or possession of nests (section 21). Violations of
sections 16, 19, or 20 of WARPS may result in imprisonment not
exceeding four years or fines nor exceeding 40,000 baht (Thai dollars),
or both. Violations of section 21 of WARPA may result in imprisonment
not exceeding one year or fines not exceeding 6,000 baht. This
protection may help to remove the threat of hunting, which affect the
species throughout its existing current range (Factor B), but does
nothing to remove or reduce the threat to habitat reduction (Factor A),
which was attributed as the primary cause for the species' extinction
in Thailand (http://www.rdb.or.id; BLI 2001b; Matheu & del Hoyo 1992).
Vietnam: Decree No. 32/2006/ND-CP of March 30, 2006, on Management
of Endangered, Precious, and Rare Forest Plants and Animals,
establishes a list of endangered species and protections afforded to
those species (Decree No. 32 2006). However, the giant ibis is not on
that list (Official Dispatch No. 3399 2002) and therefore is not
afforded any legal protection under this Decree.
Vietnam banned hunting without a permit in 1975 (Zeller 2006).
However, the Department of State (DOS Cable 2007) reports that
Vietnam's wildlife, including birds, continues to be susceptible to
domestic consumption.
Yok Don National Park was established by Decree in 2002
(International Centre for Environmental Management (ICEM) 2003). Under
Vietnam's Law on Forest Protection and Development of 2004 (No. 25
2004), National Parks are considered special use forests, which are
used mainly for conservation of nature, preservation of national forest
ecosystems, and biological gene resources; scientific research;
protection of historical and cultural relics as well as landscapes; in
service of recreation and tourism. The Law on Forest Protection and
Development prohibits, among other things: (1) Unpermitted logging; (2)
unpermitted hunting, shooting, capture, caging, or slaughter of forest
animals; (3) illegally destroying forest resources or ecosystems; (4)
violating regulation on forest fire prevention; (5) violating
regulations on prevention and elimination of organisms harmful to
forests; (6) illegal encroachment; (7) illegal possession, transport,
or trade in forest plants and animals; (8) illegally grazing cattle in
strictly-protected zones of special use forests; (9) illegally exerting
adverse impacts on wildlife; and (10) illegally bringing toxic
chemicals or explosives into forests (Article 12). However, the Yok Don
National Park apparently lacks specific regulations governing
activities within the Park (Eames et al. 2004), and it is unclear what
tangible protections, if any, are afforded the species in this area.
Furthermore, there are continued external threats to the biological
resources in the park (e.g., the proposed Ea Tung dam) (ICEM 2003)
(Factor A) and hunting (Factor B). Eames et al. (2005) reported that
hunting was a problem for wildlife within the Yok Don National Park.
Thus, the measures in place are ineffective at reducing the threats to
this species.
Summary of Factor D
Existing regulatory mechanisms throughout the giant ibis' range are
ineffective at reducing or removing threats directed at the species,
including habitat modification (Factor A) and hunting (Factor B). We
believe that the inadequacy of regulatory mechanisms, especially with
regard to lack of law enforcement and habitat protection, is a
contributory risk factor for the giant ibis.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
Other factors which affect the giant ibis' continued existence are:
its small population size and environmental toxins.
Small population size: Small, isolated populations of wildlife
species are susceptible to demographic shifts and genetic problems
(Shaffer 1981). These threat factors, which may act in concert, include
natural variation in survival and reproductive success of individuals,
chance disequilibrium of sex ratios, changes in gene frequencies due to
genetic drift, and diminished genetic diversity and associated effects
due to inbreeding. Demographic problems may include reduced
reproductive success of individuals and chance disequilibrium of sex
ratios.
We are unaware of any genetic studies for the giant ibis. However,
threats to near- and long-term genetic viability can be estimated. In
the absence of more species-specific life history data, the 50/500 rule
(as explained under Factor E for the black stilt) (Soul[eacute] 1980;
Hunter 1996) may be used to approximate minimum viable population
sizes, as described under Factor E for the black stilt. The available
information indicates that the largest concentration of giant ibis
consists of 30 to 40 pairs (Clements et al. 2007). This would equate to
60 to 80 individuals, which just meets the minimum effective population
size (Ne = 50 individuals) required to avoid risks from
inbreeding. The current maximum estimate of no more than 250
individuals for the entire population (Clements et al. 2007) is only
half of the upper threshold (Ne = 500) required for long-
term fitness of a population that will not lose its genetic diversity
over time and that will maintain an enhanced capacity to adapt to
changing conditions. As such, we currently consider the species to be
at risk of long-term genetic viability and associated demographic
problems.
Environmental toxins: Environmental toxins likely pose a threat to
the giant ibis, given its foraging habit and diet. Agent Orange was one
of the primary defoliants sprayed during the Vietnam War (Westing
2002). One of the formulations (2,3,7,8-tetrachlorodibenzo-p-dioxin
(TCDD)) released dioxin as a byproduct as it broke down. Dioxin is a
known human carcinogen. Studies conducted following the war through the
mid-1990s found that residents of southern Vietnam contained extremely
high levels of dioxin found in fluid or tissue samples, including
mother's milk and food fish. Sediment studies in the 1980s indicated
that dioxin can move through soil into lakes or rivers, where it
attaches to organic material in the sediment. In 1995, tissue sample
studies revealed that even residents in areas that were not sprayed by
Agent Orange (in northern Vietnam) contained low levels of TCDD
contamination. In 2001, high levels of dioxin were still being detected
in residents in southern Vietnam 30 years after TCDD was sprayed.
Residents born subsequent to spraying and newly arrived residents had
similarly high levels of dioxin in their systems. The authors concluded
that it is highly probable that current dioxin contamination detected
in humans is the result of past and current exposure to dioxin that has
moved from the soil into river sediments, into fish,
[[Page 3166]]
and subsequently into people from fish consumption (Schechter et al.
2001). The giant ibis forages in mud flats, probing the mud with their
bills. With evidence that dioxin contamination in soils persists more
than 30 years after the Vietnam War, it is likely that the giant ibis
is being exposed to this contaminant.
According to Gatehouse (2004), when fish, birds, or mammals are
exposed from conception through postnatal or post hatching stages,
dioxins may disrupt development of several major organ systems
(including the endocrine, reproductive, immune and nervous systems).
Dioxins are potent developmental toxicants even at low concentrations,
and effects of dioxin poisoning in birds include poor breeding success,
embryo lethality, and developmental deformities (Gatehouse 2004).
Although we are unaware of any studies of the effect of environmental
contaminants on the giant ibis, this may be a factor in the species'
low fledging success (estimated to be 50 percent (Clements et al.
2007)).
Birds may be exposed to dioxins in their food or by foraging in
contaminated soil (Gatehouse 2004). Animals vary in their sensitivity
to dioxin (Karchner et al. 2006) and levels of contamination vary
relative to their trophic level (position in the food chain) (Gatehouse
2004). Giant ibis consumes primarily invertebrates, small reptiles, and
amphibians (http://www.rdb.or.id; BLI 2001b, 2007h; Davidson et al. 2002).
According to Gatehouse (2004), other bird species at this mid-trophic
level accumulate dioxin contamination at a low to midrange (where birds
of prey have the highest levels of contamination). Dioxin poisoning is
known to affect reptiles, resulting in development abnormalities
(Shirose et al. 1995). Residual contamination in the tissues of prey
species may remain long after contaminant concentrations are reduced
(Gatehouse 2004). Given that giant ibis is a mid-trophic level species,
which are known to accumulate dioxin at low-to mid-range levels, and
that reptiles, a food source for giant ibis, are known to retain
residual dioxin within their tissues, it is likely that the giant ibis
is being exposed to dioxin through its prey species as well.
Summary of Factor E
The giant ibis' small population, estimated to be at least 100
pairs, but no more than 250 total individuals, poses a risk to the
species throughout its range with regard to lack of near-term long-term
genetic viability and to potential demographic shifts. We consider the
species' extremely small population size and associated lack of genetic
viability and threats of demographic shifts to be significant risks to
the giant ibis throughout its range.
Dioxin contamination likely poses a threat to the giant ibis, given
its foraging habits of eating along mud flats and probing the mud with
its bill and the fact that dioxin contamination remains in the soil
more than 30 years later. Diet may also expose giant ibises to dioxin
accumulated in the tissue of prey species. Although we believe that
dioxin contamination could be a factor contributing to the decline of
the giant ibis, there has been no direct research into the effects of
dioxin on giant ibis. As such, insufficient information precludes our
ability to determine whether dioxin contamination endangers the
species.
Conclusion and Determination for the Giant ibis
We have carefully assessed the best available scientific and
commercial information regarding the past, present, and potential
future threats faced by the giant ibis. We have determined that the
species is in danger of extinction throughout all of its known range
primarily due to ongoing threats to its habitat (Factor A), unregulated
hunting (Factor B), and genetic and demographic risks associated with
the species' small population size and habitat fragmentation (Factor
E). Predation threatens the largest known concentration of giant ibis
in the Northern Plains of Cambodia (Factor C). Furthermore, we have
determined that the inadequacy of regulatory mechanisms to reduce or
remove these threats is a contributory factor to the risks that
endanger this species' continued existence (Factor D). Therefore, we
are determining endangered status for the giant ibis under the Act.
Because we find that the giant ibis is endangered throughout all of its
range, there is no reason to consider its status in any significant
portion of its range.
IV. Gurney's pitta (Pitta gurneyi)
Species Description
The Gurney's pitta is a member of the Pittidae family and is native
to Myanmar and Thailand. The species is also known commonly as the
black-breasted pitta (http://www.rdb.or.id; BLI 2001c) and the jewel-thrush
(BLI-IP & Biodiversity and Nature Conservation Association (BANCA)
Darwin Project Office 2004). Adults are between 7 and 8 in (18 and 20
cm) tall. The male has a blue crown and a turquoise-tinged tail. Black
plumage covers the breast, with brown on the upper side, and black and
yellow bands along the sides of the underbelly. The female has a brown
crown and paler light-brown and buff (or black and yellow) banding on
the underparts. The juvenile is draped in brown plumage on the crown,
nape, and breast, with pale streaks on the upper belly and white
speckles on the wings (BLI 2007g; Gould 1969; Thailand Scientific
Authority 1990).
Taxonomy
Gurney's pitta, in the family Pittidae, was described by Hume as
Pitta gurneyi in 1875 (BLI 2005) from a specimen obtained in Myanmar.
Habitat and Life History
This species' habitat requirements of this species were poorly
understood until surveys were conducted in the 1980s (see Population
Estimates, below). Gurney's pitta inhabits lowland, semi-evergreen
secondary rainforest, at elevations from 260 to 460 ft (80 to 140 m).
They are especially found at elevations less than 328 ft (100 m), in
areas with little to no undergrowth (BLI 2000b, 2001c; Gould 1969).
Access to permanent sources of water is a central feature of Gurney's
pitta habitat, such that populations are often located near gully
systems where moist conditions remain year-round (BLI 2000b, 2001c).
