By Robin Street
Geographic Range
Circumpolar; nests on Northern European islands and peninsulas from Iceland to Northern Russia/Siberia, British Isles, Netherlands, Denmark, Sweden, the Baltic Nations, Northern Alaska, extreme of Northern Canada, Greenland, Newfoundland, and south along Atlantic Coast to Massachussetts; winters in S. Hemisphere in subantarctic and Antarctic waters of Atlantic, Pacific, and Indian Oceans.
Biogeographic Regions:
nearctic 
(native ); palearctic (native ).
Habitat
All terns live along seacoasts and around interior lakes and marshes.
Aquatic Biomes:
lakes and ponds; coastal .
Physical Description
Arctic terns are 14-17''(36-43 cm) long with a wingspread of 29-33''(74-84 cm). They are white with black caps and gray mantles, and a deeply-forked tail. In spring and summer, the entire bill is blood-red. Their legs are so short that the birds appear to be crouched when standing.
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
They nest in colonies defended by the males in the rocky or sandy beaches of the far north. The nest usually consists of a hollow in sand, gravel or moss. In June-July, 2-3 brown or greenish eggs with brown speckles are incubated for 21-22 days. Young fly about 21-28 days after hatching
Key reproductive features:
iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
Behavior
Arctic terns walk with a mouse-like glide and utter a shrill "kee-kee" or "kee-kahr". Many migrate from the Arctic summer breeding grounds to Antarctica for a "second summer", making them the animal that sees the most sun. Terns are very sociable and nest in large colonies, which are not always in the same area each year. They are vigorous in defending their nesting colonies and are most successful in breeding when they nest close together. Tern courtship is performed through a "fish flight" by the male: after much aerial chasing and screaming, the male offers a small fish to the female. They can even scream with a fish in their mouths. Most terns mate for life.
Key behaviors:
flies; motile .
Food Habits
Arctic terns hover 30-40 feet over the water on beating wings and then dive suddenly into the water with a splash, often completely submerging to catch small fishes such as capelin, sand launae, sand eel, and small crustaceans.
Economic Importance for Humans: Positive
Once hunted for their feathers.
Conservation Status
IUCN Red List: [link]:
Least Concern.
US Migratory Bird Act: [link]:
Protected.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
No special status.
Foxes, raccoons, weasels, rats, gulls, and other seabirds are all predators of terns and their eggs. Massive spraying of marshes with insecticides (DDT) for mosquito control has killed many terns through their consumption of DDT-laden minnows. In the last decade of the 19th century and in the first decade of the present one, plume hunters killed tens of thousands of terns for their plumage for women's hats.
Contributors
Robin Street (author), University of Michigan.
