Forster's Tern (Sterna forsteri)

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A Field Guide to Eastern Birds. by Roger Tory Peterson.

Return to Eastern Gulls and Terns

Summer (top) and Winter (bottom)

Color Photograph: © by and courtesy of John Cassady

Winter

Color Photograph: © by and courtesy of Robert Benson

Forster's Tern (Sterna forsteri)

Identification: Length from tip of bill to tip of tail 14 to 15 inches.

Adult Summer Plumage: Upper half of head and back of neck black. Lower half of face white. Bill yellowish-red with a black tip. Breast and undersides white to light gray. Wings gray with the primary feathers dark gray and heavily accented with white. Tail y-shaped. Legs red, normal in length for a tern.

Adult Winter Plumage: Similar to the summer plumage, but crown of head white, not black. A distinct black band stretches from the eye to the back of the head. Bill almost all black.

Immature: Similar to the adult winter plumage.

Similar Species:  Forster's Tern is easily confused with the Common Tern. The bill of Forster's Tern is more orange than red. The primary wing feathers of Forster's Tern are dark gray, heavily accented with white. In contrast the primary wing feathers of the Common Tern are gray or gray suffused with dull black. The Common Tern prefers ocean beaches as breeding grounds. In contrast Forster's Tern breeds in freshwater and salt marshes. The breeding grounds of the Arctic Tern are far north of those of Forster's Tern. The Arctic Terns has a solid red bill and lacks the heavy white accenting of the primary wing feathers.

Breeding Range (see map below): Forster's Tern has an unusual distribution with the largest part of its range in the south-central and north-central prairie regions of Canada and the United States extending into the western United States and Great Lakes. The species also breeds and is resident all year along the Atlantic and Gulf Coasts of the United States.

Overwintering Range:  This species overwinters along the Atlantic and Gulf Coasts of the United States as well as along the California Coast.

Habitat: Forster's Tern breeds and overwinters in freshwater marshes, salt marshes, and prairie sloughs.

Food: Mostly small fish, but also some aquatic insects and marine invertebrates.

Behavior: Forster's Tern, although similar to the Common Tern and Arctic Tern, is found in a marsh habitat completely different than the coastal or tundra ranges of these two species. The voice is a coarse beep.

Reproduction:  The clutch consists of 3 to 4 brown-spotted tan eggs. The eggs are typically laid on a platform of grasses lined with finer plant material. The nest is usually placed among masses of dead marsh plants. The species nests in colonies.