Appearance:

Olive green upperparts, yellowish chest with gradual transition to off-white belly. Very similar to Willow Warbler, and most field characters are subtle and often hard to see. Distinguished by (usually) black, or dark-brown legs, only faint dark framing to ear-coverts, less marked supercilium. Shorter primary projection (1/2 to 2/3'rds the lenght of tertials), with regularly spaced tips (visible when wing folded). Wings more fan-shaped and less pointed than in Willow Warbler. Juveniles much less yellow below than in W.Warbler. Generally leaves a duller and greyer impression than W. Warbler, but plumage very variable. Frequently flicks tail, even sideways. Generally also more active when moving among the foliage.

Sound:

Contact/alarm call a soft, plaintive ascending "hooeet". Similar to W.Warbler, but shorter with a monosyllabic feel. Song a very distinct: "chiff-chaff-chiff-chiff-chaff-chiff", in a regular clock-like rhythm. Each syllable at seemingly random pitch, but no large intervals tonally. Sometimes "get stuck" at one note.

Contact call, song:

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

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.