Sterna forsteri
(Forster's Tern)

Physical Description:
14-16 1/4" (36-41 cm). A slender, graceful, gull-like bird with a black cap, long, pointed wings; and a deeply forked tail. Breeding adults have pale gray back and wings with frosty tips, whitish primaries, and gray tail. Bright orange-red bill with black tip; legs orange. Winter adults and immatures only have black patch around eye; bill black.

Similar Species- Common Tern, Arctic Tern

Song:
A harsh, nasal aaaap; a low, nasal kyarr; a buzzy zraa; and a high-pitched kyer.

Distribution:
Breeds from central Prairie Provinces of Canada, south to southern California, western Nevada, southern Idaho, northern Utah, northern and eastern Colorado, and portions of Midwest. Also breeds along portions of Gulf and Atlantic coasts. Winters from central California and Baja California, south to Central America, and from northern Mexico to portions of Gulf and East coasts.

Habitat:
Found on freshwater and salt marshes. During migration and in winter, also found on seacoasts, bays, estuaries, rivers, and lakes.

Diet:
Eats insects and fishes.

Ecology:
When not breeding, found singly or in small, loose groups. Frequently nests in loose colonies; vigorously defends nest. In Idaho, average colony size is small -- 8.1 nests. Builds platform nest on water, or may nest independently on ground or sand. Intolerant of other birds, but American Coot may parasitize nest. Snatches food off surface of water while in flight, or dives into water.

Reproduction:
Both sexes incubate 3- 4 eggs for about 23-24 days. Nestlings are semi-precocial and downy. Young are tended by both adults until capable of flight.

Conservation:

Element Code:	ABNNM08090
Status:	Protected nongame species
Global Rank:	G5
State Rank:	S2
National Rank:	N5B,N5N

Important State References:
Trost, C.H. 1994. Status and distribution of colonial waterbirds in northern Idaho and selected species in southern Idaho, 1994. Dept. Biol. Sciences, Idaho St. Univ., Pocatello. 31pp.