Louisiana Waterthrush Habitat Model
go to: USFWS Gulf of Maine Watershed Habitat Analysis
go to: Species Table

Draft Date:
October, 2002

Species:
Louisiana waterthrush, Seiurus motacilla

Use of Study Area Resources:
Reproduction. The Louisiana waterthrush breeds in the.."Eastern United States, from the southern Great Lakes region (including southern Ontario and perhaps rarely in southwestern Quebec) to southern New England; from eastern Texas across the Gulf states to northern Florida" (Cornell Laboratory of Ornithology).  "... Its breeding range is apparently expanding northward into such states as New York, Connecticut, Vermont and Michigan, most likely in response to the reforestation of areas that were extensively lumbered in the late 1800’s and early part of the 20th century... It winters from northern Mexico south through Central America to Panama, also occurring commonly in the Caribbean region and rarely in northern South America. Occasional birds winter within the southeastern United States" (Johns).

Habitat Requirements (Reproduction):
Cover:  "...breeds along the borders of woodland streams, especially fast-flowing ones with gravel bottoms .. flowing through deciduous forest" (Johns).  "Mature deciduous or mixed forests with moderate to sparse undergrowth, near rapid flowing streams" (Robinson 1995, Cornell Laboratory of Ornithology). "...common resident of headwater riparian woodlands, rocky streams, swamps and scrub, thickets and ravines near streams" (Brown et al. 1999). "Moist forest, woodland, and ravines along streams; mature deciduous and mixed floodplain and swamp forests. Prefers areas with moderate to sparse undergrowth (Prosser and Brooks 1998) near rapid-flowing water of hill and mountain streams" (Brown et al. 1999). "Bottomland forests..." (DeGraff and Rudid 1986).

"Essential habitat includes large (probably greater than 100 hectares) tracts of mature, deciduous and deciduous-mixed forest along deep ravines with running water; secondary habitat is characterized by mature, deciduous swamp forest with standing pools of water; generally a forest interior species (McCraken 1991). Headwater streams and wetlands of high water quality and well developed pool and riffle complexes are important (Prosser and Brooks 1998)" (Brown et al. 1999).

"The preferred nest sites are small hollows or cavities near the root base of upturned trees, within the bank of a streamside or under fallen logs. In areas of the state where streams flow through heavily populated areas, there are often excessive amounts of run-off due to extensive impervious surfaces (roads, parking lots, etc.). The result can be flooding during nesting time, with nests, or even eggs or young birds being lost" (Johns).

Avoids high elevations (DeGraaf and Rudis 1986).

Area: Robbins et al. (1989) found Louisiana waterthrush in several middle Atlantic state forests only of 24.7 ha or larger.  Forests smaller than 350 ha had a 50% smaller probability of occurrence than those 3,000 ha or larger.

Foraging: "It forages primarily on the ground along flowing streams, but will also search for food in stagnant pools of water along swamp edges... with extensive probing into crannies in streamside rocks and roots. Prey is also taken from leaves, stems of plants, leaf litter, soil and moss. The main food items taken are aquatic insects and invertebrates, as well as small flying insects. In addition, mollusks, earthworms, crustaceans and even small fish and amphibians may be taken. The waterthrush has an interesting habit of also foraging on floating debris. This bird is an extremely fast feeder, with up to 10 or more feeding maneuvers per minute typical." (Johns).

"Management should focus on protecting core wooded riparian habitat, including establishment or maintenance of a buffer strip of undisturbed riparian forest cover at least 100 meters wide (50 meters each side), and preservation and improvement of water quality to ensure aquatic insect biomass and diversity" (Brown et al. 1999).

Model:
The Breeding Bird Atlas (BBA) data for Maine, New Hampshire and Massachusetts (courtesy of the University of Vermont COOP Unit) were used to identify the range of the Louisiana waterthrush within the study area.  BBA blocks and Breeding Bird Survey (BBS) sites in which Louisiana waterthrushes were known to occur were used to select USDA Forest Service Ecological subunits (Keys et al. 1995); habitat mapping then was restricted to these areas. Elevations within the 'used' BBA blocks also were examined; all occurrences were encompassed within elevations from mean sea level to 430 m.  Therefore, mapping was also restricted to areas below 430 m.

