The Aleutian tern (Onychoprion aleuticus) is a migratory bird living in the subarctic region of the globe most of the year. It is frequently associated with the Arctic tern, which it closely resembles. While both species have a black cap, the Aleutian tern may be distinguished by its white forehead (although juvenile Arctic terns also have white foreheads). During breeding season, the Arctic terns have bright red bills, feet, and legs while those of the Aleutian terns are black.
Onychoprion aleuticus has not been thoroughly studied yet. If its winter migratory range was completely unknown until the late 1980s; it is now known that many Aleutian terns spend the winter near the Equator in the western Pacific. The Aleutian tern breeds in wide-ranging coastal colonies only in Alaska and eastern Siberia. Although Alaskan and Siberian populations are not well monitored, both are thought to be in significant decline.