Sedge Wren Habitat Model
go to: USFWS Gulf of Maine Watershed Habitat Analysis
go to: Species Table
Feedback: We welcome your suggestions on improving this model!

Draft Date:
June 2001

Species:
Sedge wren, Cistothorus platensis. Formerly known as short-billed marsh wren; the name was changed to distinguish it from the marsh wren, C. palustris.

Use of Study Area Resources:
Reproduction. Within the study area sedge wrens have a scattered and sparse distribution. They breed in southern New Hampshire, southern Maine, and much of Massachusetts. Sedge wrens are listed as endangered by all three states. They winter in the Atlantic coastal states from Virginia through the Gulf coast, to Mexico.

Habitat Requirements:
Sedge wrens use densely vegetated sedge meadows, wet hayfields, upland margins of ponds and marshes, and coastal brackish marshes (Gibbs and Melvin 1992). They prefer drier marshes or wet meadows where there is little standing water and the ground is damp (Bent 1958), and "thick grassy areas in blueberry barrens" (Palmer 1949). Forbush (1929) found them in "wet grassy meadows through which flows a small stream or river, often bordered by alder thickets, or in the upper reaches of a marsh where there is comparatively little water." Sedge wrens have low fidelity to both breeding and wintering sites, and readily abandon areas that become too wet or too dry through water level fluctuation (Gibbs and Melvin 1992, Forbush 1929). The available information suggests that sedge meadows, which offer saturated soils, with or without shallow standing water, are optimal nesting habitat, and that other types may be used when optimal habitat is unavailable or of limited availability.

Nesting in the northeast is initiated in late June or July (Gibbs and Melvin 1992) and may coincide with seasonal stability of water levels in preferred habitats. Dechant et al. (2001) noted in their review of this species that habitat use appeared to vary with annual precipitation; nests in drier years were founding hayfields and grasslands, while in wet years nesting habitats ranged from wetlands and short grass (30 cm) with standing water (2 cm), to the edges of dry hillsides. In New England, Bagg and Eliot (1937 in Gibbs and Melvin 1992) suggested “that sedge wrens colonized wet meadows early in the nesting season, but due to summer drying, used permanently wet, tussocky marshland in July for renesting”.  Palmer (1949) noted that nests were hidden “deep down” in thick sedges, grasses, “or other low herbage, close to the ground, mud, or very shallow water, not more than a foot or two above it at the most”. They may breed in colonies of from 5 to over 100 pairs (Palmer 1949).

Foraging. Principal foods consist of insects and spiders gleaned from the ground and surrounding vegetation (NPWRC 1999). Common foods include ants, bugs, beetles, grasshoppers, crickets, flies, mosquitos, moths, and caterpillars (Bent 1948; Howell 1932, Warren 1980, and Walkinshaw 1935 in Gibbs and Melvin 1992).

Special Requirements. Prolonged use of an area may depend on stable soil moisture regime. There is little information on minimum patch size requirement. In Maine Knight (1908) found sedge wrens breeding in a "fresh water meadow of a few acres extent". Gibbs and Melvin (1992) stated that protected areas should be > 5 ha in extent. In Illinois, Schramm et al. (1986 in Dechant et al. 2001) found a 3.4 ha minimum habitat area for burned prairie.

Habitat Mapping:
The sedge wren model identified wet grassland and sedge covers that were within its known range (see below), and which had a minimum area of approximately 2 acres (8 30-m cells). Wet grassland and sedge cover types were identified from the available data (see table, below) by selecting the edges of upland grassy areas which adjoined  (within 60 m of) palustrine wetland types, or grasslands over moist soils. We also included emergent freshwater and estuarine wetlands which were adjacent to upland forest, grassland, or upland shrub/scrub covers. To this we added freshwater emergent wetlands adjacent to streams.

NWI Designations (wetlands only)	Cover Types	Cover Suitability (0 - 1 scale)
	Upland deciduous forest
	Upland coniferous forest
	Upland mixed forest
	Grassland	1.0*
	Upland scrub/shrub
	Cultivated
	Developed
	Bare ground
PEM, L2EM	Lake/pond, emergent vegetation	1.0**
PFOcon	Palustrine forest, conifer
PFOdec	Palustrine forest, deciduous
PSSdec	Palustrine scrub shrub, deciduous
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
E1AB	Estuarine subtidal vegetated
E1UB	Estuarine subtidal unconsolidated bottom
E2AB	Estuarine intertidal algae
E2EM	Estuarine intertidal emergent	1.0**
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	*score if within 60 m of palustrine emergent, shrub or forested cover types, or on wet soils **score if within 60 m of upland forest, grassland, upland shrub/scrub, or streams

Range. The Breeding Bird Atlas data for Maine, New Hampshire and Massachusetts (courtesy of the University of Vermont COOP Unit), and the Maine Department of Inland Fisheries and Wildlife heritage database, were used to identify the range of the sedge wren within the study area. The range for modeling was delineated by including all USDA Forest Service Ecological subunits (Keys et al. 1995) in which sedge wrens were know to occur. Habitat mapping then was restricted to these areas.

Area. A minimum patch size of 1.8 acres (8 cells) was adopted to match the "few acres" mentioned by Knight (1908); area > 1.8 acres (0.7 ha) = 1.0, smaller area = 0.

Habitat Scores: were the product of the cover type suitability value and area suitability value, within the identified range.

Model testing. Eight sites in Maine, one in New Hampshire, and two areas in Massachusetts were known breeding areas for sedge wren. These were used in model development (inspection of landcover associated with the occurrence), and so could not be used to test the accuracy of the model. The model output predicted or identified habitat at 9 of the 11 occurrences.

Sources:
Bent, A.C. 1958. Life Histories of N.A. Nuthatches, Wrens, Thrashers and Their Allies. U.S. National Museum Bull. 195. U.S. National Museum. Washington, D.C.

Dechant, J.A., M.L. Sondreal, D.H. Johnson, L.D. Igl, C.M. Goldade, B.D. Parkin and B.R. Euliss. 2001. Effects of management practices on grassland birds: Sedge Wren. Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/literatr/grasbird/sewr/sewr.htm (Version 17FEB2000).

Forbush, E.H. 1929. Birds of Massachusetts and Other New England States. Commonwealth of Massachusetts, Norwood, MA. pp 348-350.

Gibbs, J.P. and S.M. Melvin. 1992. Sedge Wren, Cistothorus platensis. Pages 191-209 In Schneider K.J. and D.M. Pence (eds.) Migratory Non-game Birds of Management Concern in the Northeast. USDI Fish and Wildlife Service, Region 5, Newton Corner, MA. 400 pp.

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.

Knight, O.W. 1908. The Birds of Maine. C.H. Glass, Bangor, ME. 693 pp.

Palmer, R. 1949. Maine Birds. Bull. Of Comparative Zoology, Vol. 102. Harvard College, Cambridge, MA. 656 pp.