American Whimbrel Habitat Model
go to: USFWS Gulf of Maine Watershed Habitat Analysis
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Draft Date:
March, 2001

Species:
American whimbrel, Numenius phaeopus hudsonicus

Use of Study Area Resources:
Whimbrels migrate through the study area, using primarily coastal areas in spring, and a combination of coastal and inland areas in the Fall (Pierson et al. 1996, Skeel and Mallory 1996). In North America, whimbrels breed in subarctic zones on tundra and taiga, often with associated marshes. They winter along coastal areas of North America, from California and the Carolinas southward through South America (Johnsgard 1981, Skeel and Mallory 1996).

Habitat Types:
Whimbrels are flexible in their foraging behavior and can take advantage of a variety of habitats, concentrating on the most profitable prey (Turpie and Hockey 1997). In coastal areas they forage on intertidal flats, beaches, estuaries, rocky shores, salt marshes and dunes for marine invertebrates, including crustaceans, worms, and molluscs (Skeel & Mallory 1996). Their bill is adapted to fit the curve of the fiddler crab (Uca spp.) burrow (Johnsgard 1981, Velasques and Navarro 1993, Skeel & Mallory 1996). Inland foraging sites include heaths, wet meadows, farmland, and grasslands. Food items include berries (blueberries, huckleberries, crow berries, and cloudberries), insects (beetles, grasshoppers, crickets), and spiders (Mackay 1892, Glutz et al. 1977 in Johnsgard 1981, Hayman et al. 1986, Montevecchi and Tuck 1987 in Skeel and Mallory 1996).

Model:
The habitat models relied on abundance/occurrence information from a Maine Department of Inland Fisheries and Wildlife (MDIFW) shorebird coverage, and the Manomet Bird Observatory's International Shorebird Survey (ISS) database for Massachusetts and New Hampshire. The occurrence information was used to select the general localities used by the species. Environmental data sets (bathymetry and wetland cover type) were used to select areas within those localities likely to have been used. The ISS data specified the observation locations only to the nearest minute, so all suitable cover types (see table, below) within a 1 km radius of those points were regarded as having the level of use indicated at the observation point.

NWI Designations
(wetlands only)
Cover Types Cover Suitability
(0 - 1 scale)
Upland deciduous forest
Upland coniferous forest
Upland mixed forest
Grassland 0.5*
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 1.0
L2RS Lake, rocky shore
R1UB Riverine subtidal unconsolidated
Rper Riverine perennial
E1AB Estuarine subtidal vegetated
E1UB Estuarine subtidal unconsolidated bottom
E2AB Estuarine intertidal algae 0.5
E2EM Estuarine intertidal emergent 1.0
E2RS, R1RS Estuarine, tidal river rocky shore 0.5
E2SS Estuarine intertidal shrub
E2US, R1US Estuarine, riverine intertidal unconsolidated shore 1.0
M1AB Marine subtidal vegetated
M1UB Marine subtidal unconsolidated bottom
M2AB Marine intertidal algae 0.5
M2RS Marine intertidal rocky shore 0.5
M2US Marine intertidal unconsolidated shore 1.0
NOTES * patches > 1 ha only

Habitat Suitability Scoring: Sites with whimbrel occurrences and having any of the suitable landcover types (see table) first were scored according to level of use. If a site had 5 or more birds observed at any time, the suitability index = 1.0; else, if any birds were present the suitability index = 0.5. Then this value was multiplied by the landcover score.

Suitable cover types outside of the observation/occurrence polygons were scored as potential foraging habitats; unconsolidated sediment cover types were re-scored 0.2; grassland, marsh and rocky types were re-scored 0.1.

Sources:
Hayman, P., J. Marchant and T. Prater. 1986. Shorebirds: an Identification Guide to the Waders of the World. Houghton Mifflin Co., Boston, MA. 412 pp.

Johnsgard, P.A. 1981. The Plovers, Sandpipers and Snipes of the World. University of Nebraska Press. Lincoln, NE. 493 pp.

Mackay, G.H. 1892. Habits of the Hudsonian Curlew in Massachusetts. Auk 9: 345-352.

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

Skeel, M.A. and E.P. Mallory. 1996. Whimbrel. No. 219 in Birds of North America series, Birds of North America, Inc, Philadelphia, PA. 28 pp.

Turpie, J.K. and  Hockey, P.A.R. 1997. Adaptive variation the foraging behaviour of grey plover Pluvialis squatarola and whimbrel Numenius phaeopus. Ibis 139(2):289-298.

Velasquez, C.R. and R.A. Navarro. 1993. The influence of water depth and sediment type on the foraging behavior of whimbrels. J. Field Ornithol. 64(2):149-157.