Part
2, Sec. 2B2
Sanctuary
Resources - Natural Resources
Seabirds
g.
Seabirds
Over
40 species of marine birds are found throughout the year in
the southwestern Gulf of Maine (Payne and Seltzer, 1986). Although
they return to land to breed, seabirds spend anywhere from 50
to 90 percent of their lives at sea, foraging and competing
with other predators for food (Fisher and Lockley, 1954; Ainley,
1980). Distribution and abundance of seabird species at Stellwagen
Bank are related, as they are in other parts of the Gulf of
Maine, to the availability of preferred prey (e.g., fish and
fish larvae, cephalopods, crustaceans, and offal). Various seabird
species are often specialized in their feeding behavior, resulting
in little overlap in preferred prey species. This occurs even
among closely related species, such as the several species of
shearwaters found in the Gulf of Maine region (Powers and Brown,
1987). The high levels of biological productivity at Stellwagen
Bank, combined with the presence of fishing vessels, result
in a predictable and abundant variety of associated species
of both coastal and pelagic seabird species.
There
are ten species groups of marine birds which are generally dominant
in the southwestern Gulf of Maine (Table 2). In addition to
these species groups, several species of scoters occur in the
Stellwagen Bank area, as well as eiders, mergansers, and oldsquaws
(Payne and Seltzer, 1986). These species include:
Melanitta
deglandi, White-winged scoter (sea duck)
M.
negri, Black scoter (or sea duck)
M.
perspicillata, Surf scoter (or sea duck)
Somateria
mollisima, Red-Breasted merganser
Clangula
hyemalis, Oldsquaw
Additional
occasionally-seen migratory species include the Sharp shinned
hawk (Accipiter striatus), Osprey (Pandion
haliaetus), Peregrine falcon (Falco peregrinus),
and Atlantic brant (Branta bernicla hrota).
With
a single exception (Leach's storm petrel, Oceanodroma
leucorhoa), all seabirds occurring around the Stellwagen
Bank area are either migrants or non-breeding residents. In
general, spring months are the time of greatest seabird abundance
on the Bank. (Powers and Brown, 1987)
It
is possible that some limited hunting for sea duck species (such
as oldsquaws, mergansers, scoters, and eiders) may occur within
the area of the Sanctuary, pursuant to licenses issued under
the Migratory Bird Treaty Act (MBTA). However, as most sea duck
hunting occurs in sheltered bays or inlets adjacent to land,
hunting near the open ocean Stellwagen Bank is likely to occur
only on an infrequent basis, if at all. (V. Lang, USFWS, pers.
comm., June 1991).
U.S.
Fish and Wildlife Service analysis of National Marine Fisheries
Service sea sampling data (1989-1990) also indicates that incidental
take of sea bird species generally resulting from commercial
or recreational fishing activities does not happen frequently,
or pose an exploitation threat to any species. (V. Lang, USFWS,
pers. comm., June 1991).
Table
2: Species/Species Groups of Marine Birds Occurring in the Southwestern
Gulf of Maine
Group Species/Common
Name
Loons
Gavis immer, Common Loon
G.
stellata, Red-throated Loon
Albatross
Diomedea spp., albatross
Fulmars
Fulmarus glacialis, Northern Fulmar
Shearwaters
Calonectris diomedea, Corey's Shearwater
Puffinus
gravis, Greater Shearwater
P.
griseus, Sooty Shearwater
P.
puffinus, Manx Shearwater
Storm
Petrals
Oceanites oceanicus, Wilson's storm petral
Oceanodroma
leucorhoa, Leach's strom petral
Gannets
Sula bassanus, Northern Gannet
Cormorants
Phalacrocorax carbo,Great cormorant
P.
auritus, Double-crested cormorant
Phalaropes
Phalaropus fulicaria,Red phalarope
P.
lobatus, Red-necked phalarope
Alcids
Alca torda, Razorbill
Uria
aalge, Thin-billed (common) murre
U.
lomvia, Thick-billed (Brunnich's) murre
Alle,
Dovekie
Cepphus
grylle, Black guillemot
Fratercula
arctica, Atlantic (Common) puffin
Gulls
Larus hyperboreus, Glacuous gull
L.
