Saltmarsh Sharp-tailed Sparrow Habitat Model
go to: USFWS Gulf of Maine Watershed Habitat Analysis
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Draft Date:
June 2001

Species:
Saltmarsh sharp-tailed sparrow, Ammodramus caudacutus. This species was described by Greenlaw (1993); A. nelsoni, which is closely related also occurs in Maine, typically in more freshwater environments (Tom Hodgman, pers. com., Maine Department of Inland Fisheries and Wildlife).

Use of Study Area Resources:
The saltmarsh sharp-tailed sparrow occurs from New Jersey north through mid-coast Maine (Greenlaw and Rising 1994). Montagna (1942) found them in summer as far northeast as Popham Beach, and wintering occasionally as far north as Massachusetts. Tom Hodgman, (pers. com.), observed saltmarsh sharp-tailed sparrows as far north as South Thomaston, Maine, though not in relatively low salinity marshes along the major rivers.

Habitat Requirements:
Cover. In the Northeast the saltmarsh sharp-tailed sparrow is found in salt marsh/meadows (Spartina alterniflora, S. patens), needlerush (Juncus gerardii), from just below to well above mean high water (Pierson et al. 1996). It nests in clumps or thatch of grasses, slightly elevated above the soil surface (Greenlaw and Rising 1994). Overarching vegetation or wrack usually canopy the nest (Greenlaw and Rising 1994).  Successful nesting may be limited to areas above spring high tides, although nesting and fledging may be accomplished between spring tide events.

Foraging. Sharp-tailed sparrows feed almost exclusively on insects, spiders and small invertebrates during the breeding season, switching to seeds of grasses and other plants in the fall and winter as other prey become less available (Greenlaw and Rising 1994). They feed on the ground in dense grass, at the edges of pools and pannes, and in patches of wrack (Greenlaw and Rising 1994).

Limiting Factors. Flooding is the most common cause of nest failure. Predators include northern harrier, short-eared owl, crows, rats, red fox, raccoon, and occasionally snakes (Greenlaw and Rising 1994).

Model:
Nesting habitat was delineated by selecting infrequently flooded estuarine intertidal marsh (see table, below) from National Wetland Inventory digital maps, within the breeding range of the sparrow (New Jersey northeast to South Thomaston ME, Tom Hodgman pers. com.). Small areas of high marsh adjoining urban areas (e.g., around Boston) were eliminated from consideration as were low-salinity marshes along major rivers (e.g., Saco River, Kennebec River).

Maine Department of Inland Fisheries and Wildlife survey data (Tom Hodgman, unpublished) were overlaid on the delineated high marsh. Hodgman observed saltmarsh sharp-tailed sparrows in marsh patches as small as about 0.5 ha. Accordingly, smaller patches of high marsh (less than 0.5 ha) were scored 0.3. Larger patches were scored 0.7, and patches in which saltmarsh sharp-tailed or unidentified sharp-tailed sparrows were observed were scored 1.0.
NWI Designations
(wetlands only)
Cover Types Cover Suitability
(0 - 1 scale)
Upland deciduous forest
Upland coniferous forest
Upland mixed forest
Grassland
Upland scrub/shrub
Cultivated
Developed
Bare ground
PEM, L2EM Lake/pond, emergent vegetation
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 * upper intertidal, infrequently flooded

Sources:

Greenlaw, J.S. 1993. Behavioral and morphological diversification in sharp-tailed sparrows (Ammodramus caudacutus) of the Atlantic Coast. Auk 110(2):286-303.

Greenlaw, J.S. and J.D. Rising. 1994. Sharp-tailed sparrow, Ammodramus caudacutus. In The Birds of North America, No. 112 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D.C.

Montagna, W. 1942. The sharp-tailed sparrows of the Atlantic coast. Wilson Bulletin 54(2):107-120.

Pierson, E.C., J E. Pierson and P.D. Vickery. 1996. A Birders Guide to Maine. Down East Books, Camden, ME.