Sanderling Habitat Model
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Sanderling, Calidris alba
Use of Study Area Resources:
Migration; in Maine sanderlings are observed primarily at coastal sites (Pierson et al. 1996). They breed in the high Arctic (Johnsgard 1981) and may "undertake among the longest migrations of all birds of the world ... from 50N on the Pacific coast and 35N on the Atlantic coast south to 50S on both coasts" (Myers 1988 in Castro et al. 1992). Shorebirds, including sanderlings, make extensive use of Bay of Fundy and eastern Maine coastal habitats to replenish fat reserves during fall migrations (Hicklin 1987, Dunn et al. 1988).
Sanderlings use sand and mudflats and sandy coastal beaches (Roberts and Evans 1993, Pierson et al. 1996, Degraaf and Rappole 1995). They also make use of algae-covered rocky or muddy shores (Hayman et al. 1986, Terres 1995).
Foraging. "On autumn migration they often feed in wet sand by running quickly and producing a series of closely spaces shallow probes or 'stitches' in the sand, capturing sand flies, small mollusks, ostracods, polychaete worms and the like (Johnsgard 1981)." At stop-over sites during migration, sanderlings are active both day and night, although the highest numbers of birds usually feed in the early morning and late afternoon (Burger and Gochfeld 1992). They spend most of their time in the surf zone, either feeding or roosting (Castro et al. 1992, Burger and Gochfeld 1992, Myers et al. 1990). Some migrants, described as vagrants by Hayman (1986), are found at inland and freshwater sites, occurring in mixed flocks with other 'waders'. Then sanderlings may feed on insects such as midge, mosquito, and cranefly larvae (Johnsgard 1981).
The model 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. These data were supplemented with sites described in Pierson et al. (1996). 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. This buffer distance also was applied to the locations from Pierson et al. (1996).
|Cover Types||Cover Suitability
(0 - 1 scale)
|Upland deciduous forest|
|Upland coniferous forest|
|Upland mixed forest|
|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|
|E1AB||Estuarine subtidal vegetated|
|E1UB||Estuarine subtidal unconsolidated bottom|
|E2AB||Estuarine intertidal algae||0.5|
|E2EM||Estuarine intertidal emergent|
|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|
Habitat Suitability Scoring: Sites with sanderling occurrences and having any of the suitable landcover types (see table) were scored according to level of use and suitability of cover type. If a site had 5 or more birds observed at any time, the level of use = 1.0; else, if any birds were present, or use was expressed as a narrative (Pierson et al. 1996), the level of use = 0.5. The levels of use then were multiplied by the landcover suitability scores (table, above).
Suitable cover types outside of the observation/occurrence polygons were scored as potential foraging habitats; unconsolidated sediment cover types were re-scored 0.2 and rock or algae 0.1.
Burger, J. and M. Gockfeld. 1991. Human activity influence and diurnal and nocturnal foraging of sanderlings (Calidris alba). The Condor 91:259-265.
Castro, G., J.P. Myers, and R.E. Ricklefs. 1992. Ecology and energetics of sanderlings migrating to four latitudes. Ecology 73(3): 833-844.
DeGraaf, R.M. and J.H. Rappole. 1995. Neotropical Migratory Birds: Natural History, Distribution and Population Change. Comstock Publishing Associates, Ithaca, NY. 676 pp.
Dunn, P.O., T.A. May and M. A. McCollough. 1988. Length of stay and fat content of migrant semipalmated sandpipers in eastern Maine. The Condor 90:824-835.
Hayman, P., J. Marchant and T. Prater. 1986. Shorebirds, an Identification Guide. Houghton Mifflin Co., Boston, MA.
Hicklin, P.W. 1987. The migration of shorebirds in the Bay of Fundy. Wilson Bull. 99(4):540-570.
Johnsgard, P.A. 1981. The Plovers, Sandpipers and Snipes of the World. Univ. of Nebraska Press. Lincoln, NE. 493 pp.
Myers, J.P., M. Sallaberry, E. Ortiz, G. Castro, L.M. Gordon, J.L. Raron, C.T. Schick, E. Tabilo, P. Antas and T. Below. 1990. Migration routes of New World sanderlings. The Auk 107:172-180.
Pierson, E.C., J E. Pierson and P.D. Vickery. 1996. A Birders Guide to Maine. Down East Books, Camden, ME.
Roberts, G. and P.R. Evans. 1993. Responses of foraging sanderlings to human approaches. Behaviour 126(1):29-43.
Terres, J.K. 1995. The Audubon Society Encyclopedia of North American Birds. Wings Books, Avenel, NJ 1109 pp.