How to Identify Arctic Tern Feathers

What Arctic Tern Feathers Look Like

The Arctic Tern is a slender, graceful seabird famous for the longest migration of any animal, and its feathers are built for endurance flight. Upperparts are pale gray, underparts (in breeding plumage) can show a light gray wash, and the crown is capped in solid black. The tail is long and deeply forked, forming the classic "swallow-tailed" streamers used to separate terns from gulls at a glance - these streamer feathers are mostly white with pale gray outer webs. The most useful diagnostic feature is on the outer primaries: Arctic Tern's flight feathers are pale gray with only a very narrow, thin dark trailing edge, so the wingtip often looks almost translucent when backlit, lacking the broader, more solidly dark wedge seen on the primaries of the very similar Common Tern.

Step-by-Step: Is This Feather From an Arctic Tern?

• Check the primary trailing edge. A narrow, thin dark line along the tip/trailing edge of an otherwise pale gray primary, rather than a broad dark wedge, favors Arctic Tern.
• Hold the feather to the light. Arctic Tern primaries often look somewhat translucent near the tip due to their thin dark margin; Common Tern primaries look more solidly opaque and dark-tipped.
• Measure the tail streamers. Longer, more attenuated outer tail feathers suggest Arctic Tern, which has proportionally longer streamers than Common Tern.
• Note overall feather paleness. Arctic Tern tends to run slightly paler gray overall on the upperparts/wing than Common Tern.
• Consider location and season. Feathers found on Arctic or subarctic tundra coastlines in summer are far more likely Arctic Tern than Common Tern, which favors more temperate coasts.

Similar Species & How to Tell Them Apart

• Common Tern: The closest look-alike; shows a broader, darker wedge on the outer primaries and shorter tail streamers than Arctic Tern.
• Forster's Tern (in non-breeding areas): Shows a distinctly pale, frosty appearance to the outer primaries with a different pattern of dark markings, and paler overall tail.
• Roseate Tern: Very long tail streamers similar to Arctic Tern, but the wing lacks the same dark trailing-edge pattern and the body plumage is whiter overall.

Where & When You'll Find Them

Arctic Terns breed on Arctic and subarctic tundra coastlines and islands across the Northern Hemisphere in summer, then undertake an extraordinary migration to spend the Southern Hemisphere summer in Antarctic waters - meaning they experience more daylight than any other animal on the planet. Because so much of their life is spent at sea or on remote breeding grounds, most of their molt happens away from easily accessible areas; the best opportunity to find feathers is at breeding colonies on rocky coasts and tundra during the brief Arctic summer breeding season.