21-6-2017 RACO DE OLLA, VALENCIA - COMMON TERN (Sterna hirundo)

Common Terns are found nesting on flat, poorly vegetated surfaces close to water, such as beaches, islands, and artificial substrates like floating rafts. They adapt to a variety of habitats, from the taiga to tropical shores, and avoid excessively rainy, windy, or icy areas.

This species has a wide breeding range, encompassing Europe, North Africa, Asia, and North America. It migrates to winter along the coasts of Central and South America, Africa, and southern Asia, with some populations remaining partially migratory in the Caribbean.

Common Terns are agile flyers, capable of rapid turns, hovering, and vertical take-off. They are known for their powerful, direct flight and can fly at speeds averaging 30 km/h, increasing during migration. They breed in colonies, often alongside other seabird species, and exhibit strong territorial behavior.

The Common Tern has a distinctive alarm call, a KEE-yah, and a repertoire of other vocalizations used for communication within the colony and with their chicks. Parents and chicks recognize each other's calls, aiding in maintaining family bonds.

Breeding involves aerial courtship displays and ground rituals. Nests are shallow scrapes, sometimes lined with debris. Clutch size is typically three eggs, camouflaged with blotchy patterns. Both sexes incubate, and chicks fledge in 22–28 days. Adults are defensive of their nest and young, often harassing intruders.

The Common Tern can be confused with the Arctic Tern, Roseate Tern, and Forster's Tern, but differences in plumage details, leg and bill color, and vocalizations aid in distinguishing them.

The diet consists mainly of fish, which they catch by plunge-diving, but may also include molluscs, crustaceans, and large insects. They forage up to 15 km from the breeding colony and may follow schools of fish or predatory fish to locate prey.

The Common Tern is classified as Least Concern, with a large population and extensive breeding range. However, threats such as habitat loss, pollution, and disturbance have led to declines in some areas, particularly in North America. Conservation efforts include habitat management and protection from human disturbance.