Pomarine Jaeger

Stercorarius pomarinus

Photo by tcollins
Photographed at darwin NT Aust

Photo by IanF
Dark phased - Photographed at North Gare, Seaton Carew, Cleveland,UK.

Identification

Also known as Pomarine Skua.

45cm length, excluding the central tail feathers of the summer adult, which can add another 10cm or so. It is similar to the Arctic Skua. It has a brown back, white underparts, dark primary wing feathers which have a white flash. Its head and neck are yellow-white. It has a black cap. Juveniles have paler underparts, head and neck.

Distribution

Far north of Eurasia and North America. It is a migrant, wintering at sea in the tropical oceans.

Taxonomy

The Pomarine Skua, known as Pomarine Jaeger in North America, is a seabird in the skua family Stercorariidae. Its relationships are not fully resolved; its mitochondrial DNA is most similar to the Great Skua [Blechschmidt et al., 1993], but from morphology and behavior, it is closer to the lesser skuas (such as the Arctic Skua). The most likely explanation is extensive hybridization between the Great and one species of lesser Skuas, which resulted in a hybrid population that eventually evolved into a distinct species, the Pomarine Skua; or alternatively between the Pomarine and a species of Southern Hemisphere skua, with the Great Skua being the hybrid offspring, perhaps appearing as recently as the 15th century [Blechschmidt et al., 1993; Furness and Hamer, 2003]. Judging from characteristics of the skeleton and behavior, the former seems more likely, as the Pomarine Skua shares several similarities with the "Catharacta" Skuas, while the Great Skua does not seem much different from its Southern Hemisphere relatives.

The mtDNA difference between the Pomarine and the Great Skua is one of the smallest between any two vertebrate species yet analyzed, being less than the variation found between different individuals of wide-spread species. The apparent capability for hybridization has led to the abolition of the separate genus Catharacta for the Southern Hemisphere and Great Skuas.

Habitat

It nests on arctic tundra and islands

Behaviour

It lays 2-3 olive-brown eggs in grass lined depressions.

Its diet includes lemmings and other rodents on the breeding grounds.

It will also kill birds up to the size of Common Gull.

Bird Song

<flashmp3>Stercorarius pomarinus (song).mp3</flashmp3>
Listen in an external program

External Links

Search for photos of Pomarine Jaeger in the gallery

• View more images of this species on the ABID
• View more images of this species on Orientalbirdimages