Length 34–39 cm, wingspan 70–80 cm, weight 90–150 g. Life expectancy: 25 years.
Adult: Common Terns have white underparts and pale grey back and wings. They have conspicuous black caps, and some darker colouring on the trailing edge of the tips of their primary wing feathers. They closely resemble Arctic Terns, but can be distinguished by the black tip to their beak, their longer legs, broader and only slightly transparent wings, and more stable flight. Their white tails are deeply forked.
Juvenile: Common Terns have slightly darker grey backs (with some brown and white edges to their feathers) and darker colouring visible on the leading edge of their secondary wing feathers. Their foreheads are mainly white and their black caps only begin behind their eyes. Common Terns’ legs are red (adults) or orange (juveniles), their beaks are red with a black tip (adults) or dark brown with a yellowish base (juveniles), and their irises are dark.
He makes shrieking screams “ki-ya” or “ki-ki-ki.”
Distribution and Habitat
Holarctic species with breeding area, which covers Europe (excluding Portugal), Asia, Siberia, North America, Caribbean. Winters in Africa. Spring migration is in April, and autumn – in October.
It inhabits freshwater, brackish and super-salted natural and artificial wetlands.
In Bulgaria Common Tern is a nesting and passing species. The main population since the 1980s is concentrated in the Bourgas Wetlands where nests on artificial islands and platforms. It now breeds in 13 fields, most important of which are Atanasovsko Lake, Pomorie Lake, Poda Protected Site, Snake Island, the Ropotamo River, islands and marshes of the Danube and some of the larger inland rivers.
Common Tern feeds on insects, invertebrates and fish. He often hunts by hanging in the air and diving into the water by diving, or in flight catches insects and fish from the water surface.
It breeds in isolated or mixed colonies with the Little White-Eyed Tern, the Brown-Tailed Necklace, the Safflower, the Blackhead and the River Gull. The nest is located in a dimple of the earth formed with mussels, algae and grasses. It lays 2 to 4 eggs, one generation a year in the period May-June. Incubation lasts between 22 and 26 days. Little birds stay in the nest for just over three weeks.
Endangered species protected under the Biological Diversity Act. The main nesting sites are in protected areas.