The Common Tern (Sterna hirundo) is an elegant, sharply marked seabird often called the "sea swallow" for its long, deeply forked tail and buoyant flight. Adults show pale grey upperparts, white underparts, a black cap and nape, a red bill tipped with black, and short red legs. Measuring 31-35 cm with a wingspan of 77-98 cm, it hunts by plunge-diving for small fish from heights of 3-10 metres, a spectacular and highly visible feeding technique along Swedish coasts and lakes.
At the breeding colony the Common Tern is anything but quiet, giving a sharp "krriä-krri-krri" and a harder "kik-kik-kik", and pairs defend their nests fiercely, dive-bombing anything large that approaches, humans included. The species breeds in colonies on coastal skerries, islets and sandy shores, as well as on sandy islands in larger inland lakes, laying 2-3 eggs incubated for 21-22 days. Sweden holds a population of roughly 25,000-35,000 pairs. Common Terns are long-distance migrants, arriving in April-May and departing again by August-September for wintering grounds in West Africa. They are best looked for from May to August around skerries, sandy islets and larger lakes, where their harsh calls and plunge-diving give them away long before they are seen up close. Every part of the colony's defence, from the shrieking alarm calls to the sudden dives, is aimed at keeping predators and intruders well away from the exposed nests.
Read about this species in Swedish →