Common Tern

The Common Tern is a graceful, medium-sized tern that breeds widely across the Northern Hemisphere, familiar along coasts, lakes, and rivers. Breeding adults show a crisp black cap, pale gray upperparts, whitish underparts, and a red-orange bill tipped with black, along with red legs.

The tail is deeply forked, giving rise to the old nickname "sea swallow," and the wings show a dark wedge on the outer primaries that becomes more pronounced as the summer progresses due to feather wear. In non-breeding plumage, the forehead turns white and the bill darkens.

Common Terns nest in colonies on sandy or gravelly beaches, islands, and sometimes specially constructed nesting platforms, and are strongly migratory, wintering along tropical and subtropical coasts far to the south.

Key field marks

• Black cap in breeding plumage
• Red-orange bill with a black tip
• Red legs
• Deeply forked tail ("sea swallow")
• Dark wedge on the outer primaries visible in flight

Similar species

• Arctic Tern: shorter legs, all-red bill without a black tip in breeding plumage, longer tail streamers, and grayer underparts.
• Forster's Tern: paler, silvery primaries rather than a dark wedge, and orange legs.
• Roseate Tern: paler overall with a mostly black bill and very long tail streamers.

Habitat

Breeds on sandy or gravelly beaches, offshore islands, salt marsh islands, and inland lakes and rivers; forages over open water near the coast or on large lakes.

Range and migration

Breeds across a broad swath of North America, Europe, and Asia. A strongly migratory species, wintering along tropical and subtropical coasts of Central and South America, Africa, and southern Asia, undertaking long transoceanic journeys.

Behavior

Common Terns forage by hovering over water and plunge-diving for fish, and are highly social, nesting in dense colonies and mobbing predators and intruders that approach the nesting area.

Voice

Calls include a harsh, grating "kee-arrr" and a sharper "kip" note, given frequently at colonies and while foraging.

Feeding

Feeds mainly on small fish caught by plunge-diving from several meters above the water, supplemented by crustaceans and other invertebrates.

Nesting and breeding

Nests colonially on open sand, gravel, or rock, building a simple scrape sometimes lined with vegetation or debris. Clutches typically contain two to three eggs, incubated by both parents for about three weeks; chicks are cared for by both parents until fledging.