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Northern Prairie Wildlife Research Center

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Forest and Rangeland Birds of the United States

Natural History and Habitat Use

Caspian Tern -- Sterna caspia

RANGE: Breeds locally in the West from coastal and eastern Washington, eastern Oregon, northern Utah and northwestern Wyoming south to southern California and western Nevada; in the interior from southern Mackenzie to southern James Bay south to North Dakota, northeastern Illinois, and southern Ontario; at scattered localities along the Atlantic Coast from Newfoundland to South Carolina; and along the Gulf Coast from Texas east to Florida. Nonbreeding birds often summer in the James Bay and Great Lakes region, and along both coasts of the United States. Winters primarily in coastal areas from California and North Carolina south to Mexico.

STATUS: Common.

HABITAT: Usually found near the coastline on sandy, stony, or shell beaches, barrier or spoil islands, islands with sand-gravel substrate with little or no vegetation, or on a shell berm in a salt marsh. Tends to occupy less-developed and less-polluted segments of the coast, but is also found inland along shorelines of large lakes. Wintering terns generally are found along beaches, and on isolated spits, often roosting with other larids. In migration, occurs along water courses or in large marshes.

SPECIAL HABITAT REQUIREMENTS: Sparsely vegetated islets or shorelines.

NEST: Usually found in compact colonies, but occasionally nests singly in the vicinity of other tern species in shallow depressions in the ground on bare sandy or rocky soil.

FOOD: Feeds almost entirely on fish 3 to 10 inches long, foraging on species and sizes that are most readily available; also takes crayfish, insects, nestlings and eggs of other birds, and rarely, carrion.

REFERENCES: Clapp et al. 1983, Johnsgard 1979, Ludwig 1965.

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