Purple Sandpiper Habitat Model
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Purple sandpiper, Calidris maritima
Use of Study Area Resources:
Migration and wintering; purple sandpiper breeding is circumpolar, subarctic and arctic. They winter on the Atlantic coast of Europe, and North America as far south as Florida (Johnsgard 1981, Terres 1995).
Wintering and migrating purple sandpipers forage on rocky intertidal areas, jetties, at the edge of surf on seaweed covered rocks (Hayman et al. 1986, National Geographic Society 1983, Helmers 1992, Pierson et al. 1996). They forage diurnally and nocturnally, roosting at high tide when the shoreline is covered (Summers 1994). Foods include gastropod mollusks, amphipod crustaceans, small fishes, and insects (Johnsgard 1981). Purple sandpipers frequent exposed sea coast, rarely feeding on sandy or muddy beaches unless there are rocky areas nearby (Hayman et al. 1986, Bull 1964 in Terres 1995).
Our habitat mapping 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||1.0|
|E2EM||Estuarine intertidal emergent|
|E2RS, R1RS||Estuarine, tidal river rocky shore||1.0|
|E2SS||Estuarine intertidal shrub|
|E2US, R1US||Estuarine, riverine intertidal unconsolidated shore|
|M1AB||Marine subtidal vegetated|
|M1UB||Marine subtidal unconsolidated bottom|
|M2AB||Marine intertidal algae||1.0|
|M2RS||Marine intertidal rocky shore||1.0|
|M2US||Marine intertidal unconsolidated shore|
Habitat Suitability Scoring: Sites with purple sandpiper occurrences and having any of the suitable landcover types (see table) 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, or use was expressed as a narrative (Pierson et al. 1996), the suitability index = 0.5.
Suitable cover types outside of the observation/occurrence polygons were scored 0.2, as potential foraging habitats.
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.
Helmers, D.L. 1992. Shorebird Management Manual. Western Hemisphere Shorebird Reserve Network, Manomet, MA. 58 pp.
Johnsgard, P.A. 1981. The Plovers, Sandpipers and Snipes of the World. University of Nebraska Press. Lincoln, NE. 493 pp.
National Geographic Society. 1983. Field Guide to the Birds of North America. National Geographic Society, Washington, D.C.
Pierson, E.C., J E. Pierson and P.D. Vickery. 1996. A Birders Guide to Maine. Down East Books, Camden ,ME.
Summers, R. 1994. Diurnal and nocturnal activities of a purple sandpiper, Calidris maritima. Wader Study Group Bulletin 72:33-34.
Terres, J.K. 1995. The Audubon Society Encyclopedia of North American Birds. Wings Books, Avenel, NJ.