Least Sandpiper Habitat Model
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Draft Date:
June 2001

Species:
Least sandpiper, Calidris minutilla

Habitat Type:
Migratory; in the study area they are found at coastal and some inland sites (Pierson et al. 1996). Least sandpipers breed in the subarctic tundra and boreal forest of North America, as well as coastal habitats in Nova Scotia (Cooper 1994). An isolated nesting was reported on Monomoy Island, Massachusetts (Anderson 1980). Least sandpipers winter across the southern U.S. and broadly through the northern half of South America (Cooper 1994). They may undertake non-stop migrations of thousands of miles, relying on key staging areas to replenish energy reserves.

Cover Types:
On migration least sandpipers roost in salt marshes and wet meadows near foraging areas (Cooper 1994); the latter include open coasts and mudflats (Hayman et al. 1986). On broad coastal mudflats they use dendritic channels; on rocky shorelines the edges of tide pools (Cooper 1994). They forage on higher portions of the flats and intertidal habitats than congeners, rarely in water more than 2-4 cm deep (Cooper 1994). They are found less frequently than their congeners on sandy beaches (Degraaf and Rappole 1995). Least sandpipers use inland areas during migration more often than most shorebirds; these include muddy margins of lakes, ponds, sloughs, ditches, marshes, wet meadows, or flooded agricultural fields (Cooper 1994, Degraaf and Rappole 1995). Prey is predominantly amphipod crustaceans in coastal areas, and small insects (chironomids, dipterans, and isopods) in interior areas (Cooper 1994).

Migratory behavior is poorly known, but they occur in flocks ranging from “dozens to hundreds, occasionally thousands, at key staging sites”, staying for longer periods in the fall than in the spring (Cooper 1994).

Model:
The habitat models relied on abundance/occurrence information from a Maine Department of Inland Fisheries and Wildlife (MDIFW) shorebird coverage, the Manomet Bird Observatory's International Shorebird Survey (ISS) database for Massachusetts and New Hampshire, and inland sites used by least sandpipers in Maine (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, and Pierson et al.'s (1996) observations also were somewhat general, 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
Upland scrub/shrub
Cultivated
Developed
Bare ground
PEM, L2EM Lake/pond, emergent vegetation 0.5*
PFOcon Palustrine forest, conifer
PFOdec Palustrine forest, deciduous
PSSdec Palustrine scrub shrub, deciduous
PSScon Palustrine scrub shrub, conifer
PAB, L2AB Lake/pond, aquatic vegetation 0.5*
L1UB, PUB Lake/pond, unconsolidated bottom 0.5*
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
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
M2RS Marine intertidal rocky shore 0.5
M2US Marine intertidal unconsolidated shore 1.0
NOTES *included only if within 1 km of known site with regular draw-downs

Habitat Suitability Scoring: Sites with least sandpiper 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, or use was expressed as a narrative (Pierson et al. 1996) the suitability index = 0.5. This value was then 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 rescored 0.2, rocky and marsh types rescored 0.1.

Sources:
Cooper, J.M. 1994. Least Sandpiper (Calidris minutilla). In A. Poole and F. Gill (eds.) The Birds of North America, No. 115. The Birds of North America, Inc., Philadelphia, PA.

DeGraaf, R.M. and J.H. Rappole. 1995. Neotropical Migratory Birds: Natural History, Distribution and Population Change. Comstock Publishing Associates, Ithaca, NY. 676 pp.

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.

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