Swift (Apus apus)
Long-tailed Jaeger (Stercorarius longicaudus)
All black swift with small white throat patch. Very difficult to separate from Pallid swift and Plain Swift. Pallid Swift; brownish plumage tone (best seen against darker background), bigger throat-patch than swift, scale pattern on body more prominent, wing-tips slightly rounded, "saddle" darker than wings, and more contrast between darker outer primaries and inner. Plain Swift; throat patch smaller and more diffuse than swift, wings and body more slender, tail noticeably deeper forked.
Sound:A shrilling trill "zreeeee" of about 1 -2 seconds length, gradually rising in pitch with accentuated firs half, then falling from the middle of phrase. Often continued with a dry lower pitched "trrrrrr" before calling again. Very vocal at breeding area, and often a flock will call together. Despite being quite similar to Pallid Swift, the call is probably the best field character to separate the two. Pallid puts the stress on the ending of the call, followed by a quick fall in pitch (dynamics like moaning with a quick release). Plain Swift calls similar to Common Swift, but differs in slightly fluctuating pitch during the call, and a loss of resonance towards the ending (thinner sounding).
Song/contact 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
CCBreeding plumaged adults with streamers unmistakable (streamers comprising two thirds of total tail length). Adult plumage shows less variation than in other skuas. No hint of breast band, and transition between pale belly and darker vent very diffuse. No white patches at base of primaries of underwing in adults. Juveniles easily confused with juvenile Arctic Skua, but are more slender. Wings narrower and primaries and tail longer. Juvenile Arctic Skua shows white patches at base of primaries on both sides of wings, juvenile Long-tailed only on underwing, and on first few primaries of upper. Barred rump and tail coverts in juveniles. Flight elegant and buoyant.
Sound:Calls sharp and less full-bodied than Arctic Skua, and not so mewing. Short, double-accented "kew-wev" or short "kerk" in agitation. Also a long drawn-out "keeeeaah", resembling both Arctic Skua and Common Gull.
Alarm/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
CCSounds:Recorded by Andrew Spencer,http://www.xeno-canto.org ,CC license