Onychoprion aleuticus

Monotypic. Sterna camtschatica Finch, 1882 is a synonym used by some authors, especially in Russian literature (North 1997). Based on similar head patterns, this species may form superspecies with the gray-backed tern (S. lunata) and bridled tern (S. anaethetus); Aleutian and gray-backed tern also have similar foot and bill structure (Cramp 1985). This species formerly (AOU 1983, 1998) was included in the genus Sterna, but it is now placed in Onychoprion on the basis of genetic data that correspond to plumage patterns (Bridge et al. 2005).

The breeding range of Aleutian tern stretches from eastern Russia across the Bering Sea to Alaska. Its non-breeding range stretches across the south Pacific from Sumatra east to Papua New Guinea. The populations have been declining in recent decades, especially in Alaska. There are around 200 breeding sites, although four sites make up 30-50% of the population. The cause of the declines is poorly understood but threats include native predators, storms, extreme high tides, collection of eggs by humans, and climate change.

The breeding range extends from Sakhalin Island, Russia, in the Sea of Okhotsk east to the Gulf of Alaska, United States (Renner et al. 2015). In Alaska, breeding occurs in coastal areas throughout the Aleutian Islands as far west as Attu Island, north to the southeastern Chukchi Sea and east to the Alaska Peninsula, Yakutat, and Glacier Bay (Haney et al. 1991, Renner et al. 2015, Renner et al. 2023). In Asia, breeding is mostly confined to regions in or near the Sea of Okhotsk and western Bering Sea including the Commander Islands, Koraginsky Island, the Kamchatka Peninsula, and Sakhalin Island (Haney et al. 1991, Renner et al. 2015). The breeding range extent is estimated to be approximately 7,000,000 km².

This species spends the non-breeding season in the tropical western Pacific from Sumatra east to Papua New Guinea (Goldstein et al. 2019, Hill and Bishop 1999, Lee 1992, North 2020). The non-breeding range extent is estimated to be approximately 10,000,000 km².

There were 202 active breeding sites in 2012 (Renner et al. 2015).

Like many colony nesting seabirds, storms, extreme high tides, and native predators are the main threats affecting the survival of eggs and chicks (North 2020). Human disturbance can cause an entire breeding colony to abandon the site (Haney et al. 1991). Collecting eggs by humans is an ongoing, but limited threat (North 2020, Renner et al. 2015). In the non-breeding range, threats include human overfishing of prey species, uncontrolled waste disposal, and land-based pollution (Haney et al. 1991). Sea-level rise will likely pose a serious threat to breeding sites.