Common Tern

Overview

The common tern (Sterna hirundo) is a seabird in the family Laridae with a circumpolar distribution, breeding in temperate and subarctic regions of Europe, Asia, and North America. It is a strongly migratory species that winters in coastal tropical and subtropical regions. Despite its large population and wide breeding range, numbers in North America have declined sharply in recent decades.

Identification

• Breeding adults have pale grey upperparts, very pale grey underparts, a black cap, and orange-red legs.
• The narrow pointed bill is mostly red with a black tip or all black, depending on the subspecies.
• The nominate subspecies measures 31–35 cm in length with a 77–98 cm wingspan.
• The most distinctive vocalisation is the alarm call KEE-yah, stressed on the first syllable, which contrasts with the second-syllable stress of the similar Arctic tern.

Habitat

Breeding in a wider range of habitats than any of its relatives, the common tern nests on any flat, poorly vegetated surface close to water, including beaches, islands, and artificial substrates such as floating rafts. Its breeding range covers temperate and subarctic zones of Europe, Asia, and North America, while it winters in tropical and subtropical coastal areas.

Diet

The common tern feeds by plunge-diving for fish in both sea and freshwater environments. Molluscs, crustaceans, and other invertebrate prey may also form a significant part of the diet in some areas.

Did you know?

Females select mates based on the quality of their wing feathers, which indicates fitness through the greater ultraviolet reflectance of new primaries.