Gurney's pitta has been described as a ``relatively silent
species'' (Rose 2003, p. 142); although more audible during mating
season, and the species occurs more often in the mornings and evenings
(http://www.rdb.or.id; BLI 2001c; Gould 1969). The species rarely ventures
into open areas (http://www.rdb.or.id; BLI 2001c) and does not live in groups
(Thai Society for the Conservation of Wild Animals (TSCWA) no date
(n.d.)). A terrestrial bird, Gurney's pitta hops around the forest
floor on its strong hind legs to forage on insects, snails, and
especially earthworms (http://www.rdb.or.id; BLI 2001c; Kekule 2005; TSCWA
n.d.).
Apparently monogamous (http://www.rdb.or.id; BLI 2001c), the species
breeds during the monsoon season from April to October (http://www.rdb.or.id;
BLI 2001c, 2007g). Dome-shaped nests with a single opening are built
approximately 3.3 to 8.2 ft (1 to 2.5 m) off the ground in spiny
understory palms, including rakum (Salacca rumphii or Salacca
wallichiana), rattan (Daemonorops or Calamu longisetus), and licuala
palms (Licuala spp.) (BLI 2001c, 2003b; Kekule 2005; Rose 2003; TSCWA
n.d.). Eggs are cream-colored with brown flecks, the typical clutch
size is 3 to 4, and eggs are incubated by both males and females for as
few as 10 and up to 20 days
[[Page 3167]]
(http://www.rdb.or.id; BLI 2001c; Rose 2003; TSCWA n.d.). In captivity, pairs
nested twice in 1 year (http://www.rdb.or.id; BLI 2001c). Gurney's pitta
apparently has a low rate of breeding success, with an average
production of one (Lambert 1996 as cited in BLI 2001c), two, or, at
most, three chicks (Kekule 2005) fledged per clutch. In the only nest
monitoring study, three giant ibis nests achieved an overall fledging
rate of 27.3 percent (http://www.rdb.or.id; BLI 2001c; Rose 2003). Thus, the
species has low fledging success.
Historical Range and Distribution
Gurney's pitta is native to Myanmar and Thailand, and the species
was historically observed throughout the Thai-Malay peninsula
(peninsular Thailand and adjacent southern Myanmar) (http://www.rdb.or.id; BLI
2001c, 2007g). The species has been characterized as formerly common
across much of this range (BLI 2000b; Kekule 2005). However, BirdLife
International (2001c) pointed out that the Gurney's pitta will not be
found in absence of its preferred habitat and characterized the species
as locally abundant within its preferred habitat (lowland, semi-
evergreen secondary rainforest in areas with little-to-no undergrowth)
(BLI 2000b, 2001c; Gould 1969).
A comparison of the confirmed observations of Gurney's pitta
maintained by BirdLife International (2001c) since the species was
first described reveals that there have often been large gaps in
observations in the past. In Myanmar, the species was not observed for
the nearly 30-year period between 1877 and 1904, and went unobserved
again in Myanmar between 1914 and 2003. In Thailand, the species was
historically observed with greater frequency (http://www.rdb.or.id; BLI
2001c). However, there were long periods during which the species was
not observed in Thailand, including a 50-year period, from 1936 to
1986, during which there was only one confirmed observation of the
species in 1952. Gould noted in 1969 that the species ``moves about
quite a lot'' (Gould 1969, p. 154), which may be a reference to the
species' ``disappearance'' and ``reappearance'' across its range (see
also Population Estimates, below).
These occurrence records are likely incomplete for several reasons
other than the species' rarity, including: (1) The relative silence of
the species, making it difficult to detect when surveying suitable
habitat (for instance, Rose (2003) noted that during a 39-hour period
observing one nest, only nine calls were heard); (2) long periods of
war within the region (Kekule 2005) (for instance, Thailand was
involved in or affected by war from 1965-1988); (3) the inaccessible
habitat and danger from landmines (in Myanmar, for example (Kekule
2005)); and (4) government regulations restricting access to
researchers (Kekule 2005, regarding Myanmar). For these reasons,
experts caution against claims of extinction until thorough surveys
have been completed (Butchart et al., 2006).
The distribution of Gurney's pitta appears to have steadily
contracted in a southerly direction (BLI 2001c). Prior to 1950, the
species was observed in several locations within Myanmar's Tanintharyi
Division (referred to historically as ``Tenasserim'') and in the
central (Prachuap Khiri Khan) and southern (Chumphon, Ranong,
Nakhonsrithammarat, Phuket, Phatthatumg, and Trang) Provinces of
Thailand. Between 1950 and 1979, the species was only observed once, in
the southernmost Province of Thailand's central region, Prachuap Khiri
Khan. Between 1980 and 2000, the species was observed only in southern
peninsular Thailand (in Phangnga, Krabi, and Suratthani Provinces)
(http://www.rdb.or.id; BLI 2001c). Until its rediscovery in Myanmar in 2003,
the species was believed to have a range limited to a 20 mi2
(50 km2) area in Thailand (BLI 2000b). Experts believe that
steady habitat loss since the 1920s has been a main driver in the
species' historical decline (BLI 2000b, 2001c; Rose 2003).
Current Range and Distribution
BirdLife International (2000b) estimated the range of Gurney's
pitta to be 942 mi\2\ (2,440 km\2\ ). However, range estimates are
based on the ``Extent of Occurrence'' for the species, which is defined
by the authors as ``the area contained within the shortest continuous
imaginary boundary which can be drawn to encompass all the known,
inferred, or projected sites of present occurrence of a species,
excluding cases of vagrancy'' (BLI 2000b, p. 22). Therefore, this
estimate likely includes areas that are unsuitable for the pitta, such
that its range is probably smaller than this estimate.
Today, the Gurney's pitta is found in two areas, one within each
range country. Details for each range country will be discussed below,
starting with Thailand, because much of what we know about the Gurney's
pitta is based on this population.
Thailand: In Thailand, Gurney's pitta was rediscovered in 1986 in
at least five localities within its historical range, including
Prachuap Khiri Khan, Suratthani, Phangnga, Krabi, and Trang Provinces.
Although two territories may still exist in Trang Province (in an area
called Tambon Aw Tong) (Rose 2003), the only remaining viable
population occupies a 2-mi\2\ (5.2-km\2\) area in Krabi Province, near
Mount Khao Nur Chuchi (BLI 2007g; Round & Gretton 1989). Its range is
described as extremely small and declining (Rose 2003).
The Mt. Khao Nur Chuchi area may be referred to by any of several
names, including Khao Nur Chuchi Reserve, Khlong Pra-Bang Khram Non-
Hunting Area, Khlong Pra-Bang Khram Wildlife Sanctuary (Rose 2003,
Kekule 2005), and Kao Phra Bang Khram Forest Reserve, which describes
an area adjacent to the wildlife sanctuary (http://www.rdb.or.id; BLI 2001c;
TSCWA n.d.). Following the rediscovery of Gurney's pitta near Mt. Khao
Nor Chuchi in 1986, a non-hunting area was established in 1987. This
area was upgraded to a wildlife sanctuary in 1993; however, crucial
areas of pitta habitat were not included in the sanctuary
(http://www.rdb.or.id; BLI 2001c; Round 1999). Rather, the remaining
territories remain part of the Kao Phra Bang Khram Forest Reserve (see
Factors A and D). Hereafter, this population will be referred to as the
Khao Nur Chuchi population.
Myanmar: In Myanmar, Gurney's pitta was rediscovered in 2003 at
four sites in the Ngawun Reserve Forest, within its historic range of
Tanintharyi Division, in southern Myanmar. All sightings were within
1.2 mi (2 km) of the trans-Tanintharyi highway and within the 193 mi\2\
(500 km\2\) Ngawun Forest Reserve (BLI-IP & BANCA Darwin Project Office
2004). The species also apparently occurs in neighboring Lenya forest,
site of the proposed Lenya National Park, also in Tanintharyi Division
(BLI-IP & BANCA Darwin Project Office 2006).
Researchers believe that Myanmar has the largest remaining suitable
habitat for the species (BLI-IP & BANCA Darwin Project Office 2004;
Eames et al. 2005). In 2004, using satellite imagery, the remaining
habitat available to the pitta was estimated to be 1,349 mi\2\ (3,496
km\2\). Most of this habitat is fragmented, but the five largest
patches total an area of 553 mi\2\ (1,431 km\2\) and range in size from
53 to 180 mi\2\ (137 to 467 km\2\) (BLI-IP & BANCA Darwin Project
Office 2004), significantly larger than the entire estimated range of
the Gurney's pitta (of 20 mi\2\ (50 km\2\)) prior to its rediscovery in
Myanmar (Eames et al. 2005). As of 2005, experts also believed that
suitable habitat existed in a neighboring Lenya forest to support
Gurney's pitta (BLI-IP & BANCA Darwin Project Office 2006; Eames et al.
2005).
[[Page 3168]]
Population Estimates
Population estimates are provided for the global population of
Gurney's pitta, as well as for each range country. Thailand is
discussed before Myanmar, as most information on Gurney's pitta is
based on the population in Thailand, which was the only known
population of Gurney's pitta until 2003 when it was rediscovered in
Myanmar.
Global population estimate: The relative silence of this species
has made it difficult to census (David Olson, Irvine Ranch Land Reserve
Trust, in litt. February 2007; Rose 2003). Until the recent rediscovery
of Gurney's pitta in Myanmar in 2003 (BLI 2003b), the global population
estimate for Gurney's pitta was based solely on the Thai population,
which stood between 24 and 30 individuals (http://www.rdb.or.id; BLI 2001c;
Rose 2003). With the discovery of the Myanmar population, the global
population may be between 175 to 185 individuals. The IUCN has not
undertaken a formal re-evaluation of the global population of Gurney's
pitta since its rediscovery in Myanmar.
Thailand: The Khao Nur Chuchi population is considered the last
remaining viable population in Thailand (Round & Gretton 1989).
Censuses undertaken following its rediscovery in the late 1980s aimed
to identify additional localities and the number of individuals extant
within the area. The species reportedly declined from 44 to 45 pairs in
1986 (BLI 2000b) to 17 pairs in 1987 (Rose 2003) and to 9 pairs in 1997
(BLI 2000b) and then increased to 11 breeding pairs in 2000
(http://www.rdb.or.id; BLI 2001c). As of 2003, the population stood between 24
and 30 individuals (http://www.rdb.or.id; BLI 2001c; Rose 2003).
Myanmar: BirdLife International--Indochina Program has been
conducting site surveys on the rediscovered populations within the
Ngawun Forest Reserve (BLI 2003b). In 2003, at least 10 to 12 pairs
were observed (BLI 2003b; Eames et al. 2005). In 2004, researchers
determined that the Myanmar population was sizable, having made
approximately 150 pitta sightings (BLI-IP & BANCA Darwin Project Office
2004).
Extrapolating on the availability of suitable habitat, researchers
estimated that the Myanmar population might include up to 8,000 pairs
(Eames et al. 2005; Grimmitt 2006). However, we believe that this
population estimate, based on the availability of suitable habitat, may
be an overestimate for this species for two reasons: (1) The Myanmar
population may not be randomly distributed in suitable habitat as
assumed by these researchers, and (2) the extrapolation does not take
into account human-induced threats, such as trapping. Therefore, until
the predictions have been ground-truthed, we are unable to consider the
8,000 pair estimate as a reliable reflection of the current population
size. We consider the 150 pitta sightings made in 2004 to be the most
accurate current estimate of the Gurney's pitta population size in
Myanmar.
Conservation Status
The conservation status of the Gurney's pitta is provided both on a
global level and according to individual range countries. Thailand is
again discussed before Myanmar.
