Use of wetland habitats by selected nongame water birds in Maine

Examines the use of 87 palustrine and lacustrine wetlands by nongame water birds. Wetlands used by 15 species of water birds were distinguished from those not used, according to 20 habitats features. The species were common loon Gavia immer, pied-billed grebe Podilymbus podiceps, double-crested cormorant Phalacrocorax auritus, American bittern Botaurus lentiginosus, great blue heron Ardea herodias, green-backed heron Butorides striatus, osprey Pandion haliaetus, bald eagle Haliaeetus leucocephalus, northern harrier Circus cyaneus, Virginia rail Rallus limicola , sora Porzana carolina, spotted sandpiper Actitis macularia, common snipe Gallinago gallinago, herring gull Larus argentatus and belted kingfisher Ceryle alcyon. Smaller, isolated wetlands were used by fewer species than larger wetland in complexes; many species had large area-requirements (pied-billed grebe, common loon, herring gull, double-crested cormorant, bald eagle) or prefered to use wetlands near other wetlands (common loon, herring gull, great blue heron, spotted sandpiper, osprey, bald eagle). Wetland area contributed more to overall variation in species richness on wetlands than wetland isolation, although on small wetlands ≤3.6 ha) isolation was better predictor of species richness than wetland area. Wetlands with intermediate amounts (33-66%) of emergent vegetation supported more species than closed (>66%) or open (<33%) wetlands. Lacustrine wetlands supported a distinct, low diversity community of water birds, including most fish-eating species. Waterbird diversity at forested palustrine wetlands was intermediate between lacustrine communities and more species-rich assemblages at palustrine emergent and scrub-shrub wetlands. -from Authors