Aleutian Tern

Identification

The Aleutian tern is a medium-sized tern measuring 32–39 cm in length with a 75–80 cm wingspan, weighing 84–140 g. Its most distinctive feature is a white forehead contrasting with a black cap, which immediately separates it from the closely resembling Arctic tern (whose breeding adults have bright red bills, feet, and legs). The Aleutian tern has entirely black bill and legs. The breeding plumage shows a mid-grey mantle with darkish grey underparts, white rump and tail, and a diagnostic dark bar on the wing secondaries. Juveniles display extensive white on the forehead and underparts with a grey tail. Non-breeding adults retain the dark secondary bar year-round, though the white forehead becomes less distinct.

The Aleutian tern's calls are higher-pitched and softer than those of related species, with a distinctive rolling whistled tone. The most characteristic call is a choppy "chif-chif-chu-ak," along with a prolonged "whee-hee-hee-hee" stressed on the first syllable. The bird remains largely silent while incubating.