Global population status: The Gurney's pitta has been classified as
``Critically Endangered'' by the IUCN since 1994 (BLI 2005).
Thailand: Gurney's pitta is protected by the Wildlife Animal
Reservation and Protection Act (WARPA) in Thailand (B.E. 2535 1992;
Eames et al. 2005). However, this regulatory mechanism is ineffective
at reducing or removing threats directed at the species (see Factor D).
Myanmar: The species is protected in Myanmar by the Wildlife Act of
1994 (http://www.rdb.or.id; BLI 2001c). However, this regulatory mechanism is
ineffective at reducing or removing threats directed at the species
(see Factor D).
Summary of Factors Affecting the Gurney's pitta
Where applicable in the sections below, factors affecting the
survival of Gurney's pitta are discussed in two parts: (1) Regional
factors (affecting or including both range countries), and (2) Factors
within individual range countries.
A. The Present or Threatened Destruction, Modification, or Curtailment
of the Gurney's Pitta's Habitat or Range
(1) Regional factors
Experts believe that steady habitat loss since the 1920s
contributed to the species' historical decline (BLI 2000b, 2001c; Rose
2003). Large-scale conversion of habitat for agriculture (such as rice
planting) in Southeast Asia, including Thailand and Myanmar, began in
the 1800s. This was followed by forest clearing for cash crops, such as
rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis). The 1950s
saw the advent of a commercial logging industry to satisfy an
increasing demand for Asian timber (Sodhi et al. 2004). Despite a
complete logging ban implemented in Thailand in 1989, illegal logging
and forest conversion for agriculture continued.
(2) Factors Within Individual Range Countries
Thailand: Thailand has lost an average of 1,274 mi\2\ (3,300 km\2\)
of natural forest since 1960, with deforestation rates in the last
three decades often exceeding 3 percent per year (Brown et al. 2001).
By 1987, only 20 to 50 km\2\ of forest below 328 ft (100 m) (habitat
preferred by Gurney's pitta) remained in peninsular Thailand (BLI
2000b, 2001c). A portion of the last remaining viable population of
Gurney's pitta, the Khao Nur Chuchi population, was included within the
Khlong Pra-Bang Khram Wildlife Sanctuary in 1993. However, encroachment
for settlements and clearing for crops were continuous problems through
the 1990s, as summarized by BirdLife International (2001c). The other,
more extensive, portion of the population was included in the Kao Phra
Bang Khram Forest Reserve (http://www.rdb.or.id; BLI 2001c).
There has been a substantial conservation effort to foster
sustainable agricultural practices around the Khao Nor Chuchi protected
area. In 1990, the Khao Nor Chuchi Lowland Forest Project was
established to engage the local community in management, education
programs, and ecotourism, to reduce pressure on the remaining forest
habitat. This project met with only limited success (BLI 2007g), and
illegal forest clearance has persisted into the 21st century
(http://www.rdb.or.id; BLI 2001c; Rose 2003). Moreover, the more recent
practice of planting oil palms, which are more profitable than rubber
plantations, on illegally cleared forest patches, removes the natural
ground cover used for foraging and concealment by the ground-dwelling
pitta (Rose 2003).
Myanmar: Gurney's pitta is found within the 193 mi \2\ (500 km \2\
) Ngawun Reserve Forest, described as the largest remaining contiguous
lowland forest in southern Myanmar (BLI 2003b, 2005), and also within
neighboring Lenya forest, site of a proposed National Park (BLI-IP &
BANCA Darwin Project Office 2006), located within Tanintharyi Division.
Recent surveys indicated that Myanmar's Tanintharyi Division contains
substantial suitable habitat for pittas (estimated to be 1,349 mi \2\
(3494 km \2\ ), but much of it was fragmented (BLI 2005) and
deforestation for oil palm plantations was ongoing (Eames et al. 2005).
Between 1990 and 1995, Myanmar lost 1,494 mi \2\ (3,870 km \2\ ) of
forest per year, averaging a 1.4 percent reduction in forests per year
(FAO 1999). In southern Tanintharyi Division,
[[Page 3169]]
logging reduced one large patch of lowland forest from 163 mi \2\ (423
km \2\ ) in 1990 to 102 mi \2\ (265 km \2\ ) in 2000 (Eames et al.
2005).
Summary of Factor A
Although the known range of the Gurney's pitta has expanded
considerably with the rediscovery of the species in Myanmar, habitat
conversion, destruction, and encroachment continues to be a significant
factor throughout the species' range. Illegal logging and conversion
for cash crops continue throughout the species' range. Based on the
above information, we find that the Gurney's pitta is at significant
risk throughout its range due to the present or threatened destruction,
modification, or curtailment of its habitat or range.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Gurney's pitta was popular in the pet trade in the 1980s and was
overutilized for this purpose by local snare-trappers (BLI 2007g; Rose
2003; Thailand Scientific Authority 1990). Illegal trade in the species
was occurring even when experts were not reporting sightings of the
species. For instance, the species was reportedly on the price list of
an illicit Thai-based animal dealer in 1985, one year before the
population was rediscovered in Thailand (Thailand Scientific Authority
1990). Ironically, the rediscovery of the pitta in Thailand can be
credited to a wildlife smuggler in Bangkok, who helped rediscover the
species. After the smuggler was found with a bird in his possession, he
led researchers to a small forest patch in southern Thailand, where the
species was subsequently observed (Round & Gretton 1989). The species
was listed in Appendix III of CITES by Thailand in 1987 (UNEP-WCMC
2007a), requiring that a certificate of origin or export permit from
Thailand accompany international exports of the species. In 1990,
Gurney's pitta was uplisted to CITES Appendix I, which prohibited
international trade for commercial purposes. According to the WCMC
database, there has been no CITES-reported trade in this species since
its listing in 1987 (UNEP-WCMC 2007b).
Trapping for the caged-bird trade continued to threaten the species
through the late 20th into the early 21st century (http://www.rdb.or.id; BLI
2001c; Rose 2003), including evidence of non-specific poaching at Khao
Nur Chuchi Non-Hunting Area (WorldTwitch Thailand 2000). Although Rose
(2003) believed that trapping had ceased, Kekule (2005) found bird-nets
surrounding an abandoned pitta nest within the Khao Nur Chuchi
population in Thailand; the nets were placed there by villagers to
capture the birds (see also Factor D).
We are not aware of any specific information regarding trapping or
illegal trade in Myanmar, and there is no specific information
indicating that scientific or educational uses of the species are a
threat.
Summary of Factor B
Trapping has impacted the species in the past and may be ongoing.
Given the species' small population size in Thailand, estimated at 24
to 30 individuals, reports of ongoing trapping and hunting activities
within the species' only known range in Thailand is a significant
concern. As such, we consider the trapping or hunting to be factors
that threaten the species in Thailand.
C. Disease or Predation
There is no information about diseases affecting Gurney's pitta.
Regarding predation, dog-tooth cat snake (Boiga cynodon) is a natural
predator of the Gurney's pitta. The dog-tooth cat snake is a member of
the night tree adder family that can reach lengths up to 9 ft (2.75 m).
A tree dweller, this snake is native to several southeast Asian
countries. In Thailand, the snake has been found in Prachuap Khiri Khan
(the location of the largest known pitta population in Thailand) and it
shares many similarities with Gurney's pitta, including living mainly
in lowland rain forests, rarely entering cultivated areas or human
settlements, and principally feeding on birds and their eggs (Thiesen
n.d). Gretton (1988) reported that a dog-tooth cat snake killed near a
Gurney's pitta nest contained a chick that it had apparently taken from
the nest the previous day. Given the small remaining population size in
Thailand (estimated to be 11 breeding pairs in 2000 (BLI 2000b)),
predation by the dog-tooth cat snake would present a threat to the
pitta, but no further information on this threat is available to us.
Summary of Factor C
Predation may affect Gurney's pittas, but there is insufficient
information for us to consider this a significant factor currently
impacting the Gurney's pitta.
D. The Inadequacy of Existing Regulatory Mechanisms
Thailand: Gurney's pitta is protected by the Wildlife Animal
Reservation and Protection Act (WARPA) (B.E. 2535 1992; Eames et al.
2005). Under this act, hunting is prohibited (section 16), as is
possession of carcasses (section 19), trade (section 20), and
collection, harm, or possession of nests (section 21). Violations of
sections 16, 19, or 20 may result in imprisonment not exceeding four
years or fines not exceeding 40,000 baht, or both. Violations of
section 21 may result in imprisonment not exceeding 1 year or fines not
exceeding 6,000 baht. However, while Thai law does not allow capture or
sale of the Gurney's pitta, the law does allow for possession of the
species and bird-nets have recently been found near empty Gurney's
pitta nests within the range of Thailand's only remaining viable
population of the species (the Khao Nur Chuchi population) (Kekule
2005). This suggests that this regulation is inadequate to protect the
few remaining individuals of this species from hunting (Factor B).
Protection of the species' habitat has not been effective in
addressing forest clearance and poaching (Factor A). When the Khlong
Pra-Bang Khram Wildlife Sanctuary was established in 1993, it provided
incomplete protection for pitta territories, as only 5 of the 21 known
pitta territories were encompassed within the Sanctuary. The most
important and extensive areas of pitta habitat and territories were not
included, including a crucial 12 mi\2\ (30 km\2\) area considered to be
core to the pitta habitat (Round 1999; BLI 2001c). Sanctuaries are
reportedly rarely patrolled by staff (WorldTwitch Thailand 2000) and a
survey in 2001 confirmed that protection and law enforcement at Khao
Nor Chuchi was essentially nonexistent (Rose 2003). While the Sanctuary
receives funds for its management from the central government,
authority to address problems within the Reserve is given to the
provincial officials. This provides neither the authority nor the
responsibility for Reserve staff to focus on problems within the
reserve (BLI 2001c). As habitat destruction is ongoing within giant
ibis habitat (BLI 2001c; Kekule 2005; Rose 2003), this regulatory
mechanism is ineffective at addressing the threat of habitat
destruction (Factor A).
Myanmar: This species is considered a ``completely protected''
species of wildlife under section 15(a) of Myanmar's Protection of
Wildlife and Wild Plants and Conservation of Natural Areas Law of 1994
(Forest Department Notification No. 583/94; Protection of Wild Life and
Wild Plants and Conservation of Natural Areas Law 1994). This law made
it is illegal to kill, hunt, wound, possess, sell, transport, or
transfer a completely protected species without permission (section
37).
[[Page 3170]]
Violators of this law are subject to imprisonment for up to 7 years or
a fine up to kyats 50,000, or both (section 37). We have no information
that the species is being trapped, hunted, or sold in Myanmar.
Therefore, this regulation is not currently removing or reducing the
primary threat to this species within Myanmar, habitat destruction
(Factor A).
There are currently no protected areas in the peninsular region
where the Gurney's pitta is found (Hirschfeld 2008). Within the Ngawun
Forest Reserve, the habitat of the Gurney's pitta is protected under
the provisions of the Burma Forest Act of 1902, as amended
(Conservation Monitoring Centre 1992). Prohibited activities in
reserved forests include trespassing, pasturing, damaging trees,
setting fires, mining, cultivation, poisoning or dynamiting, hunting,
shooting, fishing, or setting traps or snares. According to BirdLife
International--Indochina Program (BLI-IP & BANCA Darwin Project Office
2005), the Ngawun Forest Reserve is the largest block of lowland forest
in southern Myanmar, but it remains inadequately protected due to
ineffective enforcement. Therefore, this regulation is not removing or
reducing the primary threat to this species within Myanmar, habitat
destruction (Factor A).