Based on the above sources, we mapped two general types of habitat :

1) Relatively high gradient streams and the adjacent deciduous or mixed woody vegetation. We examined conditions at 7 BBS occurrence sites within the study area, in relation to slope and landcover, and ultimately selected USGS 1:24,000 single-line stream segments along which at least some portions had an average slope of 4 degrees or more. A one cell wide stream channel and the deciduous or mixed upland and wetland deciduous forests and shrub swamp (see table, below) within a 30 m riparian buffer zone was scored as suitable habitat if it was part of a forested area 24.7 ha or larger.

2)  Patches of 'bottomland' forest (wetland deciduous shrub and forest) over 24.7 ha in size.

NWI Designations (wetlands only)	Cover Types	Cover Suitability (0 - 1 scale)
	Upland deciduous forest	1.0**
	Upland coniferous forest
	Upland mixed forest	1.0**
	Grassland
	Upland scrub/shrub
	Cultivated
	Developed
	Bare ground
PEM, L2EM	Lake/pond, emergent vegetation
PFOcon	Palustrine forest, conifer
PFOdec	Palustrine forest, deciduous	1.0**,***
PSSdec	Palustrine scrub shrub, deciduous	1.0**,***
PSScon	Palustrine scrub shrub, conifer
PAB, L2AB	Lake/pond, aquatic vegetation
L1UB, PUB	Lake/pond, unconsolidated bottom
L2US	Lake, unconsolidated shore
L2RS	Lake, rocky shore
R1UB	Riverine subtidal unconsolidated
Rper	Riverine perennial	1.0*
E1AB	Estuarine subtidal vegetated
E1UB	Estuarine subtidal unconsolidated bottom
E2AB	Estuarine intertidal algae
E2EM	Estuarine intertidal emergent
E2RS, R1RS	Estuarine, tidal river rocky shore
E2SS	Estuarine intertidal shrub
E2US	Estuarine intertidal unconsolidated shore
M1AB	Marine subtidal vegetated
M1UB	Marine subtidal unconsolidated bottom
M2AB	Marine intertidal algae
M2RS	Marine intertidal rocky shore
M2US	Marine intertidal unconsolidated shore
NOTES	*if part of a reach with an average slope of 4 degrees or more ** if within 30 m of a 'high gradient' stream *** if part of a wooded wetland > 24.7 ha in area

Model testing: "Most BBS routes are run after the Louisiana waterthrush has finished singing, and do not adequately census the riparian habitat it uses" (Johns), so it was not surprising that occurrences were too infrequent to use for testing the habitat map from the above model. Mapped habitat intersected all 51 BBA blocks within which Louisiana waterthrush are known to breed, but also intersected 254 of 273 randomly chosen BBA blocks within the range, a significantly different proportion (Chi-square signif. < .03).

A data set of 28 Louisiana waterthrush occurrences was obtained from Tom Hodgman (Maine Department of Inland Fisheries and Wildlife) subsequent to development of this model. These were results of a 2000 survey (T.P. Hodgman and P.U. Wilson unpub.) of 60 southern Maine stream riparian areas. Mapped habitat intersected 24 of the 28 sites, in comparison with 46 of 357 equivalent randomly chosen non- open water sites in the model's range, a highly significant difference.

Sources:

Brown, B., M. Koenen and D.W. Mehlman. 1999. Species Management Abstract: Louisiana Waterthrush (Seiurus motacilla). THE NATURE CONSERVANCY, 4245 North Fairfax Drive, Suite 100, Arlington, VA 2220; downloaded 10/01.

Cornell Laboratory of Ornithology. http://birds.cornell.edu/bfl/speciesaccts/louwat.html; downloaded 11/01

DeGraaf, R.M. and D.D. Rudis. 1986. New England Wildlife: Habitat, Natural History and Distribution. USDA Technical Report NE-108.

Johns, M. Louisiana Waterthrush (Seiurus motacilla). North Carolina Partners in Flight, species profiles, http://faculty.ncwc.edu/mbrooks/pif/Bird%20Profiles/louisiana_waterthrush.htm; downloaded 11/01.

Keys, J.E., Jr., J.C. Carpenter, S. Hooks, F. Koenig, W.H. McNab, W. Russell and W. Smith. 1995. Ecological units of the eastern United States - first approximation (map and booklet of map unit tables), USDA Forest Service. Atlanta, GA.

Robbins, C.R., D.K. Dawson and B.A. Dowell. 1989. Habitat area requirements of breeding forest birds of the middle Atlantic states. Wildl. Monogr. 103:1-34.

Robinson, W.D. 1995. Louisiana Waterthrush, Seiurus motacilla. In A. Poole and F. Gill, (eds.) The Birds of North America, No. 151. The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D.C.