All species › Waders, gulls and terns › Skuas › Parasitic jaeger

Parasitic jaeger | Stercorarius parasiticus

Kleine jager | Págalo parásito

The parasitic jaeger is by far the commonest jaeger along the Dutch coast and the only one you will regularly see chasing a tern. It flies like a falcon, agile and quick, with a narrow hand and, in adults, two pointed, dead-straight tail streamers.

Parasitic jaeger (Stercorarius parasiticus) — **Main photo** · Photo: Charles J. Sharp — CC BY-SA 4.0 · Wikimedia Commons

Click a thumbnail to switch the photo above.

Colour forms

Parasitic jaeger, pale morph, with a black cap and white underparts — **Pale morph, with a black cap and white underparts** · Photo: AWeith — CC BY-SA 4.0 · Wikimedia Commons

Parasitic jaeger, dark morph, uniformly sooty brown — **Dark morph, uniformly sooty brown** · Photo: Alaska Region U.S. Fish & Wildlife Service — Public domain · Wikimedia Commons

Voice

Silent at sea; noisy only in the colony. There it gives a mewing, almost cat-like kee-aaw in display flight and a hard, nasal tuk-tuk as it dives at a walker or a fox. The recording offered here comes from a breeding site accordingly: a bird passing the Dutch coast will in practice make no sound at all.

Listen: Alarm calls at the nestXC609518

Recording: Doug Hynes — CC BY-SA 4.0 · Wikimedia Commons

Identification

Medium-sized and slim, with a fairly small head, a fine dark bill and a light, extremely agile flight. Adults occur in a pale and a dark morph with every intermediate: pale birds have a black cap, yellowish neck sides, white underparts and usually a faint greyish-brown breast band, while dark birds are uniformly sooty brown with a slightly paler head. The elongated central tail feathers of adults are straight, stiff and sharply pointed and project five to eight centimetres; by autumn they are often broken off. In every plumage there is a clear white primary flash above and below the wing, formed by four to six white shafts. Juveniles are warm brown to rufous, closely and finely barred, with a streaked head and a short but pointed tail projection.

Confusion species

Pomarine jaeger is larger and heavier, with a barrel chest, slower and stiffer wingbeats, a heavier bicoloured bill and, in adults, twisted spoon-shaped streamers; its juveniles look colder greyish brown, have a plainer head and show a double white flash on the underwing instead of a single one. Long-tailed jaeger is smaller and finer, with a short bill, grey rather than brown upperparts and almost no white in the hand. Great skua is huge, uniformly brown, broad-winged and short-tailed. A jaeger chasing a Common or sandwich tern in over the dunes is, in the Netherlands, almost always this species.

Habitat

It breeds in loose colonies on coastal heath, tundra, islets and saltmarsh in northern Europe, usually within reach of tern and auk colonies whose catch it robs. Outside the breeding season it lives at sea, taking herring-family fish by chasing gulls and terns until they drop what they are carrying. On migration it follows the coastline and the movement of terns, and so comes closer inshore than the other jaegers.

Where the bird is most at home, classified with EUNIS — the European standard for habitats.

Range and movements

It breeds from Iceland and Scotland through Norway and Sweden to northern Russia; the Orkney and Shetland colonies have more than halved within a few decades. Further south only a migrant: along the North Sea coast several thousand pass each year from late July to mid-October, by far the most of them on strong westerlies. Off the Cantabrian and Galician coasts and through the Strait of Gibraltar a regular migrant, on down the Moroccan coast, and in smaller numbers along the Mediterranean too.

Resident
Breeding (summer)
Winter
Passage
dark = core range, pale = thinly spread

Density map from the occurrence records of GBIF (2006-09-01 – 2026-08-31), counted per 0.7° grid cell and per month and divided by all bird records in that same cell — so the number of birdwatchers does not shape the picture. Colour depth follows that share and fades out gradually, so the map does not follow national borders. Country outlines: Natural Earth (public domain).

How and when to look

Pick a seawatching point — the head of a pier or dam on the North Sea, a Galician headland or the Strait of Gibraltar — on a north-westerly of force 5 to 7 in August or September, and watch the first three hours after sunrise. Above all, watch the terns: where a party of Common or Sandwich terns suddenly turns edgy, there is nearly always a Parasitic jaeger in it. With offshore wind and a flat sea the odds are poor; here the weather matters more than the date.

Conservation status

Least Concern globally, but the European breeding population is falling fast: down by well over half on the Scottish isles since the 1990s. Food shortage following the collapse of the sandeel stock, and predation by the much larger great skua, are the main causes. Norway and Iceland look somewhat better, but declines are reported there too, and passage along our coast follows that trend with a lag.

Scientific name

Stercorarius parasiticus | (Linnaeus, 1758)

Linnaeus described the species in 1758 as Larus parasiticus; because it was later moved to another genus, the author and year stand in brackets. The genus Stercorarius was introduced in 1760 by Brisson. Stercorarius is Latin for 'of dung', from stercus 'dung': the food disgorged by seabirds when pursued by skuas was once taken for excrement. parasiticus is Latin for 'parasitic', after the habit of robbing other seabirds of their catch. The specimen the first description was based on came from the coast of Sweden.