The species is also apparently extant in neighboring Lenya forest,
site of the proposed Lenya National Park (BLI-IP & BANCA Darwin Project
Office 2006). However, it appears that the Park has yet to be
established and, as currently drawn, its boundaries would not encompass
critical pitta territories within the Lenya Forest or the Ngawun Forest
Reserve (BLI-IP & BANCA Darwin Project Office 2006; Grimmitt 2006).
Therefore, because that establishment of the Park as currently drawn
would exclude pitta territory, this mechanism would not likely remove
or reduce the primary threat to this species within Myanmar, habitat
destruction (Factor A).
Summary of Factor D
Although regulatory mechanisms are in place that could reduce or
remove threats to the species, implementation of these mechanisms
appears to be slow (such as the delay in establishing the proposed
National Park), ineffective (such as the inability to quell poaching
threats to the species), or inadequate. For instance, in Thailand,
there is evidence of trapping within Gurney's pitta territory. Despite
indications that poaching is ongoing, the law allows for possession of
the species, although it does not allow capture or sale. Therefore, we
believe the inadequacy and ineffective implementation of regulatory
mechanisms are contributory risk factors that endanger the Gurney's
pitta.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
Collection of forest products may constitute a disturbance to
Gurney's pitta in Thailand during their breeding season. The edible
fruits of the rakum palm, one of the palms in which the Gurney's pitta
nests, are sought after in Thailand (BLI 2007g). Peak harvest occurs in
June and July (World Agroforestry Center (WAC) n.d.), coinciding with
the Gurney's pitta breeding season (http://www.rdb.or.id; BLI 2001c, 2007g).
However, forest-collected fruit is considered inferior to the
cultivated variety, harvest has never been tracked (WAC n.d.), and we
are unaware of any research concerning this type of disturbance in
relation to the Gurney's pitta. Thus, we are unable to conclude that
this activity threatens the species' survival, due to insufficient
information.
Small, isolated populations of wildlife species are susceptible to
demographic and genetic problems (Shaffer 1981). These threat factors,
which may act in concert, include natural variation in survival and
reproductive success of individuals, chance disequilibrium of sex
ratios, changes in gene frequencies due to genetic drift, and
diminished genetic diversity and associated effects due to inbreeding.
Demographic problems may include reduced reproductive success of
individuals and chance disequilibrium of sex ratios (Charlesworth &
Charlesworth 1987; Shaffer 1981). Using the 50 / 500 rule (as described
under Factor E for the black stilt) (Soul[eacute] 1980; Hunter 1996)
and given the two population estimates (24 to 30 in Thailand
(http://www.rdb.or.id; BLI 2001c; Rose 2003), and 150 in Myanmar (BLI-IP &
BANCA Darwin Project Office 2005)), the population in Thailand has
likely undergone inbreeding. In addition, both the Thai and the Myanmar
populations exist at numbers well below the minimum (of at least 500
individuals in order to prevent the loss of genetic diversity over time
and maintain an enhanced capacity to adapt to changing conditions. As
such, we currently consider the species to be at significant risk due
to lack of near- and long-term genetic viability.
Summary of Factor E
The Gurney's pitta may be adversely affected by collection of the
rakum fruit in Thailand, which grows in a tree in which the pitta nests
and which ripens coincident with the Gurney's pitta's breeding season.
However, no specific data exist to indicate that disturbance from fruit
collection may be an actual threat. Therefore, we do not consider fruit
collection to be a factor impacting the Gurney's pitta at this time.
The small population size of the Gurney's pitta, estimated at 24 to
30 in Thailand and 150 in Myanmar, poses a risk to this species
throughout its range with regard to lack of near-term long-term genetic
viability and to potential demographic shifts. Therefore, we consider
the species' extremely small population size and associated genetic and
demographic risks to be significant factors that endanger the Gurney's
pitta throughout its range.
Conclusion and Determination for the Gurney's Pitta
We have carefully assessed the best available scientific and
commercial information regarding the past, present, and potential
future threats faced by the Gurney's pitta. We have determined that the
species is in danger of extinction throughout all of its known range
primarily due to habitat loss (Factor A), trapping, or hunting in
Thailand (Factor B), and genetic and demographic risks associated with
the species' small population size (Factor E). Furthermore, we have
determined that the inadequacy of existing regulatory mechanisms to
reduce or remove these threats is a contributory factor to the risks
that endanger this species' continued existence (Factor D). Therefore,
we are determining endangered status for the species under the Act.
Because we find that the Gurney's pitta is endangered throughout all of
its range, there is no reason to consider its status in any significant
portion of its range.
V. Long-Legged Thicketbird (Trichocichla rufa)
Species Description
The long-legged thicketbird is an Old World warbler belonging to
the Sylvidae family, and native to the Fiji Islands. The species is
also commonly known as the long-legged warbler (BLI 2007i). Local
residents named the secretive thicketbird ``Manu Kalou,'' or ``Spirit
Bird,'' during the 19th century because of its ethereal voice (BLI
2000c; Dutson & Masibalavu 2004). Adults stand 6 in (17 cm) tall, with
long blue legs, a short black bill, and a long tail. Upperparts of the
body are warm brown with a long supercilium (head plumage). The throat
is white and the flanks are a pale, rufous color (BLI 2007i).
[[Page 3171]]
Taxonomy
The long-legged thicketbird was described by Reichenow as
Trichocichla rufa in 1890, and placed in the Sylvidae family as a
monospecific genus. Two specimens discovered on the island of Vanua
Levu in 1974 were described as a distinct subspecies (Trichocichla rufa
clunei) (BLI 2003c; Kirby 2003b; Helen Pippard, Director of
Environment, Suva, Fiji, in litt. February 2007). However, ITIS and
BirdLife recognize the long-legged thicketbird only to the species
level, and we accept this taxonomy.
Habitat and Life History
The long-legged thicketbird requires intact mid- to high-elevation
forest associated with riverine habitat and dense vegetation (H.
Pippard in litt. February 2007). Its habitat is dominated by old-growth
montane forest (BLI 2007i), and the species is found at altitudes
ranging from 2,625 to 3,281 ft (800 to 1000 m) (Dutson & Masibalavu
2004).
Because this species was known only from four voucher specimens
until 2002, very little is known about its life history (BLI 2007i). It
is characterized as a secretive ground-warbler that is easily
overlooked unless it is singing (BLI 2007i). Its call is distinctive,
and recognizing its song is considered key to identifying it in the
wild (Dutson & Masibalavu 2004).
Historical Range and Distribution
The long-legged thicketbird is endemic to the Fijian Islands. The
Fijian Archipelago comprises over 320 islands, over an area
approximating 502,000 mi\2\ (1.3 million km\2\) (Chand 2002).
Historically the species was found on two Fijian islands: Viti Levu and
Vanua Levu. Viti Levu, meaning ``Big Fiji,'' is the largest island,
with an area of 4,011 mi\2\ (10,390 km\2\). Vanua Levu, meaning ``Big
Land,'' is little more than half as large at 2,135 mi\2\ (5,530 km\2\)
(Chand 2002).
The long-legged thicketbird was long considered extinct, with no
confirmed observations since 1894 (BLI 2003c; Kirby 2003b) and several
unconfirmed sightings in 1967, 1973, and 1991 (BLI 2000c). The first
confirmed sighting in recent time was that of two individuals in 1974,
found on the island of Vanua Levu (BLI 2003c; Kirby 2003b). There was
no evidence of its continued existence until 2002, when it was
rediscovered on Viti Levu (BLI 2003c). The Fijian government considers
the species to be extinct on Vanua Levu, where forests are less intact
and there have been greater impacts from forest loss, including
invasive species (H. Pippard in litt. February 2007).
Current Range and Distribution
The long-legged thicketbird was rediscovered in 2002, although
confirmation of the sighting took nearly a year (BLI 2003c; Kirby
2003b). It was located at several sites on Viti Levu, found only in
dense undergrowth of the Fijian mountains (BLI 2003c; Kirby 2003b; H.
Pippard in litt. February 2007). However, a researcher who spent 5
years working in Fiji on conservation projects indicated that the
species is ``commonly found if you know where to look for it in mid-
elevation rocky streams with dense overstories'' (D. Olson in litt.
February 2007). The largest known concentration of the long-legged
thicketbird is found within the approximately 2 mi\2\ (5 km\2\) area
known as the Wabu National Forest Reserve (BLI 2007i). Little is known
about the species' current range, necessitating additional surveys in
suitable habitat (BLI 2007i).
Population Estimates
There is insufficient information to determine the historic
population levels of this species (BLI 2007i). Today, researchers
believe that the species is locally common in ideal habitat (unlogged
forest at elevations between 2,625 and 3,281 ft (800 and 1000 m)), but
that it is patchy in distribution and absent from most forest (BLI
2003c, 2007i; D. Olson in litt. February 2007; Kirby 2003b). The
current population is estimated to be between 50 to 249 individuals.
However, this estimation is a categorical one, used by BirdLife
International to conform to the IUCN criteria. The actual number of
individuals may be much smaller (or larger) than this range suggests.
In surveys conducted from 2002 to 2005, 12 pairs were discovered in
Wabu (BLI 2003c, 2007i; Kirby 2003b). Nine pairs were found along a
1.24-mi (2-km) length of stream in dense undergrowth thickets; two of
these pairs were accompanied by recently fledged juveniles. Using the
data from the 2005 field surveys, only 30 individuals were observed
during field surveys in 2005 (BLI 2003c; Kirby 2003b).
Conservation Status
The Fiji Department of Environment considers the extant long-legged
thicketbird on Viti Levu to be vulnerable to further decline or
extinction. Conservation priorities for this species include:
protection of forest and research on the species' habitat requirements
and impacts of invasive species on the species (H. Pippard in litt.
February 2007). As of 2007, the species was classified by the IUCN as
endangered, where it was previously classified as data deficient (BLI
2006b, 2007i; H. Pippard in litt. February 2007).
Summary of Factors Affecting the Long-Legged Thicketbird
A. The Present or Threatened Destruction, Modification, or Curtailment
of the Long-Legged Thicketbird's Habitat or Range
Habitat destruction from logging, conversion to agriculture, and
invasive species threatens the long-legged thicketbird habitat. The
most recent estimates of forest cover on the islands of Vanua Levu and
Viti Levu are from 1995. In 1995, the total forested area, including
mangrove forest, pine plantation, hardwood plantation, scattered
natural forest, medium dense natural forest, and dense natural forest,
on the Fiji Islands was 3,293 mi\2\ (9933 km\2\) (Lal & Touvou 2003).
This equated to just under half of Fiji's total land area and included
an excess of 490 mi\2\ (1,270 km\2\) of the dense forest, preferred by
the long-legged thicketbird (on Viti Levu, and 463 mi\2\ (1,200 km\2\)
on Vanua Levu) (Chand 2002). Although there is more forested area on
Vanua Levu than on Viti Levu, Fiji considers that the degree of habitat
degradation on Vanua Levu has resulted in the species' extirpation from
that island (H. Pippard in litt. February 2007).