glaucoides, Iceland gull
L.
marinus, Great Black-backed gull
L.
argentatus, Herring gull
L.
delawarensis, Ring-billed gull
L.
atricilla, Laughing gull
L.
philadelphia, Bonaparte's gull
Xema
sabini, Sabine's gull
Rissa
tridactyla, Black-legged kittiwake
Jaegers
Stercorarius pomarinus, Pomarine jaeger
S.
parasiticus, Parasitic jaeger
S.
longicaudus, Long-tailed jaeger
Skuas
Catharacta skua, Great skua
C.
maccormickii, South polar skua
Terns
Sterna hirundo, Common tern
S.
paradisaea, Arctic tern
S.
dougalii, Roseate tern
S.
albifrons, Least tern
S.
maxima, Royal tern
S.
sandivicensis, Sandwich tern
S.
anaethetus, Bridled tern
S.
fuscata, Sooty tern
Chlidonias
niger, Black tern
Loons
- The Common loon (Gavis immer), and the
Red-throated loon (Gavis stellata) breed
in northeastern North America and migrate along the Atlantic
seaboard. While Red-throated loons are primarily found in nearshore
waters and the western margin of the Gulf of Maine, Common loons
additionally cross over Georges Bank during May and November.
Loons are pursuit divers, feeding as tertiary carnivores, primarily
on fishes, and as secondary carnivores on crustaceans, mollusks,
and aquatic insects (Palmer, 1962). Loons have been recorded
frequently offshore during spring and fall migrations.
Albatrosses
- Two species of albatrosses, the Yellow-nosed (Diomedea
chlororhynchos) and the Black-browed (D.
melanophris), are considered rare visitors to western
North Atlantic waters; at least one yellow-nosed albatross was
reported on Georges Bank in 1976 (Powers and Brown, 1987).
Fulmars
- The Northern fulmar (Fulmarus glacialis).
The pelagic distribution of northern fulmars encompasses the
North Atlantic; in the Western North Atlantic, fulmars extend
as far south as the Mid-Atlantic Bight. As "opportunistic" secondary
and tertiary carnivores, fulmars consume a large variety of
zooplankton, fish, squid, crustaceans, and offal from fishing
vessels. They are found off the New England coast throughout
the year, with the exception of August, when they move northward.
Peak abundance over the Stellwagen Bank/Georges Bank area is
usually from approximately January to April, when flocks of
several thousands have been recorded (Powers, 1983).
Shearwaters
- Four species of shearwaters occur with regularity over
the Stellwagen Bank/Georges Bank area: Cory's shearwater
(Calonectris diomedea); Greater shearwater
(Puffinus gravis); Sooty shearwater (P.
griseus); and Manx shearwater (P. puffinus).
A fifth species, Audubon's shearwater (Puffinus lherminieri),
normally is found on southern edges of Georges Bank during the
summer.
Cory's
shearwaters are abundant in New England waters generally from
July until October; and in some years significant numbers of
this species have moved into the Gulf of Maine and stayed until
the autumn (Powers and Brown, 1983). The largest local concentrations
have occasionally been recorded at 30-100 birds/km2 (Powers,
1983). The species feeds at or near the surface as secondary
and tertiary carnivores on fish, fish larvae, cephalopods, and
crustaceans.
The
Greater shearwater is highly abundant over Georges Bank, beginning
in May and peaking in June and July, when densities may reach
25 birds/km2. The species is most numerous over Stellwagen Bank
during summer and autumn months. Like the Cory's, the Greater
shearwater feeds as a tertiary carnivore on fish and cephalopods;
as a secondary carnivore on crustaceans; and as a scavenger
on offal from fishing vessels.
Between
May and September, Sooty shearwaters migrate in a clockwise
manner around the North Atlantic basin; they are abundant on
Georges Bank from late May to mid-July, and are found over Stellwagen
Bank during the summer months. Typically, the species feeds
at or near the surface as a secondary or tertiary carnivore
on fish, cephalopods, and crustaceans; however, this species
does not appear as frequently in association with fishing vessels
as other shearwaters (Wahl and Heinemann, 1979).
