Arctic Tern

The Arctic Tern is a slim, elegant seabird renowned above all for its extraordinary migration, traveling annually between Arctic breeding grounds and the edge of Antarctic pack ice, a round trip that can exceed 70,000 kilometers (43,000 miles) and represents the longest migration known in the animal kingdom.

In breeding plumage, it closely resembles the Common Tern but is slightly more compact, with shorter, blood-red legs, a bill that is entirely deep red without a black tip, and a grayer wash to the underparts that contrasts with a white cheek stripe. The tail streamers tend to be longer than those of the Common Tern, and the wings appear more translucent in flight due to thinner primary feathers.

Thanks to its pole-to-pole migration, an Arctic Tern may experience more daylight over its lifetime than any other creature on Earth, following summer from one hemisphere to the other.

Key field marks

• Entirely deep red bill (no black tip) in breeding plumage
• Short, blood-red legs
• Grayer underparts with a contrasting white cheek stripe
• Long tail streamers
• Translucent-looking primaries in flight

Similar species

• Common Tern: longer legs, bill typically red-orange with a black tip, less contrast between cheek and underparts, and a dark wedge in the outer primaries.
• Forster's Tern: paler, silvery wingtips and orange (not red) legs and bill base.

Habitat

Breeds on Arctic and subarctic coasts, tundra, and rocky islands. Outside the breeding season it is almost entirely pelagic, spending months over the open ocean.

Range and migration

Breeds around the Arctic and subarctic, including northern North America, Greenland, Iceland, and northern Eurasia. Undertakes an extraordinary migration to winter in the productive waters near the edge of the Antarctic pack ice, effectively experiencing two summers each year.

Behavior

Arctic Terns are famously aggressive in defense of their nests, diving and striking at intruders, including humans, that approach too closely to the colony.

Voice

Calls are similar to the Common Tern, including a harsh "kee-arr" and sharper alarm notes, though generally slightly higher-pitched.

Feeding

Feeds mainly on small fish and crustaceans, caught by hovering and plunge-diving, often close to the surface in cold Arctic and subarctic waters.

Nesting and breeding

Nests colonially on open ground near water, often on gravel beaches or rocky islands, in a simple scrape. Clutches typically contain one to three eggs, incubated by both parents for about three weeks.