Logging: According to the Fijian government, logging of virgin
forests is the primary threat to this species, which prefers intact
forest habitat (H. Pippard in litt. February 2007). Eighty-three
percent of the total land area, including most of the natural forest
cover, is privately owned (McKenzie et al. 2005). The forestry sector
contributes 2.5 percent to Fiji's gross domestic product (GDP) and
about F$50 million (US$27.6 million) in foreign exchange export
earnings annually (McKenzie et al. 2005).
The Fijian government began large-scale planting of pine and
hardwoods in the 1960s, such that today 13 percent of Fiji's forests
are planted. In 2003, there were approximately 204 mi\2\ (529 km\2\) of
hardwood plantations, mainly big-leaf mahogany (Swietenia macrophylla),
and 179 mi\2\ (463 km\2\) of pine (Pinus caribea) plantations (ITTO
2005). Habitat conversion for timber plantations, including pine and
big-leaf mahogany, in long-legged thicketbird habitat renders the
habitat unsuitable for the bird (BLI 2003c), as it prefers intact
forest (Pippard in litt. February 2007). See also Factor D.
Conversion to agriculture: The economy is dominated by the sugar
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industry and food crops, including taro, cassava, sweet potatoes or
kumala, and a wide variety of fruits and vegetables. An estimated 67
percent of the labor force is employed in agriculture, and this sector
of the economy accounts for almost 21 percent of Fiji's GDP (Chand
2002). In 2007, Fiji released census data that estimated the population
on the islands to be 827,900 inhabitants. This represents an increase
of 53,000 people since the 1996 census (Fiji Government Online 2007).
Most of these people inhabit the two main islands of Viti Levu and
Vanua Levu (Dutson & Masibalavu 2004). As the population increases, the
production area of these and other major food crops continues to
increase each year. In Fiji, all preferred arable lands are fully
utilized or unavailable for land tenure reasons. Thus, agriculture has
expanded onto steeper marginal land to the interior of the island
(Chand 2002). Agricultural conversion produces unsuitable conditions
for the long-legged thicketbird, which prefers intact forests with
dense vegetation, and the continuing expansion of agriculture into
steeper lands to the interior jeopardizes the long-legged thicketbird,
which prefers mid- to high-elevation forest (H. Pippard in litt.
February 2007).
Invasive species: Although BirdLife International (2007i) noted
that the influx of invasive species has not been shown to have
deleterious effects on the suitability of the habitat for the long-
legged thicketbird, it is unclear what factors were considered to
arrive at this determination, including whether they referred to
invasive animals or plants. The long-legged thicketbird prefers intact
forest, and the Fijian government considers invasive species to be a
factor that contributed to the species' extirpation from Vanua Levu (H.
Pippard in litt. February 2007). Invasive plants and animals are
problematic on Viti Levu (See Factor C for further discussion on
invasive animals). African tulip tree (Spathodea campanulata) is
invasive in forests and open areas of Viti Levu (McKenzie et al. 2005).
No longer facing the natural enemies or competition from other
species that they faced in their place of origin, invasive plants are
capable of spreading and outcompeting native species. Invasive plants
can spread and reproduce prolifically, causing significant changes to
ecosystems and upsetting their ecological balance.
Human disturbance, such as logging activities and agricultural
conversion, is considered a major vector for introducing invasive
plants. Once an invasive plant is introduced to an area, it has the
potential to invade larger areas (USGS 2006). Thus, in the face of
increasing habitat disturbance, invasive plants could pose a threat to
the long-legged thicketbird, which prefers intact primary forest (H.
Pippard in litt. February 2007). However, we are unaware of specific
information regarding the effect of invasive plants on the long-legged
thicketbird or its habitat. As, such we are unable to make a
determination as to the threat this factor might cause, if any, to the
species.
Summary of Factor A
Habitat destruction from logging and habitat conversion to
agricultural purposes produce unsuitable conditions for the long-legged
thicketbird, which prefers intact forest with dense vegetation. We
consider habitat destruction to be a significant threat to the long-
legged thicketbird that endangers the species throughout its range.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
According to the Fijian government, there is no trade, collection,
or captive breeding of the long-legged thicketbird at this time, nor is
any likely in the future (H. Pippard in litt. February 2007). There is
no known threat to the species from use for commercial, recreational,
scientific, or educational purposes. The species has not been formally
considered for listing in the Appendices of CITES (http://www.cites.org).
C. Disease or Predation
We have no information to indicate that the long-legged thicketbird
is threatened by disease.
Predation by invasive animals, namely rats (Rattus spp.) and
mongooses (Rallus phillopensis), is considered by Fiji to be a highly
significant threat to the species (H. Pippard in litt. February 2007).
Mongooses were introduced in 1883 to Fiji to kill rats, but both these
species could potentially be serious predatory threats to the long-
legged thicketbird (BLI 2000c). According to BirdLife International
(2007i), however, the long-legged thicketbird has been found
successfully nesting alongside these predators in Wabu, indicating that
mongooses may not be predators after all. The first sighting of this
species in 2002 was of a long-legged thicketbird warding off a mongoose
from its nearby nest, which would indicate that the species exhibits
anti-predatory behavior (Dutson & Masibalavu 2004). Given the species'
small population size, between 50 to 249 individuals, predation could
pose a significant risk to the long-legged thicketbird. However, there
is insufficient information to determine that predation is ongoing or
has the potential to negatively affect this species.
Summary of Factor C
More information is needed in order to determine the role of
predation, if any, in this species' decline. Currently, there is
insufficient information to determine that threats from predation are
contributing to the species' risk of extinction.
D. The Inadequacy of Existing Regulatory Mechanisms
The long-legged thicketbird is a threatened species under Schedule
1, Section 3 of Fiji's Endangered and Protected Species Act of 2002
(No. 29 of 2002). This law and its implementing regulations (Endangered
and Protected Species Regulations (Act No. 29 2002; Legal Notice No.
64) prohibit trade in the thicketbird, unless permitted. As trade is
not known to be a threat to the thicketbird, this law and its
implementing regulations do not address the conservation needs of the
species.
The thicketbird is also a ``protected bird'' under Fiji's Birds and
Game Protection Act of 1923 (Rev. 1985), as amended. Under this Act it
is illegal to willfully kill, wound, or take any protected bird, or
attempt to sell, possess, or export a protected bird, or their parts,
nests or eggs (Part II, Sec. 3). The penalty for violating this Act is
a fine not to exceed $50, or, if this amount cannot be paid,
imprisonment for up to 3 months (Part IV, Sec. 15) (Birds and Game
Protection Act 1985). As hunting and trapping are not known to be
threats to the thicketbird, this law and its regulations do not address
the conservation needs of the species.
Some of the forest habitat of the long-legged thicketbird is within
the Wabu National Forest Reserve and is protected under Fijian law (BLI
2007i). However, the protections within the reserve are not absolute
and the Forestry Act has a number of serious weaknesses. For example,
legal loopholes permit clearcutting of forests over which the Forestry
Department has no control, and all protected areas established under
the provisions of the Forestry Act are subject to dereservation at the
ministerial level; and reserve forests have frequently been dereserved
(World Conservation Monitoring Centre 1992). In addition, forest
reserves are managed as long-term production forests, with extraction
being allowed by permit (Forest Decree 1992, Part III). In 2003,
experts considered that insufficient
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protection of long-legged thicketbird habitat would lead to a high
probability of habitat conversion or destruction (BLI 2003c; Kirby
2003b). According to Dutson and Masibalavu (2004), BirdLife Fiji is
working with the Department of Forestry to focus on long-term
protection within the Wabu and with local communities to focus on
forest conservation and alternatives to forest destruction, such as
ecotourism, which may help to moderate habitat destruction. However, we
consider this regulatory mechanism to be inadequate in removing or
reducing the primary threat to this species, habitat destruction.
Summary of Factor D
While some of the forest habitat of the long-legged thicketbird is
within the 2-mi\2\ (5-km\2\) Wabu Forest Reserve (Wabu) and is
protected under Fijian law, the regulatory mechanisms in place to
protect the species do not adequately reduce or remove the primary
manmade threat to this species, habitat destruction (Factor A). We
conclude that the inadequacy of existing regulatory mechanisms is a
contributory risk factor that endangers the long-legged thicketbird.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
Two additional factors are considered herein, genetic risks
associated with small population sizes and threats from stochastic
events.
Effect of small population sizes: Small, isolated populations of
wildlife species are susceptible to demographic and genetic problems
(Shaffer 1981). These threat factors, which may act in concert, include
natural variation in survival and reproductive success of individuals,
chance disequilibrium of sex ratios, changes in gene frequencies due to
genetic drift, and diminished genetic diversity and associated effects
due to inbreeding, loss of genetic variation, and accumulation of new
mutations. Inbreeding can have individual and population consequences
by either increasing the phenotypic expression of recessive,
deleterious alleles or by reducing the overall fitness of individuals
in the population (Charlesworth & Charlesworth 1987; Shaffer 1981). In
the absence of more species-specific life history data, a general
approximation of minimum viable population size is referred to as the
50/500 rule (Soul[eacute] 1980; Hunter 1996), described under Factor E
for the black stilt. The available information indicates that, with an
Ne of approximately 50 (BLI 2007i), the long-legged
thicketbird teeters on the edge of the minimum number of individuals
required to avoid imminent risks from inbreeding (Ne = 50).
The current maximum estimate of 249 individuals for the entire
population (BLI 2007i) is only half of the upper threshold
(Ne = 500) required to maintain genetic diversity over time
and to maintain an enhanced capacity to adapt to changing conditions.
As such, we currently consider the species to be at risk due to its
lack of near- and long-term genetic viability.
Threats from stochastic events: Small populations of wildlife
species also susceptible to stochastic environmental events (for
example, severe storms, prolonged drought, extreme cold spells,
wildfire). Stochastic events could result in extensive mortalities from
which the population may be unable to recover, leading to extinction
(Caughley 1994; Charlesworth & Charlesworth 1987). Fiji is susceptible
to damage from tropical storms and cyclones. Tropical storms, which can
sustain winds up to 130 miles per hour (mph) (209 kilometers per hour
(kph)), are common in the South Pacific from November to April
(Ligaiula 2007). Cyclones, also known as typhoons, are storms that
typically form at sea and move inland, generating high winds exceeding
130 mph (209 kph) up to 200 mph (322 kph). Thirteen tropical storms
have hit Fiji in the past 10 years (Associated Press 2007). In December
2007, Cyclone Daman made landfall on Viti Levu, with winds up to 155
mph (250 kph). Trees were destroyed, and heavy rains caused landslides
and flooding in low-lying areas (Ligaiula 2007). The extant long-legged
thicketbird population is extremely small and highly localized (BLI
2003c, 2007i; Kirby 2003b). Therefore, any additional stress to the
population due to stochastic events, such as cyclones, represents a
risk to the species and could lead to a further decline in the species'
abundance or the extent of its occupied range.
Summary of Factor E
In addition to ongoing threats to the species' habitat (see Factor
A), a major risk to the long-legged thicketbird is lack of near- and
long-term genetic viability associated with the extant population's
extremely small size. In addition, the long-legged thicketbird is
vulnerable to reductions in numbers or extinction from stochastic
events, such as cyclones. We consider the species' extremely small
population size, the associated genetic risks and demographic shifts,
and vulnerability to stochastic events to be significant risks that
endanger the long-legged thicketbird throughout its range.
