Black Tern (Chlidonias niger)
River Warbler (Locustella fluviatilis)
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
Image search Flickr NB! May give other species
CCA long-tailed and relatively long-winged Locustella, with olive-brown plumage and pale belly. Conspicuously broad, rounded tail, and substantial vent. Under tail coverts brown with with prominent pale fringes, and almost reaches tail tip. Faintly streaked throat and breast. Rump and tail warmer brown than back. Faint and short supercilium and pale eye-ring. First long primary with pale outer web, and a slight curve. Song-posts often more exposed than Grasshopper Warbler.
Sound:Song an insectlike, buzzing like Grasshopper and Savi's Warbler, but easily distinguished from those by it's distinct steam locomotive-like rhythm. About 8 accents per second. Perhaps easier to confuse with certain species of ground crickets or cicadas than it's congeners. Contact call a sharp "tsikk-tsikk", similar to Savi's Warbler.
Song:
Distribution:
Xeno-canto: map
Ecology:Birdlife ecology
Links:
Observation.org Latest observations
Image search Flickr NB! May give other species
CC