The Elusive Aleutian Tern
Aleutian Terns are of special interest because we know very little about them and their breeding range is limited to Alaska and Eastern Siberia. They nest on the outer coast of Alaska from Glacier Bay to Barrow. They are by all accounts a rare bird, with a global population estimated at approximately 30,000 individuals. The breeding population estimate for Alaska is 5,500 birds.
An Aleutian Tern in flight.
Aleutian terns have a distinct white triangular patch on their forehead just above the bill. They also have black feet, legs, and bill. Aleutian Terns are similar in size to Arctic Terns, but stouter with a more deeply forked tail. Perhaps the biggest contrast between Aleutian and other tern species is in their call. Instead of a harsh cry, Aleutian Terns emit a musical whistling sound similar to a shore bird. Aleutian Terns are also much less aggressive in defending their nesting colonies; instead of dive bombing, they will generally hover high over the colony when disturbed by humans.
Besides limited colony counts, very little is known about the breeding ecology of this species, and information on their migration routes and wintering areas is only recently coming to light. This species is designated as a species of concern by several agencies and conservation organizations, primarily due to suspected population declines throughout their range. A dedicated group of researchers and managers are collaborating to learn more about this species including population status and trend, risks to the population as a whole, and potential future conservation actions.
A researcher is reminded that the Aleutian Tern does not take kindly to humans during a bird banding event.
An Aleutian Tern perches on a log.
Scientists Are Racing to Understand the Aleutian Tern’s Mysterious Decline.
“In general, there’s fewer numbers,” Oehlers says. In the 1980s, biologists counted 3,000 Aleutian Terns on Black Sand Spit, but in 2020, the count dropped to approximately 1,100 individuals. And in 2021, Oehlers and her crew counted only 242 terns. But the biologists aren’t certain if the terns have died off, or are just relocating to unknown colonies.