Aleutian Tern

During breeding season, the colonies gather along Pacific coastlines of Alaska and Russia. More precisely, breeding colonies have been located along the coast of Chukchi Sea (western Alaska), on the Seward Peninsula and Yukon-Kuskokwim River Delta along the Alaska Peninsula, in the Aleutian Island, in the Kodiak Archipelago, on the Kenai Peninsula and Copper River delta, and along the Gulf of Alaska. The current worldwide minimum breeding population has been estimated at approximately 31 000 birds, with most colonies occurring in the Siberian region of Russia (25 602 birds in 89 colonies) and the remaining 18% occurring in Alaska (5 529 birds in 111 colonies). However, within the last decade, there have been reports of colony declines and disappearances at individual sites in Alaska. This species is strongly migratory, and although the wintering range is poorly known, it is believed to lie off Indonesia and Malaysia. Small flocks of the species have been increasingly sighted in coastal areas around Hong Kong in spring and fall, around Singapore and Indonesia between October and April, and in coastal waters of Java, Bali and Sulawesi during December. The regular appearance of Aleutian terns in fall off Hong Kong suggests one possible route for southbound migrants. The Aleutian tern stands out from its congeners because it is the only species to show an annual migratory behaviour between a subarctic breeding zone and tropical wintering areas in the South Pacific. Only a very small number of Charadriiformes breeding in Alaska appear to have a connection to East Asia.

The Aleutian tern has been designated as a species of concern by several agencies and NGOs (Alaska Department of Fish and Game, Audubon Alaska, U.S. Fish and Wildlife Service, The North American Waterbird Conservation Plan). In 2007, an Aleutian tern Working Group was organized in Alaska in order to examine the necessity to develop an accurate population estimation method and therefore prioritizing the management of the species and the identification of its migration pathway. In 2010, they began to deploy geolocators on Aleutians terns from colonies in Alaska. The lack of data on breeding biology and ecological behaviours limits the development of conservation actions for the species. Further research should focus on the monitoring of populations and colonies in Alaska, Russia and South Pacific regions and the understanding of the main causes of the recent decline of the species.