Stercorarius pomarinus
Pale and dark morphs. Often difficult to distinguish from Arctic Skua. Adults with broad, spoon-shaped streamers. These are moulted twice a year, so adults lacking these are not uncommon. The dark cap reaches around the bill base and down to the chin. Breast band in pale morph is generally broader and more pronounced than in Arctic Skua, but in some males it is lacking altogether. Leaves an overall more robust and powerful impression than Arctic. Wings are broader than the distance from trailing wing-edge to tip of tail (streamers excluded), while the hand seems shorter. The light patches at the base of the primaries are more obvious, and many young birds shows a characteristic double patch, formed by additional white base of greater primary coverts (like Lesser Spotted Eagle). Rump and vent of juveniles usually boldly barred, in contrast to unbarred back and belly (visible even in dark morph). Streamers never pointed (in any plumage). Flight pattern straighter, and more determined than in Arctic Skua.
Short "kea" or "ke", and various mewing calls, usually deeper pitched than Arctic Skua. Also a characteristic, laughing and vibrating "kayayayayaya", heard mostly on breeding ground.
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
CC-photo:loarie, Licence,Link.
CC-photo:jerryoldenettel, Licence,Link.
Sounds:CC. http://www.xeno-canto.org .Recorded by Andrew Spencer.
