Arctic Tern/Sterna paradisaea - Adult

Arctic Tern/Sterna paradisaea - Photographer: Борис Белчев
Arctic Tern/Sterna paradisaea - Photographer: Борис Белчев
Arctic Tern/Sterna paradisaea - Photographer: Симеон Гигов
Arctic Tern/Sterna paradisaea - Photographer: Димитър Георгиев

L 33-39 cm (incl. tail-streamers 7-11½ on ad.), WS 66-77cm. Breeds in colonies (in N often very large and dense) or singly along coasts, on islands in sea-bays, locally at ponds in taiga or barren mountains, and on tundra near water. Summer visitor (end Apr-Oct), winters off S Africa and Antarctica. Probably has the longest migration of all birds.
IDENTIFICATION: Very similar to Common Tern (see above); Arctic told by: slightly smaller size; shorter bill, head and neck and longer tail, making wings look ahead of centre of body; very short legs; slightly narrower wings. Flight often more elastic and gracefully bouncing than Common Tern’s, but display-flight of latter is just as elegant. Often dives with ‘stepped hover’, dropping short distance and hovering again before final plunge; at times snatches prey from surface in Black Tern fashion. - Adult summer: Bill dark red (blood-red) without black tip; lower throat, breast and belly washed grey, creating subtle contrast with white upper throat and cheeks, stronger than on most Common Terns; long tail-streamers extending beyond wing-tip when perched. Upperwing uniformly pale grey (lacking dark wedge or ‘notch’ of Common), and all flight-feathers near-white and translucent from below, outer primaries with neat black trailing edge (narrower than on Common). - Juvenile: Carpal bar often fainter than on normal Common Tern, and secondaries are whitish, not shaded grey as on Common Tern; often a white triangular area on hindwing. Dark bill first red-based, from Aug/Sep all black. Forehead white (more clearly demarcated than on Common). - 1stsummer (scarce in Europe): White forehead, dark bill, a faint dark carpal bar (thus resembles adult winter).
VOICE: Recalls Common Tern; includes piping, clear ‘pi-pi-pi-pi-…’, pyu pyu pyu’, and ringing ‘prree-eh’, and quarrelling, hard rattling ‘kt-kt-kt-krrr-kt-…’; alarm disyllabic ‘krri-errrrr’ (variable, like Common’s or harder, drier).

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