Appearance:

A large shearwater with pale upperparts and heavy, yellowish bill. Large grey head. The grey neck forms a diagnostic, contrasting line from wing base to base of bill (most other shearwaters have white neck-sides). Armpits usually pure white. Underside of wings white, framed by black flight feathers. Flight action calm and distinct. Long glides alternates with 3-4 slow wingbeats. Wingtips always bent downwards, and wings slightly angled back. Often soars. Differs from Fulmar in dark tail, grey head, long, narrow wings and longer bill. The two subspecies C. diomedea and C. borealis, are somtimes treated as different species. Field identification of these usually impossible, and requires ideal conditions. Hand of borealis is darker due to no white fringes to primaries. In diomedea the white in the coverts extends in a white wedge into the hand, through the base of the primaries.

Sound:

Very vocal at breeding ground. Calls with a very nasal, comical, mewing "ke-kooeee", ending with falling pitch, like a releasing sigh or moan. Sometimes reltively pure, other times very hoarse and raucous.

At breeding ground (C. d. borealis):

Distribution:

Wikipedia: map (se also Xeno-canto below)

Ecology:

Birdlife ecology

Links:

Observation.org Latest observations

Video IBC

Image search Flickr NB! May give other species

Sound search at Xeno-canto

Featherbase

CC

CC-sound:James Bradley, Licence,Link.

CC-photo:Hans Verdaat, Licence,Link.

Appearance:

Unmistakable in breeding plumage, but otherwise easily confused with other marsh terns. Breeding plumage with black head and belly, but pale underwing and grey rump. When in immature and winter plumage it differs from Common and Arctic tern by smaller size and short, moderately forked tail, and from other marsh terns by slimmer body and wings (compared to White-winged tern), and relatively long, thin bill. Both immature and adult winter show dark front edge of wing, and characteristic dark shoulder patch at wing base. Back is dark in immature birds. Grey rump in all plumages. Flight usually different from Sterna-terns, with erratic dives for no apparent reason, and "aimless" change of direction. Note that when foraging over saltwater, flight becomes more Sterna-like.

Sound:

Moderately vocal. Flight call a more or less clear "kleck, or a disyllabic "klee-ake" with accented first syllable. Sometimes slightly rolling "klirr-eke", but never as much as in White-winged Tern. Also a slightly harsher "kreek", but not as raspy as in Whiskered Tern.

Flight call:

Distribution:

Wikipedia: map (se also Xeno-canto below)

Ecology:

Birdlife ecology

Links:

Observation.org Latest observations

Video IBC

Image search Flickr NB! May give other species

Sound search at Xeno-canto

Featherbase

CC

CC-sound:Ad Postma, Licence,Link.