The common tern, or Sterna hirundo, is a graceful bird that inhabits the coastlines and marshes of North America. Of all the North American terns, it has one of the most widespread distributions on the continent. The bird has a streamlined appearance, a black cap, white collar, and gray body. It is notable for its plunging and diving style of hunting ocean fish, which is a dietary staple for coast-dwelling terns. During the summer, the common tern can be found in southern Canada and the northeast United States. On fall migration, it can be seen throughout the Eastern U.S., and it winters in Central and South America.
A member of a group of black-capped Sterna or tern species, the common tern has a a sleek form with a long forked tail. It is sometimes called a sea swallow because of the shape of its tail and its graceful, nimble flight. Other distinguishing features of the common tern are dark patches on its out feathers, red legs, and red bill with a black tip. This tern can be 12-14 inches (31- 353 cm) in length, and live to an age of 25 years. The bird has various calls including a loud kee-aar sound.
The common tern is usually found near the ocean, where it gets most of its food in the form of fish. Like other terns, its plunge-diving hunting technique involves flying a somewhat short distance above the water's surface, where it might hover to spy a fish before making a rapid plunge. The bird doesn't swim underwater, and emerges with a fish at a success rate found to be one in about three dives. The common tern also feeds on squid and crustaceans and can catch insects in flight.
Being a social bird, the common tern is usually found in flocks or colonies. Flocks of common terns can be seen hunting schools of fish, which can be a clue to fisherman looking for fish. The colonies in which the common tern nest can contain dozens or hundreds of pairs. Colonies can nest in salt marshes or on the coast line, making shallow depressions in the sand as a nest. A mating pair usually produces two or three eggs during the May through August breeding season.
Nearly hunted to extinction in the 19th century for its feathers, the common tern largely recovered during the 20th century. The common tern has since been subject to decline. Human encroachment, marine pollution and the loss of habitat are factors in decreased populations.