Parasitic Jaeger

The Parasitic Jaeger, also known as the Arctic Skua in Europe, is a member of the skua family Stercorariidae. This seabird is recognized for its kleptoparasitic behavior, particularly during migration and winter, from which its name is derived. It exhibits three color morphs and is relatively small for a skua, with a length of 41–48 cm, a wingspan of 107–125 cm, and a weight ranging from 300 to 650 grams. The breeding adult's tail streamer contributes approximately 7 cm to its length.

Identification Tips

Adult light-morph Parasitic Jaegers have a brown back, predominantly white underparts, and dark primary wing feathers with a distinctive white "flash". Their head and neck are yellowish-white with a black cap, and they feature a pointed central tail projection. Dark-morph adults are uniformly dark brown, while intermediate-phase birds are dark with paler underparts, head, and neck. All morphs possess the white wing flash. Juveniles are more challenging to identify but are bulkier and less tern-like than long-tailed jaegers, with warmer, browner tones. Their flight is reminiscent of a falcon.

Habitat

The Parasitic Jaeger nests on dry tundra, higher fells, and islands, preferring open landscapes in the northern reaches of Eurasia and North America.

Distribution

This migratory species breeds in Northern Scandinavia, Scotland, Iceland, Greenland, Northern Canada, Alaska, and Siberia. It winters across the southern hemisphere, with a notable presence at sea in the tropics and southern oceans.

Behaviour

The Parasitic Jaeger is known for its aggressive defense of its nesting territory, often flying at the heads of intruders, including humans. It is a migratory bird, with overland migrations observed in various regions, such as the Canning River Valley in Alaska and from northern Russia to the Persian Gulf.

Song & Calls

The typical vocalization of the Parasitic Jaeger is a nasal mewing sound, often repeated during display. Its alarm call is a shorter, more abrupt sound.

Breeding

Breeding occurs in the northernmost parts of its range, with clutches of up to four olive-brown eggs. The species is usually silent, except for mewing and wailing notes on the breeding grounds.

Diet and Feeding

During the breeding season, the Parasitic Jaeger feeds on rodents, insects, eggs, chicks, and small birds. However, it primarily engages in kleptoparasitism, stealing food from other birds such as gulls and terns, especially in winter and on migration.

Conservation status

Regionally, the Parasitic Jaeger was uplisted to Endangered in Iceland in 2018 due to a significant decline in numbers. Globally, it is listed as Least Concern, indicating a stable population overall.