Manx
shearwaters occur over Georges Bank from June to October (Powers
and Brown, 1983); and are occasionally seen over Stellwagen
Bank during summer months. Like other shearwaters, the Manx
is a secondary and a tertiary carnivore, feeding on small fish,
cephalopods, crustaceans, and probably offal.
Storm
Petrels - Of the two species of storm petrels occurring
in and around the Stellwagen Bank area, Wilson's (Oceanites
oceanicus) and Leach's (Oceanodroma leucorhoa),
the Wilson's is by far the more commonly-seen.
Wilson's
storm petrels arrive in the Gulf of Maine by late May, and reside
through the summer months; this residency largely coincides
with the seasonal peak in zooplankton. The species is primarily
a surface-feeder on zooplankton, euphausiids, and amphipods,
and (to a lesser degree) as a tertiary carnivore on small fish
and cephalopods. Also known as Mother Carey's chick (Powers
and Brown, 1983), the Wilson's storm petrel is the second most
abundant seabird species during the summer over the Georges
Bank/Stellwagen Bank area.
Leach's
storm petrels are also found in this region between April and
November, although they are more abundant on the Southern Scotian
Shelf, to the north. This is the only seabird species which
utilizes northern areas as breeding habitat, in particular,
the Bay of Fundy region (Powers and Brown, 1983).
Gannets
and Cormorants - The Northern gannet (Sula
bassanus) are tertiary carnivores feeding almost exclusively
on fish and squid, although the species is known to scavenge
offal from fishing vessels and may also take fish directly from
fishing nets near the surface (Powers, 1983). Gannets are most
numerous in the Gulf of Maine, and in particular over Stellwagen
Bank and through the Great South Channel. During winter-spring,
large concentrations of gannets have been observed feeding in
association with cetaceans (Payne and Seltzer, 1986).
Two
species of cormorants occur very occasionally over Stellwagen
Bank; they are more typically coastal inhabitants.
The
Great cormorant (Phalacrocorax carbo) and
the Double-crested cormorant (Phalacrocorax auritus)
exhibit migratory movements in the spring and autumn in the
western Gulf of Maine, and feed primarily on fish.
Phalaropes
- Of the two species known to occur occasionally in the vicinity
of Georges Bank/Stellwagen Bank, the Red phalarope (Phalaropus
fulicaria) is more frequently observed than the Red-necked,
or Northern, phalarope (Phalaropus lobatus).
Both species are most common during April to June, and again
during August to October, during migratory passages. The spring
migration northward occurs largely along the outer edge of the
shelf (60 to 200 meters, or 196.8 to 656 feet); although some
of both species have been known to follow the coast into the
western Gulf of Maine on their northward migration (Powers,
1983). Both species feed at the surface as secondary carnivores
on planktonic crustaceans, fish and squid eggs, and larvae.
Alcids
- At least five, and possibly six species of alcids occur
in the Gulf of Maine/Stellwagen Bank vicinity. Razorbills
(Alca torda) are pursuit-diving birds, feeding
as secondary and tertiary carnivores on crustaceans and fish.
The species is present in the area from late November to May,
most commonly in shoal areas around Cape Cod, over the Great
South Channel, and along northern parts of Georges Bank. The
Georges Bank area appears to be an important wintering area
for this species (Powers and Brown, 1983).
Two
species of murres, the Thin-billed, or Common (Uria
aalge) and the Thick-billed, or Brunnich's (Uria
lomvia), are occasionally seen during the winter in the
southern Gulf of Maine, including areas around Stellwagen Bank.
By March, these species are more common on northeast Georges
Bank and over the Northeast Channel to the north. Murres and
razorbills are all large auks, with similar feeding habits.
Murres are pursuit-divers, feeding as secondary and tertiary
carnivores on crustaceans, fish and cephalopods.
Dovekies
(Alle) are generally observed from December to May in
the Gulf of Maine, and also south across the Nantucket Shoals.
