Common Tern

Upperparts pale grey, underparts white to pale grey. Distinctive black cap extending below the eyes and to the nape. Deeply forked tail with dark outer webs on the streamers.

White forehead, black cap restricted to the back of the head. Bill is predominantly black. A dark carpal bar is visible on the leading edge of the wing.

Upperparts with brownish scaly pattern, forehead whitish to buff. Dark carpal bar prominent. Bill base often orange-brownish.

No pronounced sexual dimorphism; males and females are virtually indistinguishable by plumage.

Red bill with a black tip (breeding plumage), red legs. In flight, the outer primaries show a dark wedge. Tail streamers are shorter than those of the Arctic Tern (Sterna paradisaea).

Arctic Tern (Sterna paradisaea - longer streamers, all-red bill), Sandwich Tern (Thalasseus sandvicensis - larger, black bill with yellow tip).

Straight and pointed. In breeding plumage, bright red with a sharply defined black tip. In non-breeding plumage, almost entirely black.

No true song; courtship calls consist of rhythmic sequences of 'kik' notes.

Most common call is a descending, harsh 'kierrr' or 'krree-arr'. When agitated, a short, sharp 'kik-kik-kik'.

Holarctic distribution; inhabits Europe, North Asia, and North America from temperate to subarctic zones.

Long-distance migrant; winters along the coasts of West and South Africa, South America, Southern Asia, and Australia.

Migrates along coastlines but also on a broad front overland. European populations primarily migrate to West Africa.

Coasts with sandy and shingle beaches, islands, inland on unregulated rivers with gravel bars, lakes, and artificial nesting rafts.

Shallow coastal waters, estuaries, lagoons, inland rivers, and fish-rich lakes.

Shallow scrape in the ground (sand, gravel, or short turf), sparsely lined with bents, shell fragments, or small stones.

Creamy to olive-brown with irregular dark spots and blotches for camouflage against the substrate.

Both parents incubate and feed the chicks. Young are semi-precocial and continue to be cared for weeks after fledging.

Primarily small fish (e.g., sand eels, herring, sticklebacks), occasionally crustaceans and insects (dragonflies, beetles).

Predominantly small marine fish and marine invertebrates.

Plunge-diving from hovering or gliding flight, usually from heights of 5 to 10 meters.

Visual search for prey just below the water surface; often foraging in groups at fish-rich locations.

Highly social; breeds almost exclusively in colonies and migrates in flocks.

Communal defense of the colony against predators (mobbing), group foraging, and synchronized migration.

Loss of natural breeding habitats due to river regulation, predation (e.g., by brown rats, mink, herring gulls), disturbance from recreational activities, and flooding events.

Stable to decreasing; locally stabilized in Central Europe due to conservation measures, but remains dependent on habitat management.

Protection and management of breeding colonies, designation of protected areas, provision of artificial nesting rafts, predator management, and visitor guidance.