Northern Prairie Wildlife Research Center
HABITAT: From boreal regions to temperate prairies, inhabits small to moderately sized rocky islands and occasionally peninsulas in large freshwater lakes, rivers, or ponds (a few colonies are on oceanic islands or coasts). Usually avoids densely settled areas. Outside the breeding season, frequents harbors, refuse dumps, sewage outlets, reservoirs, lakes, ponds, streams, coastal bays, estuaries, beaches, and mudflats. Roosts on exposed sandbars and islands.
SPECIAL HABITAT REQUIREMENTS: Islands and peninsulas covered with low vegetation 6 to 54 inches high.
NEST: Frequently nests in mixed colonies with other Laridae, including herring and California gulls. Usually nests on the ground in flat, elevated, sparsely vegetated areas, but sometimes in low trees.
FOOD: Forages in plowed fields, pastures, tidal flats in salt marshes, along the shore, along beaches, and in shallow waters. During the breeding season, feeds extensively on insects, grains, and small fishes. Also eats small rodents, earthworms, and refuse.
REFERENCES: Clapp et al. 1983, Cramp and Simmons 1983, Jarvis and Southern 1976, Vermeer 1970.