Pomarine Jaeger

The Pomarine Jaeger, known scientifically as Stercorarius pomarinus, is a robust seabird of the skua family Stercorariidae. It is a migrant, spending winters at sea in the tropical oceans. This large skua measures approximately 45cm in length, not including the elongated central tail feathers of the summer adult, which can add an extra 10cm. With a wingspan ranging from 110 to 138cm and a weight between 540–920g, it is larger than common gulls and presents a bulkier and broader-winged silhouette.

Identification Tips

Identifying the Pomarine Jaeger can be challenging due to its resemblance to the Parasitic Jaeger and the existence of three morphs. Light-morph adults exhibit a brown back, predominantly white underparts, and dark primary wing feathers with a distinctive white "flash". Their heads and necks are yellowish-white with a black cap. Dark morph adults are uniformly dark brown, while intermediate morphs are dark with slightly paler underparts, head, and neck. All morphs possess the white wing flash, which is particularly noticeable as a double flash on the underwing. In breeding adults, the two central tail feathers are conspicuously elongated, spoon-shaped, and twisted, setting them apart from other species. Juveniles pose an identification challenge and are best distinguished from Parasitic Jaegers by their plumage and structure at closer range.

Habitat

The Pomarine Jaeger breeds in the remote northern reaches of Eurasia and North America, favoring the Arctic tundra and islands.

Behaviour

This species is known for its aggressive defense of its nesting territory, often flying at the heads of intruders, which can be a rather alarming experience. It is also known for its piratical behavior, as it often robs other seabirds of their catches with remarkable agility.

Feeding

The diet of the Pomarine Jaeger is varied, including fish, carrion, scraps, smaller birds up to the size of common gulls, and rodents, with a particular preference for lemmings. It is an adept kleptoparasite, targeting gulls, terns, and even gannets for their food. The Great Black Backed Gull, White-Tailed Eagle, and Golden Eagle are among the few predators of healthy adult Pomarine Jaegers.

Conservation status

The Pomarine Jaeger is currently listed as Least Concern on the IUCN Red List of Threatened Species.