Conclusion and Determination for the Long-Legged Thicketbird
We have carefully assessed the best available scientific and
commercial information regarding the past, present, and potential
future threats faced by the long-legged thicketbird, above. We have
determined that the species is in danger of extinction throughout all
of its known range primarily due to ongoing threats to its habitat
(Factor A), lack of near- and long-term genetic and associated
demographic shifts, and susceptibility to stochastic events due to
risks associated small population sizes (Factor E). Furthermore, we
have determined that the inadequacy of existing regulatory mechanisms
(Factor D) is a contributory risk factor that endangers the species.
Therefore, we are determining endangered status for the long-legged
thicketbird under the Act. Because we find that the long-legged
thicketbird is endangered throughout all of its range, there is no
reason to consider its status in any significant portion of its range.
VI. Socorro Mockingbird (Mimus graysoni)
Species Description
The Socorro mockingbird is a member of the Mimidae family, and
endemic to Socorro Island, Mexico. This species is also referred to as
Socorro thrasher, especially in older literature (e.g., Brattstrom &
Howell 1956). Adults stand about 10 in (25 cm) tall and are mostly
brown, with whitish underparts, darker wings (except for two narrow
bands of white), a dark tail, reddish iris, and dark gape (the soft
tissue at the corner of the mouth) (BLI 2007f; Mart[iacute]nez-
G[oacute]mez & Curry 1998). Male and female Socorro mockingbirds have
similar plumage, but males are larger than females. A juvenile (first-
year bird) can be distinguished from an adult by its plumage, spotted
breast, grayish iris, and yellowish gape (Mart[iacute]nez-G[oacute]mez
& Curry 1998).
Taxonomy
The Socorro mockingbird was first taxonomically described as
Mimodes graysoni (Mimidae family), by Lawrence in 1871. Ornithologists
recognized that the species' behavioral characteristics were
reminiscent of the mockingbird genus, Mimus, of the same family (Barber
et al. 2004). Genetic analysis conducted by Barber et al. (2004)
demonstrated that the species is most closely related to Mimus spp. In
our proposed rule, we referred to this species as Mimodes. However, we
find
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the appropriate taxonomy for the species is Mimus graysoni, which
follows the Integrated Taxonomic Information System (ITIS 2007).
Habitat and Life History
The geography of Socorro Island rises from sea level on the coast
to a height of nearly 3,445 ft (4,000 m) elevation on the peak of Mount
Evermann, in the center of the island (Comisi[oacute]n Nacional de
[Aacute]reas Naturales Protegidas (CONANP) n.d.). Socorro mockingbirds
are found in greatest abundance at elevations above 1,969 ft (600 m)
(Mart[iacute]nez-G[oacute]mez & Curry 1996). They prefer undisturbed
montane areas and primary forests that have a variety of fruit-bearing
plants and a high density of tree species. Dominant plant species in
the Socorro's preferred habitat include holly (Ilex socorrensis),
Guettarda insularis (no common name), and lion's paw (Oreopanax
xalapensis), along with the understory Triumfetta socorrensis and
Eupatorium pacificum (Mart[iacute]nez-G[oacute]mez et al. 2001).
Socorro mockingbirds forage on fruits, invertebrates, and small
arthropods (Mart[iacute]nez-G[oacute]mez et al. 2001). They have been
observed feeding on blowfly larvae on sheep carcasses (Brattstrom &
Howell 1956).
Little is known about the Socorro mockingbird's life history;
breeding information is based largely on studies conducted by
Mart[iacute]nez-G[oacute]mez and Curry (1995) during 1993 and 1994.
They found four nests in 1994, which were located about 12 ft (3.7 m)
off the ground, each in a different species of tree: Holly, Bumelia
socorrensis (no common name), Guettarda insularis (no common name), and
Meliosma nesites (no common name). Researchers inferred that nesting
likely occurs between November and July, with a clutch size of three.
Eggs were incubated by females only (Mart[iacute]nez-G[oacute]mez &
Curry 1998) for no more than 15 days (Mart[iacute]nez-G[oacute]mez &
Curry 1995). A large number of subadults recorded during 1994 suggested
high breeding success for the species (J. Mart[iacute]nez-G[oacute]mez
in litt. via Comisi[oacute]n Nacional Para el Conocimiento y Uso de la
Biodiversidad (CONABIO) February 2007).
Historical Range and Distribution
The Socorro mockingbird is endemic to Socorro Island, Mexico, in
the Revillagigedo archipelago of Mexico. Socorro Island is the largest
of four Revillagigedo Islands, with an approximate land area of 54
mi\2\ (140 km\2\) (Walter 1990). The island is 210 mi (338 km)
southwest of Baja California, Mexico. The Socorro mockingbird was
widespread and common on the island prior to 1958 (Mart[iacute]nez-
G[oacute]mez 2002). Brattstrom and Howell (1956) observed the species
in coastal locations in the southwest part of the Island, inland at
higher elevations, and in canyons on the northern part of the Island.
Socorro mockingbird may have inhabited the southwest portions of the
island only seasonally (R. Curry in litt. February 2007). By the 1980s,
the species was restricted to undegraded fig groves (Ficus
cotinifolia), habitat which was becoming rare (Jehl & Parkes 1982).
Habitat reduction is considered the primary cause of population and
range declines of the Socorro mockingbird (BLI 2000d).
Current Range and Distribution
The current range of the Socorro mockingbird is limited to an
estimated 6 mi2 (15 km2) area. The species is
found in forests above 1,640 ft (500 m) (Martinez-Gomez 2002) and is
most abundant at elevations above 1,969 ft (600 m) around Mt. Evermann
(CONANP n.d.; Martinez-Gomez & Curry 1996; Wehtje et al. 1993).
In our proposed rule (71 FR 67530), we noted, ``the species is less
common in taller forest patches and fig groves at low and mid
elevations.'' Martinez-Gomez (in litt. via CONABIO February 2007)
pointed out that this may be misleading. The field study conducted by
Martinez-Gomez et al. (2001) indicated that the absence of the Socorro
mockingbird in the low-elevation fig grove was due to habitat
degradation. This is discussed further under Factor A.
In our proposed rule, we noted that the species ``is absent from
areas of [croton] Croton masonii scrub near sea-level (Martinez-Gomez &
Curry 1996).'' Curry (in litt. February 2007) clarified that it is
uncertain whether Socorro mockingbird ever inhabited the croton scrub
habitat, except as visitors during the nonbreeding season.
Population Estimates
The Socorro mockingbird was once considered the most abundant
landbird on Socorro Island (Brattstrom & Howell 1956). The population
declined through the 1960s and 1970s, and by 1978 it was feared to be
on the verge of extinction (Jehl & Parkes 1982). In our proposed rule,
we wrote that ``current estimates of population size for the species
range from 50 to 249 individuals (BLI 2000).'' According to Dr. Robert
Curry (Associate Professor, Villanova University, Villanova,
Pennsylvania, in litt. February 2007), there are two problems with this
figure: (1) It does not reflect the most recent field data, but
reflects data collected between 1988 and 1990; (2) it is not an
``estimate'' of the Socorro mockingbird population, but rather the
``category'' to which BirdLife International assigned the species, in
accordance with the IUCN listing criteria. Based on the most recent
surveys, carried out between 1993 and 1994, the estimated population
total was 353 individuals, with a calculated uncertainty of 66
(Martinez-Gomez & Curry 1996). Taking the calculated uncertainty of
this estimate into account, the estimated total population ranged
between 287 and 419 (R. Curry in litt. February 2007). This estimate
was reconfirmed in the summer 2006, when Dr. Juan Martinez-Gomez
(Island Endemics Foundation, Mexico, in litt. via CONABIO February
2007) inspected previous banding areas on the Island. He encountered a
population similar to that studied by Martinez-Gomez and Curry (1996),
above, with an estimated population size between 298 and 408
individuals. While Dr. Martinez-Gomez cautions against extrapolating
these estimates beyond the banding areas studied, he indicated a
likelihood that additional Socorro mockingbirds are on the island (J.
Martinez-Gomez in litt. via CONABIO February 2007).
In our proposed rule, we wrote, ``of 215 birds ringed in 1993-1994,
55 percent were subadults.'' However, Martinez-Gomez (in litt. via
CONABIO February 2007) noted this estimate was erroneously based on the
pooled data from the 1993-1994 banding study conducted by Martinez-
Gomez and Curry (1996), which biased our estimate. The banding for the
2-year study took place at different times of the year: The banding in
1993 took place after the breeding season, and the 1994 banding took
place during the entire breeding season. Thus, in analyzing the 1994
data, which would be more representative of actual age ratios, it was
apparent that sex ratios were not disproportionate and that the
population had produced many young. Thus, the 1994 data suggest that
the species has a high breeding success and that the population may be
successful in recolonizing the area once habitat quality improves (J.
Martinez-Gomez in litt. February 2007).
Conservation Status
The IUCN has listed the Socorro mockingbird as ``Critically
Endangered'' since 2000, due to loss of habitat and the small remaining
number of mature adults (BLI 2007c). The species is categorized as
``Peligro'' in Mexico, meaning it is in danger of extinction (Hesiquio
Benitez Diaz, Director de Enlace y Asuntos Internacionales,
[[Page 3175]]
CONABIO, Tlalpan, Mexico, in litt. February 2007).
Summary of Factors Affecting the Socorro Mockingbird
A. The Present or Threatened Destruction, Modification, or Curtailment
of Socorro Mockingbird's Habitat or Range
Socorro mockingbird habitat in the southern portions of the island
has been severely degraded by construction of a naval base and sheep
overgrazing for the past 50 years. In addition, locust swarms
(Schistocerca piceifrons) have invaded that island since the mid-1990s.
These threats to Socorro mockingbird habitat are discussed in turn.
Naval base: The Mexican Navy built a base on Socorro Island in the
late 1950s (Martinez-Gomez et al. 2001). Built on the southernmost tip,
at Bahia Vargas Lozano, the base supports more than 200 personnel and
family (Wehtje et al. 1993). The Socorro mockingbird prefers
undisturbed montane areas, and may have occupied the area seasonally
before the base was built (R. Curry in litt. February 2007). During
construction, native vegetation was removed from around the base and
replaced with non-native grasses (Martinez-Gomez et al. 2001). Habitat
destruction caused by construction of the naval base contributed to the
species' extirpation from the southern third of the island (BLI 2000d),
although not to the same extent as sheep overgrazing.
Sheep overgrazing: The greatest impact on the habitat of Socorro
Island has been severe degradation due to intensive grazing by
introduced mammals (BLI 2000d; Curry in litt. February 2007; Martinez-
Gomez in litt. February 2007; Martinez-Gomez & Curry 1995, 1996;
Martinez-Gomez et al. 2001). Socorro Island has no native mammals (Jehl
& Parkes 1982). In our proposed rule, we noted that Cody (2005)
reported that Socorro mockingbird habitat is threatened by destruction
from introduced rabbits and pigs. However, Curry (in litt. February
2007) pointed out that, while rabbits and pigs are problematic on the
nearby island of Clarion, these two exotic mammals were never
introduced on Socorro.
