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Long-tailed jaeger | Stercorarius longicaudus
Kleinste jager | Págalo rabero
The long-tailed jaeger is the lightest and slimmest of the four, with a buoyant, tern-like flight and, in adults, two tail streamers trailing half a body length behind. Along the Dutch coast it is a scarce bird, seen mostly in the last days of May or during an autumn blow.
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Voice
Away from the breeding grounds it is virtually silent: a bird passing the Dutch coast will make no sound at all. On the tundra it is noisy enough, with a sharp, nasal kreh-kreh-kreh in display flight and a hard kip-kip when attacking intruders at the nest. The voice belongs to the breeding ground rather than to the seawatch point — a recording of a passing migrant effectively does not exist.
Recording: Teet Sirotkin — CC BY-SA 4.0 · xeno-canto
Identification
Small and narrow-bodied, with a short thick bill, a long pointed hand and a pale grey mantle contrasting clearly with the black trailing edge of the wing and the black tail. Adults have a neat black cap, a yellowish-white neck and a white breast that shades without any sharp breast band into a grey belly and black undertail coverts; the two central tail feathers are thin, flexible and pointed and project up to about twenty centimetres. The clincher is the primary pattern: only two — sometimes three — white shafts, so that from above there is barely a pale wing flash, where the other jaegers show an obvious white patch. Juveniles are difficult: cold greyish brown, with crisply barred black-and-white upper- and undertail coverts, often a strikingly pale head, and a short blunt tail projection; the most useful feature is the bicoloured bill, whose dark tip is sharply defined and covers less than half its length.
Confusion species
Parasitic jaeger is larger and heavier, with a longer hand, far more white in the primaries, usually a dark breast band in pale adults, and straight, stiff, pointed streamers five to eight centimetres long. Pomarine jaeger is markedly bulkier with a barrel-chested body, a heavy bicoloured bill and, in adults, twisted spoon-shaped streamers. Great skua is huge, uniformly brown and shows broad white wing flashes. In juveniles the four can be separated only on structure, bill pattern and the crispness of the barring; if you are still unsure after a few seconds of seawatching, the honest record is jaeger sp.
Habitat
It breeds on dry open tundra and stony mountain heath above the tree line in Fennoscandia and Russia, living almost entirely on lemmings; in poor lemming years a whole region may fail to breed at all. Outside the breeding season it is wholly pelagic, wintering over open water in the southern Atlantic far out of sight of land. On migration it robs other birds less than its relatives do and picks much of its food from the surface itself, so it rarely trails ships or tern colonies.
Where the bird is most at home, classified with EUNIS — the European standard for habitats.
Range and movements
It breeds right around the Arctic; in Europe in the Norwegian and Swedish fells, Finnish Lapland and northern Russia, in strongly fluctuating numbers. The migration route runs largely far out to sea, so the North Sea coast catches only the edge of it: a few tens of birds a year, with a small spring peak in late May and the main passage in August and September. Along the Atlantic coast of Iberia it is seen mainly off Galicia and the Basque Country, on autumn seawatches and on pelagic trips over the shelf edge, and the passage reaches down to Mauritania.
- Breeding (summer)
- Passage
- dark = core range, pale = thinly spread
How and when to look
Seawatching is the only realistic chance: take a pier head or an established watchpoint in the second half of August or early September with a persistent north-westerly of force 5 to 7. Most Long-tailed jaegers pass in the first hours after sunrise, high and fast and usually away from the stream of gulls. In late May a north-easterly can bring an adult in full plumage past the coast; that is the one moment when identification is genuinely easy.
Conservation status
Least Concern globally, with a large world population, but Fennoscandian numbers swing violently with the lemming cycle. The weakening of that cycle in warmer, wetter winters is the main concern: without lemming peaks, entire regions may go years with almost no breeding. At sea it is little exposed to fisheries, since unlike the larger jaegers it seldom follows ships.
Scientific name
Stercorarius longicaudus | Vieillot, 1819
Vieillot described the species in 1819 and placed it straight away in the genus where it still stands. 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. longicaudus is Latin, from longus 'long' and cauda 'tail', after the long central tail feathers of the adult. The specimen the first description was based on came from northern Europe.