The Arctic Tern (Sterna paradisaea) is a small, agile seabird in the family Laridae, distinguished in breeding plumage by its entirely blood-red bill, black cap, gray mantle, and deeply forked tail. It breeds on rocky or sandy beaches in the far north and winters in subantarctic and Antarctic waters, making it one of the most widely distributed terns in the world.
Arctic Terns measure 14–17 inches (36–43 cm) in length with a wingspan of 29–33 inches (74–84 cm). Their legs are so short that they appear crouched when standing on the ground. In spring and summer, the entire bill is blood-red, a key feature that separates it from similar species. The tail is deeply forked, with the outer feathers extending into long streamers.
The most common confusion is with the Common Tern (Sterna hirundo). While both are white with black caps and gray mantles, the Arctic Tern has a bill that is wholly red in breeding plumage, whereas the Common Tern’s bill shades to black at the tip. Additionally, the Arctic Tern’s tail is more deeply forked, with a fork depth of about 4.5 inches compared to the Common Tern’s 3.1 inches. In winter, both species have dark bills and feet, making identification more challenging; however, the Arctic Tern’s longer, more deeply forked tail remains a reliable field mark.
Arctic Terns breed circumpolarly on Arctic coasts and inland, from Greenland, Iceland, and the British Isles eastward to Kamchatka, through the Aleutians and Alaska, and across Arctic and subarctic Canada to southeastern Canada. They winter in the subantarctic and Antarctic Ocean, reaching the edge of the pack ice. Outside of breeding, they are found along seacoasts and around interior lakes and marshes.
Arctic Terns are highly sociable and nest in large colonies, which are not always in the same location each year. They are vigorous in defending their nesting sites. On the ground, they walk with a distinctive mouse-like glide. In flight, they are agile and often hover 30–40 feet over the water before diving suddenly to catch prey. This diving behavior, often resulting in complete submersion, is a key behavioral cue for identification.
Courtship involves a “fish flight” display, where the male chases the female through the air while screaming, then offers a small fish. They can even scream with a fish in their mouths. Most Arctic Terns mate for life, reinforcing the importance of stable colony sites.
The Arctic Tern utters a shrill “kee-kee” or “kee-kahr.” These calls are often heard during courtship and colony defense. The energetic nature of the calls, combined with the bird’s agile flight, helps distinguish it from other terns in the field.
Arctic Terns nest in colonies on rocky or sandy beaches in the far north. The nest is usually a simple hollow in sand, gravel, or moss. In June and July, they lay 2–3 brown or greenish eggs with brown speckles. Incubation lasts 21–22 days, and the young fledge about 21–28 days after hatching. Males play a significant role in defending the colony.
Arctic Terns feed on small fishes such as capelin, sand eels, and small crustaceans. They hover over the water on beating wings and then dive suddenly, often completely submerging, to catch their prey. This foraging strategy allows them to exploit a wide range of aquatic habitats.
The Arctic Tern is listed as Least Concern (LC) in the IUCN Red List, as recorded in AviList v2026. However, historical threats include predation by foxes, raccoons, weasels, rats, gulls, and other seabirds. In the past, massive spraying of marshes with insecticides like DDT for mosquito control killed many terns through the consumption of contaminated minnows. Plume hunting in the late 19th and early 20th centuries also decimated populations. While current status is stable, ongoing monitoring is essential to protect breeding colonies from new threats.
When observing Arctic Terns, especially near nesting colonies, maintain a respectful distance. Their vigorous defense of nesting sites means that close approach can cause stress and nest abandonment. Use binoculars or a spotting scope to observe the mouse-like glide and shrill calls from a distance. Focus on the bird’s behavior, such as hovering and diving, rather than attempting to get a close-up view. This approach ensures a positive experience for both the observer and the bird.
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