Sheep were brought to Socorro Island near the end of the 19th
century and, by 1956, there were an estimated 2,000 sheep living in the
southern portions of the island (Brattstrom & Howell 1956). Left feral,
the sheep overgrazed, creating extensive open areas (2005) and leaving
the soil vulnerable to erosion (R. Curry in litt. February 2007; Wehtje
et al. 1993). The Socorro mockingbird prefers undisturbed montane areas
and forests with a dense understory. In the southern fig forests, hop
bush (Dodonaea viscosa) has replaced the original understory, and these
areas are too degraded for the Socorro to inhabit (Martinez-Gomez et
al. 2001).
Habitat degradation caused by sheep drastically altered habitat on
Socorro Island (BLI 2000d; R. Curry in litt. February 2007; Martinez-
Gomez 2002), especially low- to mid-elevation fig forests (ranging in
altitude from 0 to 1,640 ft (to 500 m)) in the southern portion of the
island (Martinez-Gomez in litt. February 2007). By 1990, they had
overgrazed the southern third of the island (Martinez-Gomez & Curry
1996), where the Socorro mockingbird was once plentiful (Brattstrom &
Howell), although perhaps only seasonally (R. Curry in litt. February
2007). In the northern regions of Socorro Island, low- to mid-elevation
fig forests are largely undegraded and serve as important habitat for
the Socorro mockingbird (Martinez-Gomez & Curry 1996; Martinez-Gomez et
al. 2001). Sheep overgrazing extirpated the species from one-third of
its former range (BLI 2000d).
Locust swarms: Another factor causing the degradation of Socorro
mockingbird habitat was brought to our attention by Martinez-Gomez (in
litt. February 2007). According to Martinez-Gomez (2005), permanent
locust (Schistocerca piceifrons) swarms have invaded the island since
1994. The locusts swarm twice yearly and are capable of reaching all
points on the island. The swarms have defoliated trees and shrubs in
several regions of the island, which decreases the availability of food
from fruit trees and modifies the primary forest habitat which the
species prefers. Locusts are especially pronounced in the southern
portion of the Island. A larger number of young locusts and locusts in
non-swarming stages are found in the degraded habitats in the south
(Martinez-Gomez 2005). Martinez-Gomez (2005) concluded that the higher
intensity of outbreaks in the southern portion of the island was an
indirect result of sheep overgrazing and predation caused by introduced
mammals, namely sheep and cats (see Factor C). Sheep overgrazing has
created open conditions, providing suitable habitat for locust
reproduction, as evidenced by the high number of young and non-swarming
stages of locust found primarily in those areas (Martinez-Gomez 2005).
In the northern portions of the island habitat is less degraded and
bird densities are higher. Less degraded habitat provides less
favorable conditions for the locusts and the swarms are less intense.
Because birds eat locusts, they are better able to moderate the effects
of the swarm, which also drives down the locust population in the
north, where birds are found at higher densities. In the south, locusts
swarms are more intense, and habitat destruction combined with
predation has reduced the number of birds inhabiting the southern
portion of the island. The low bird density in the south is
insufficient to moderate the effects of the swarms being produced
there. Locust swarms have also reduced available food sources, by
denuding the fruit trees of bark which serve as part of the Socorro
mockingbird diet. Martinez-Gomez (2005) attributed the greater and
continued intensity of swarms in the south to the combination of
habitat degradation (which created unsuitable habitat for the birds)
and predation by cats (which reduced the number of birds). We consider
sheep overgrazing to be a factor contributing to the endangerment of
this species.
Summary of Factor A
The current range of the Socorro mockingbird is limited to an
estimated 6-mi2 (15-km2) area. Habitat has been
altered by construction of the Naval base, sheep overgrazing and locust
swarms, compounded by predation (Factor C). Locust swarms have reduced
available food sources by denuding the fruit trees of bark. Preferring
undisturbed montane habitat and primary forest, these factors have
created unsuitable conditions for the species. Overgrazing and locust
swarms continue to threaten the Socorro mockingbird. We believe that
the Socorro mockingbird is at significant risk throughout its range due
to the present and ongoing destruction and modification of its habitat.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
There is no information indicating that the Socorro mockingbird is
being utilized for commercial, recreational, scientific, or educational
purposes. The species is not known to be in international trade and has
not been formally considered for listing under CITES (http://www.cites.org).
C. Disease or Predation
We are not aware of any disease concerns that may have led to the
decline of the Socorro mockingbird species.
Predation by native red-tailed hawks (Buteo jamaicensis
soccoroensis) and
[[Page 3176]]
introduced feral cats is a factor in the species' decline. The red-
tailed hawk is one of two native raptors on the island; the other is
the elf owl (Micrathene whitneyi graysoni), a small insectivore. On the
mainland, red-tailed hawks eat primarily mammals; however, on Socorro
Island their prey consists primarily of birds, land crabs, and lizards
(Jehl & Parkes 1983; Wehtje et al. 1993). In addition, hawks have been
known to prey on adults of other species on the island (Martinez-Gomex
& Curry 1995). Martinez-Gomez and Curry (1995) concluded that nesting
birds and adult Socorro mockingbirds were vulnerable to predation by
red-tailed hawks.
Cats: During their banding study in 1994, Martinez-Gomez and Curry
(1995) reported that hawks and feral cats were likely predators of this
species. Cats were introduced to the island in 1972 (Martinez-Gomez
2002; Martinez-Gomez et al. 2001). Cat predation is considered the
major factor responsible for extirpation of the Socorro dove (Zenaida
graysoni) (Jehl & Parkes 1983). Examinations of cat stomach contents
and scats found no substantive evidence of Socorro mockingbird remains.
However, Curry (in litt. February 2007) and Martinez-Gomez (2002, 2005)
consider that, while feral cats are not the primary reason for the
Socorro mockingbird's decline, in combination with habitat degradation
caused by sheep, predation by cats is contributing to its decline.
Socorro mockingbird fledglings, which are unable to fly for several
days after leaving the nest, and ground-foraging adults are vulnerable
to predation by feral cats (Martinez-Gomez & Curry 1995, 1996).
According to the Center for Tropical Research in Ecology,
Agriculture, and Development (CenTREAD) (2007), eradication of feral
cats from Socorro Island is listed as a primary goal in the draft
management plan for the Biosphere Reserve (CenTREAD 2007). In 2001,
Grupo de Ecologia y Conservacion de Islas, A.C. (GECI), received a
North American Wetlands Conservation Act grant to initiate the
eradication of introduced mammals (including rabbits, pigs and sheep)
from neighboring Clarion Island and to initiate the eradication of cats
and sheep from Socorro Island (Sanchez and Tershy 2001). The work on
Clarion Island was completed (CenTREAD 2007). However, the work on
Socorro Island may prove to be lengthy and daunting. Dr. Bernie Tershy
of the Institute for Marine Sciences (University of California, Santa
Cruz, California), a primary researcher involved in the eradication
programs on Clarion and Socorro Islands, worked with others to review
the documented cases of feral cat eradications on islands and found
only 48 examples (Nogales et al. 2003). Socorro Island has an area of
54 mi2 (140 km2) (Walter 1990) and there are few
examples of eradications on larger islands. Of the 48 examples reviewed
by Nogales et al. (2003), most were conducted on islands smaller than 2
mi2 (5 km2) and only a few on islands larger than
6 mi2 (15 km2). One successful eradication
program on a larger island (Marion Island, Republic of South Africa;
area: 112 mi2 (290 km2)) took place over a 15-
year period. The removal process becomes more complicated when humans
occupy the island, because preventing reintroduction of invasive
species also becomes a factor (Nogales et al. 2003).
Other predators: Feral house mice (Mus musculus), on the other
hand, already present on the island, pose no known threat to the
species (R. Curry in litt. February 2007). Curry (in litt. February
2007) considers the potential accidental introduction of feral black
rats (Rattus rattus) by Naval transport to be a grave potential threat
to the Socorro mockingbird, considering this risk as potentially
devastating as the threat of genetic erosion. Such an introduction has
not yet occurred and, as such, we do not consider predation by rats to
be a factor endangering the species.
Summary of Factor C
Predation by native hawks and feral cats does not appear to be the
primary factor causing this species' decline at this time. However, in
combination with the threat from habitat degradation (Factor A) and the
species' small population size (Factor E), predation is contributing to
the endangerment of the species.
D. The Inadequacy of Existing Regulatory Mechanisms
The General Law of Ecological Equilibrium and Environmental
Protection was enacted on March 1, 1988, and was amended by Decree
published December 13, 1996, and another Decree published January 7,
2000 (General Law of Ecological Equilibrium and Environmental
Protection 2000). This law and its amendments: (1) Established the
authority to designate protected natural areas to safeguard the genetic
diversity of wild species and to preserve species that are in danger of
extinction, are threatened endemics, or are rare, and those that need
special protection (Article 45); (2) prohibit hunting or exploitation
of species within core areas of biosphere reserves (Article 70); (3)
specify that use of natural resources in habitats for endemic,
threatened, or endangered species must be done in a manner that does
not alter the conditions necessary for their survival, development, and
evolution (Article 83); (4) prohibit the unpermitted use of threatened
and endangered species (Article 87); and (5) stipulate penalties for
violation, including fines equivalent to 20 to 20,000 days of the
general minimum wage effective in the Federal District at the time the
sanction is imposed, confiscation of instruments related to violations,
suspension or revocation of permits, and administrative arrest for up
to 36 hours (Article 171). While this overarching environmental law
aims to protect threatened and endangered species, there are no
specific provisions in the law that address the threats to the Socorro
mockingbird (i.e., habitat degradation from introduced mammals, habitat
destruction (Factor A), and predation (Factor C)).
According to the national legislation NOM-059-ECOL-2001, the
species is categorized as ``Peligro,'' meaning it is in danger of
extinction (H. Benitez Diaz in litt. February 2007). Under Mexico's
Wildlife Law (Ley General De Vida Silvestre 2002), it is illegal to
kill, possess, transport, or trade in species in danger of extinction
without a permit (Article 122). As overutilization is not a threat to
the viability of the species, this regulation is of little consequence
to the viability of the Socorro mockingbird.
On June 4, 1994, the Mexican government established the
Revillagigedo Archipelago Biosphere Reserve and declared it to be a
Protected Natural Area (Revillagigedo Archipelago Decree 1994). This
reserve included the entire island of Socorro and established the
following protections: (1) Formulation of a management plan that sets
specific objectives for the reserve (Articles 2 and 3), (2) ban on
construction inside core areas of the reserve (which includes the
entire island of Socorro) (Article 4), (3) requirement of an
environmental impact statement for construction in the buffer zones of
the reserve, (4) ban on the establishment of new human settlements
within the reserve (Article 7), (5) establishment of a ``closed
season'' on all plants and animals in the reserve (Article 9), (6)
prohibition on the dumping or discharge of contaminants (Article 11),
and (7) limit on recreational activities to those identified in the
management plan for the reserve (Article 15). According to the Comision
Nacional de Areas Naturales Protegidas (n.d.), a management plan has
been drafted and is in the process of being published. Management
[[Page 3177]]
recommendations include: Eradicate cats and sheep from the island;
restore the soil and vegetation; and establish a research monitoring
station, especially to monitor the population before and after
eradications (BLI 2007f). If this management plan is finalized and
enacted, this regulatory mechanism has the potential to reduce or
remove threats to habitat and from predation and could ultimately
result in the recovery of the species. However, based on the best
available information at this time, we have no assurances that the
management plan will be completed, implemented, and effective.
