One of several small white terns that do not attain full adult alternate plumage until at least their third summer (three years after hatch year), this species is slightly smaller, shorter-legged, and shorter-billed than similar Common, Forster's and Roseate terns. Alternate adult has gray back and wings, paler gray underparts, long forked tail, white face, black cap and nape, thin red bill, and short red legs. Second summer birds (Alternate I) usually show some white on the forehead instead of a completely black crown, but are otherwise near identical to Alternate Adult. Basic Adult shows nearly uniform pale gray back and upper wing surface with a faint black smudge on shoulder (Iess conspicuous than Common Tern), white underparts, mostly white face and forehead with a black mask through eye that connects across the nape and hind crown, black bill and legs. First Basic plumage, is retained through the first summer, thus basic-plumaged birds seen in North America during summer (this is rare) are presumed to be in their second year of life. Unlike Common Terns, which retain 4-5 outer primaries from juvenile plumage, Arctic Terns replace all primaries during their first prebasic molt, so there is no difference in wear or coloration between the inner and outer primaries. Juvenile is lightly scalloped on back with faint brown tones and has orange legs. In all plumages sexes are similar. In flight, note small-headed, short-necked profile, with limited head/neck extension in front of evenly gray-toned wings. Common Tern is similar, with longer bill and legs and darker wingtips.

Length: 30 (cm) Wingspan: 78 (cm)

Voice:

Rasping, harsh, squeaky notes, generally higher-pitched than Common Tern.

Habitat:

Nests on islands and tundra, migrates and winters on open ocean.

Behavior:

Breeds colonially; nest is a scrape or platform of vegetation on the ground. Arctic Terns have the longest known migration of any animal, flying roughly 24,000 miles each year from the Arctic to the Antarctic and back. Basic-plumage first summer birds rarely come north to breeding grounds, instead remaining on or near wintering grounds off of South America.

Feeding:

Plunge-dives into water or picks food off water's surface; eats fish and other small aquatic organisms.