Parasitic Jaeger

 The parasitic jaeger (Stercorarius parasiticus), also known as the Arctic skua, Arctic jaeger or parasitic skua, is a seabird in the skua family Stercorariidae. The word "jaeger" is derived from the German word Jäger, meaning "hunter". The English "skua" comes from the Faroese name skúgvur [ˈskɪkvʊər] for the great skua, with the island of Skúvoy known for its colony of that bird. The general Faroese term for skuas is kjógvi [ˈtʃɛkvə]. The genus name Stercorarius is Latin and means "of dung"; the food disgorged by other birds when pursued by skuas was once thought to be excrement. The specific parasiticus is from Latin and means "parasitic".

                                              

This is the most familiar of our jaegers since it comes more readily into bays and estuaries and often feeds closer to shore. Like the other jaegers, it usually obtains food by pursuing gulls and terns and forcing them to drop food.

DESCRIPTION

21" (53 cm). A fast-flying, gull-like seabird. Typical adults are brown above, white or light dusky below, with an incomplete gray-brown band across the breast; a dark, almost black, crown; and short (up to 3-4") pointed central tail feathers. Dark-phase birds are uniform dusky brown with a darker cap; intermediates between the two color phases occur. Often seen harrying gulls and terns.

Identification is complicated by similarities to long-tailed jaeger and pomarine jaeger, and the existence of three colour morphs. Small for a skua, the parasitic jaeger measures 41–48 cm (16–19 in) in length, 107–125 cm (42–49 in) in wingspan and weighs 300–650 g (11 oz – 1 lb 7 oz). The tail streamer of the breeding adult accounts for about 7 cm (3 in) of their length. Light-morph adults have a brown back, mainly white underparts and dark primary wing feathers with a white "flash". The head and neck are yellowish-white with a black cap and there is a pointed central tail projection. Dark-morph adults are dark brown, and intermediate-phase birds are dark with somewhat paler underparts, head and neck. All morphs have the white wing flash.

                                                

Identification of juveniles is even more problematic, and it is difficult to separate parasitic jaegers from long-tailed jaegers. Parasitic jaegers are bulkier, shorter-winged, and less tern-like than long-tailed jaegers. They are usually warmer toned, with browner shades, rather than grey. However, they show the same wide range of plumage variation. The flight is more falcon-like.

The typical call of these birds is a nasal mewing sound, repeated a few times in display. Their alarm call is a shorter sound.

VOICE

Usually silent; a variety of mewing and wailing notes on breeding grounds.

NESTING

2 olive-brown eggs, with darker brown spots, in a grass-lined depression on the ground or among rocks.

                                                 

HABITAT

Breeds on grassy tundra and stony ground near inland lakes; at other times on the ocean.

RANGE/MIGRATION

Breeds in Alaska and northern Canada. Winters in warm waters in Southern Hemisphere. Also in northern Eurasia.