The species feeds as a secondary carnivore on crustaceans, and
may also eat zooplankton.
Black
guillemot (Depphus grylle) are also a pursuit-diving
birds, feeding as secondary and tertiary carnivores on benthic
crustaceans and mollusks, and fish. The Black guillemot is primarily
a coastal inhabitant, but is occasionally seen over Stellwagen
Bank.
The
Atlantic, or Common, puffin (Fratercula arctica)
is found between November and early June over Georges Bank;
little is known about its distribution. Like other alcids, puffins
are pursuit-divers, feeding almost exclusively on fish as tertiary
carnivores.
Gulls,
Jaegers, and Skuas - Eight species of gulls occur with regularity
in the southwestern Gulf of Maine, and over Stellwagen Bank.
Among these, the Herring gull (Larus argentatus)
and the Great black-backed gull (Larus marinus)
occur in greatest numbers over Stellwagen Bank. Both species
are omnivorous, feeding as secondary, tertiary, and upper level
carnivores on crustaceans, insects, fish, squids, birds and
eggs, and as scavengers on offal and carrion. Large numbers
of both species are closely associated with fishing vessel activities
throughout the year.
Glaucous
gulls (Larus hyperboreus) and Iceland gulls
(Larus glauacoides glaucoids) also feed
as secondary, tertiary, and upper level carnivores on macrozooplankton,
fish, and offal, as well as on the eggs and young of other seabirds.
Both species are seen in the Gulf of Maine region from the autumn
through the spring, commonly in association with Herring and
Great black-backed gulls following fishing vessels.
Laughing
gulls (Larus atricilla) are usually seen during
summer months in the Gulf of Maine, surface feeding on small
fish and scavenging on offal. This species is also known to
take the eggs of terns on land.
Ring-billed
gulls (Larus delawarensis), Bonaparte's
gulls (Larus philadelphis), and Sabine's
gulls (Xema sabini) all appear in offshore
areas throughout the Gulf of Maine during migratory periods
only.
Like
the gulls, the Black-legged kittiwakes (Rissa
tridactyla) feed as secondary and tertiary carnivores
on crustaceans, fish and squid, in addition to offal. The species
is extremely abundant during November to March, particularly
in the area from Jeffreys Ledge south and east across the northern
portion of Georges Bank. In winter months, the density of kittiwakes
over Stellwagen Bank and Jeffreys Ledge is probably higher than
for any other species of seabird.
Three
species of jaegers occur in the western North Atlantic, although
only two are regularly observed in the southwestern Gulf of
Maine, over Stellwagen Bank: the Parasitic jaeger (Stercorarius
parasiticus) and the Pomarine jaeger (Stercorarius
pomarinus). The Long-tailed jaeger (Stercorarius
longicaudus) is only seen very occasionally in the Gulf.
Jaegers are migrants across Georges Bank, principally in spring
and fall months. Jaegers feed at the surface, seizing prey or
snatching from other birds, such as gulls and terns. The species
are secondary and tertiary carnivores feeding on crustaceans,
fish and cephalopods, as well as offal.
Two
species of skuas appear over Georges Bank and the surrounding
areas, the Great skua (Catharacta skua)
and the South polar skua (Catharacta maccormickii).
The great skua is most common from October to March, although
individual sightings have been made every month (Powers and
Brown, 1983). The south polar skua, only recently recognized
in the overall western North Atlantic, has been generally observed
from May to October over Georges Bank. Like the jaegers, skuas
feed primarily on fish, cephalopods, and offal.
Terns
- All nine species of terns identified as occurring around the
Stellwagen Bank region feed exclusively on small fish. Of the
group, it is known that Common terns (Sterna hirundo),
Arctic terns (Sterna paradisaea), Roseate
terns (Sterna dougallii), and Least terns
(Sterna albifrons) breed along Atlantic coastlines
at various points, depending on the individual species, between
Nova Scotia and Florida (and, in the case of the Least tern,
also along the Gulf coast). Terns are typically seen around
the Bank during summer and autumn months. The roseate tern is
Federally-listed as an endangered species.
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