Therefore, this regulatory mechanism is inadequate in reducing the
threats to this species.
Summary of Factor D
Regulatory mechanisms are inadequate to reduce the threats to the
species, habitat destruction (Factor A) and predation (Factor C). As
such, we believe that the inadequacy of regulatory mechanisms is a
contributory risk factor that endangers the species.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
Three additional factors are considered herein, genetic risks
associated with small population sizes, hybridization, and threats from
stochastic events.
Genetic risks associated with small population sizes: The small
estimated size of the population, between 298 and 408 individuals
(Mart[iacute]nez-G[oacute]mez & Curry 1996) exposes this species to any
of several risks, including inbreeding depression, loss of genetic
variation, and accumulation of new mutations. Inbreeding can have
individual or population-level consequences either by increasing the
phenotypic expression of recessive, deleterious alleles or by reducing
the overall fitness of individuals in the population (Charlesworth &
Charlesworth 1987). Small, isolated populations of wildlife species are
also susceptible to demographic problems (Shaffer 1981), which may
include reduced reproductive success of individuals and chance
disequilibrium of sex ratios. In the absence of more species-specific
life history data, a general approximation of minimum viable population
sizes is referred to as the 50 / 500 rule (Soul[eacute] 1980; Hunter
1996), as described under Factor E for the black stilt. The available
information indicates that the population of the Socorro mockingbird
may be as small as 298 birds (J. Mart[iacute]nez-G[oacute]mez in litt.
via CONABIO February 2007); this is above the minimum effective
population size required to avoid risks from inbreeding (Ne
= 50). However, the upper limit of the population estimate of no more
than 408 birds (J. Mart[iacute]nez-G[oacute]mez in litt. via CONABIO
February 2007) is near the upper threshold for Ne = 500).
Mart[iacute]nez-G[oacute]mez (2002) notes that the species currently
exhibits a positive reproductive rate, but that demographic problems
will ensue for this species within the next 20 to 30 years, should
habitat degradation continue. We conclude that, combined with the
threats from habitat destruction (Factor A) and predation (Factor C),
this population is vulnerable to genetic risks associated with small
population sizes that negatively impact the species' long-term
viability.
Hybridization: In addition, the potential for the Socorro
mockingbird to hybridize with the northern mockingbird (Mimus
polyglottos) was brought to our attention by Dr. Curry (in litt.
February 2007). The northern mockingbird (Mimus polyglottos) arrived on
the Island in 1978, either naturally or transported by Naval personnel
(Curry in litt. February 2007), and its population has steadily
increased (Jehl & Parkes 1983). Jehl and Parkes (1983) showed that the
northern mockingbird's habitat requirements are different from those of
the Socorro mockingbird and the northern mockingbird, concluding that
the northern mockingbird is not competitively excluding the Socorro
mockingbird. They found that the northern mockingbird's success on the
island was due to its ability to adapt to the island's degraded
habitat. However, it was recently determined that the northern
mockingbird is genetically most closely related to the Socorro
mockingbird (Arbogast et al. 2006; Barber et al. 2004), which increases
the possibility that the two species are capable of hybridizing (R.
Curry in litt. February 2007). In addition, Baptista and
Mart[iacute]nez-G[oacute]mez (2002) noted that song development in
Socorro mockingbird may be being influenced by contact with northern
mockingbirds. Interspecific mimicry could facilitate hybridization
through sexual misimprinting (R. Curry in litt. February 2007).
We recognize that hybridization can lead to genetic dilution and
other genetic risks that undermine the genetic integrity of a species.
There is currently no evidence that hybridization has occurred between
the Socorro mockingbird and the northern mockingbird. As such, we do
not consider this a current factor endangering the species.
Threats from stochastic events: Socorro Island is situated in a
zone with a high probability of being in the trajectory of cyclones
from the Pacific northeast, which form during the months of May to
October. Since 1958, 77 hurricanes and eight tropical storms have hit
the Island chain (Comisi[oacute]n Nacional de [Aacute]reas Naturales
Protegidas (CONANP) n.d.). In 1997, Hurricane Linda came within 46 mi
(74 km; 40 nautical miles (nm)) of the island, where it reportedly
``wreaked havoc'' (Wirth 1998). At 160 knots, it was the strongest
hurricane recorded in the Pacific since recordkeeping began in 1949
(Lawrence 1999).
Socorro Island is a volcanic island. The most recent eruption of
Mt. Evermann occurred in 1993, from an underwater vent off the
southwest coast. Regular volcanic activity continues throughout the
Island from fumaroles and hydrothermal vents (Bulletin of the Global
Volcanism Network 1993). The last major volcanic eruption on Socorro
Island occurred in 1948 (CONANP n.d.) and, according to Trombley
(2007), the next is expected in 2014. An eruption in 1952 on San
Benedicto decimated the native flora and fauna on that island
(Mart[iacute]nez-G[oacute]mez 2002).
Stochastic events, such as hurricanes and volcanic eruptions, could
result in extensive mortalities from which the population may be unable
to recover, leading to extinction. Increased population fragmentation
in combination with these factors increases the likelihood of
extinction of the species through a single stochastic event (Caughley
1994; Charlesworth & Charlesworth 1987).
Summary of Factor E
Combined with the population pressures caused by habitat loss
(Factor A) and predation (Factor C), the Socorro mockingbird is subject
to long-term genetic risks associated with its small population and
compounded by the risk of stochastic events, such as cyclones or
eruptions, severely reducing population numbers such that the species
is unable to recover. We consider the species' small population size
and threats from stochastic events threats that contribute to the
endangerment of the species.
Conclusion and Determination for the Socorro Mockingbird
We have carefully assessed the best available scientific and
commercial information regarding the past, present, and potential
future threats faced by the black stilt, above. We have determined that
the species is in danger of extinction throughout all of its known
range primarily due to ongoing threats
[[Page 3178]]
to its habitats (Factor A) and predation (Factor C), compounded by
genetic risks to the species' long-term genetic viability and
susceptibility to stochastic events due to risks associated small
population sizes (Factor E). Furthermore, we have determined that the
inadequacy of existing regulatory mechanisms is a contributory risk
factor that endangers the species' continued existence (Factor D).
Therefore, we are determining endangered status for the Socorro
mockingbird under the Act. Because we find that the Socorro mockingbird
is endangered throughout all of its range, there is no reason to
consider its status in any significant portion of its range.
Required Determinations
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened under the Act include recognition, recovery actions,
requirements for Federal protection, and prohibitions against certain
practices. Recognition through listing results in public awareness and
encourages and results in conservation actions by Federal governments,
private agencies and groups, and individuals.
Section 7(a) of the Act, as amended, and as implemented by
regulations at 50 CFR part 402, requires Federal agencies to evaluate
their actions within the United States or on the high seas with respect
to any species that is proposed or listed as endangered or threatened,
and with respect to its critical habitat, if any is being designated.
However, given that the black stilt, caerulean paradise-flycatcher,
giant ibis, Gurney's pitta, Long-legged thicketbird, and Socorro
mockingbird are not native to the United States, no critical habitat is
being proposed for designation with this rule.
Section 8(a) of the Act authorizes the provision of limited
financial assistance for the development and management of programs
that the Secretary of the Interior determines to be necessary or useful
for the conservation of endangered species in foreign countries.
Sections 8(b) and 8(c) of the Act authorize the Secretary to encourage
conservation programs for foreign endangered species and to provide
assistance for such programs in the form of personnel and the training
of personnel.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to all endangered
wildlife. As such, these prohibitions would be applicable to the black
stilt, caerulean paradise-flycatcher, giant ibis, Gurney's pitta, Long-
legged thicketbird, and Socorro mockingbird. These prohibitions,
pursuant to 50 CFR 17.21, in part, make it illegal for any person
subject to U.S. jurisdiction to ``take'' (includes harass, harm,
pursue, hunt, shoot, wound, kill, trap, capture, or to attempt any of
these) within the United States or upon the high seas; import or
export; deliver, receive, carry, transport, or ship in interstate or
foreign commerce in the course of commercial activity; or sell or offer
for sale in interstate or foreign commerce any endangered wildlife
species. It also is illegal to possess, sell, deliver, carry,
transport, or ship any such wildlife that has been taken in violation
of the Act. Certain exceptions apply to agents of the Service and State
conservation agencies.
Permits may be issued to carry out otherwise prohibited activities
involving endangered wildlife species under certain circumstances.
Regulations governing permits are codified at 50 CFR 17.22. With regard
to endangered wildlife, a permit may be issued for the following
purposes: for scientific purposes, to enhance the propagation or
survival of the species, and for incidental take in connection with
otherwise lawful activities.
Paperwork Reduction Act
This final rule does not contain any new collections of information
that require approval by the Office of Management and Budget (OMB)
under 44 U.S.C. 3501 et seq. The regulation will not impose new
recordkeeping or reporting requirements on State or local governments,
individuals, businesses, or organizations. We may not conduct or
sponsor and you are not required to respond to a collection of
information unless it displays a currently valid OMB control number.
National Environmental Policy Act
We have determined that environmental assessments and environmental
impact statements, as defined under the authority of the National
Environmental Policy Act of 1969, need not be prepared in connection
with regulations adopted pursuant to section 4(a) of the Act. A notice
outlining our reasons for this determination was published in the
Federal Register on October 25, 1983 (48 FR 49244).
References Cited
A list of the references used to develop this final rule is
available upon request (see ADDRESSES section).
Author
The primary author of this notice is the staff of the Division of
Scientific Authority, U.S. Fish and Wildlife Service (see ADDRESSES
section).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Regulation Promulgation
0
Accordingly, we amend part 17, subchapter B of chapter I, title 50 of
the Code of Federal Regulations, as follows:
PART 17--[AMENDED]
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.
0
2. Amend 17.11(h) by adding new entries for ``Ibis, giant,''
``Mockingbird, Socorro,'' ``Paradise-flycatcher, caerulean,'' ``Pitta,
Gurney's,'' ``Stilt, black,'' and ``Thicketbird, long-legged'' in
alphabetical order under Birds, to the List of Endangered and
Threatened Wildlife as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
-------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
* * * * * * *
Birds
[[Page 3179]]
* * * * * * *
Ibis, giant...................... Pseudibis gigantea.. Cambodia, Lao PDR, Entire............. E 760 NA NA
Thailand, Vietnam.
* * * * * * *
Mockingbird, Socorro............. Mimus Graysoni...... Mexico............. Entire............. E 760 NA NA
* * * * * * *
Paradise-flycatcher, caerulean... Eutrichomyias Indonesia.......... Entire............. E 760 NA NA
rowleyi.
* * * * * * *
Pitta, Gurney's.................. Pitta gurneyi....... Myanmar, Thailand.. Entire............. E 760 NA NA
* * * * * * *
Stilt, black..................... Himantopus New Zealand........ Entire............. E 760 NA NA
novaezelandiae.
* * * * * * *
Thicketbird, long-legged......... Trichocichla rufa... Fiji............... Entire............. E 760 NA NA
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dated: January 7, 2008.
Kenneth Stansell,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. E8-492 Filed 1-15-08; 8:45 am]
BILLING CODE 4310-55-P