The Aleutian tern is a small, elegant tern with short legs, long wings that project beyond the tip of the tail tail, and a spiky bill. In breeding plumage, it has dark silvery-grey upperparts, and paler grey underparts, with a white rump and tail. On the head, the forehead, cheeks, and throat are white, there is a black eyestripe, and a black cap. The bill and legs are black. Not much is known about Aleutian terns out of breeding season, but they have been described as looking the same, but with a patch of white between the eye and bill. Males and females are similar.
It has a soft, trilled call, which is different from most other terns which tend to be harsh and grating. It is a poor swimmer due to its short legs and small webs.
Aleutian terns eat mainly fish, crustaceans, and zooplankton. It forages in shallow water, usually flying above the surface before swooping down to pick prey from the surface, but will also dive to shallow depths, or sit on the surface of the water and feed by surface-dipping.
They will also occasionally catch insects in flight over freshwater ponds and meadows.
During breeding season, Aleutian terns are found on the coast of southern and western Alaska, eastern Siberia and around the Aleutian Islands. They form colonies on vegetated islands, tundra, grass, and sedge meadows.
In winter they migrate to the warm, tropical waters of the Pacific Ocean around south east Asia including the Philippines, Indonesia, and Malaysia, although the exact range is not known.