Long-tailed jaeger (Stercorarius longicaudus)

Also known as: long-tailed skua
  
French: Labbe à longue queue
KingdomAnimalia
PhylumChordata
ClassAves
OrderCharadriiformes
FamilyStercorariidae
GenusStercorarius (1)
SizeLength including tail streamers: 48 - 53 cm (2)
Wingspan: 105 - 117 cm (2)
Weight230 - 444 g (2) (3)

The long-tailed jaeger is classified as Least Concern (LC) on the IUCN Red List (1).

The smallest and most graceful of the Stercorarius species, the long-tailed jaeger (Stercorarius longicaudus) is named for its greatly elongated central tail feathers (2) (3) (4). These long, pointed, flexible feathers are only present in breeding adults (3), and can measure up to 22 centimetres in length (2).

Also known as the long-tailed skua, the long-tailed jaeger has a slim body, narrow wings and a relatively small head (2) (4). During the breeding season, the adult is largely grey above, with a whitish head, blackish-brown cap, and a whitish neck with yellowish sides (3) (4). The underparts are white, shading to grey (4), and the flight feathers are blackish, with contrasting pale shafts on the two outermost primary feathers (3). The bill is black and the legs are grey-blue, with black feet (3). Female long-tailed jaegers average slightly larger than males, but are otherwise similar in appearance, although the male may be slightly whiter below (3).

Outside the breeding season, the adult long-tailed jaeger loses its long central tail feathers and becomes browner and more barred (3). The juvenile is variable in appearance, but is usually barred brown and whitish, with shorter central tail feathers which have rounded rather than pointed tips (3). It also shows patches of white on the wing, which the adults lack (4). The juvenile long-tailed jaeger can occur in two colour morphs: a light morph, which has a brown, white or greyish head, neck and breast, and a pale abdomen, usually barred with brown; and a rarer dark morph, which is similar but with dark underparts and a darker brown head (3). A dark morph has also been reported in adults, but is probably extremely rare (2) (3) (4).

Two subspecies of the long-tailed jaeger have been described, with Stercorarius longicaudus pallescens having whiter underparts than Stercorarius longicaudus longicaudas (2). The long-tailed jaeger produces three main calls: ‘kreck’, ‘kliu’ and ‘kuep’. The ‘kreck’ call is given specifically when swooping to attack mammals intruding on the jaeger’s territory, while ‘kliu’ is given specifically for intruding birds. These two calls are also combined into a longer call, used in territorial displays (3) (5).

The long-tailed jaeger breeds in the high Arctic of Eurasia and North America (2) (3) (6), where it is the most widely distributed and most northerly breeding jaeger species (3). S. l. longicaudus breeds from Scandinavia to Russia, east as far as the River Lena, while S. l. pallescens breeds in Greenland, North America, and in Siberia east of the River Lena (2).

A migratory species, the long-tailed jaeger spends the non-breeding season around the southern oceans, including off the coasts of southern South America and southern Africa. However, its exact winter distribution is not completely understood (2) (3) (6).

Outside of the breeding season, the long-tailed jaeger spends most of its time at sea, rarely within sight of land (2) (3) (6). However, it returns to land to breed, nesting on Arctic and sub-Arctic tundra (2) (3) (4) (6), at elevations of up to 1,300 metres (2). It prefers to nest on dry ground, often quite far inland (2) (3).

On its breeding grounds, the long-tailed jaeger specialises in feeding on rodents, particularly lemmings and voles (2) (3) (5) (7) (8). The populations of its rodent prey often vary widely from year to year, peaking around every four to five years. In years of low rodent abundance, the long-tailed jaeger relies more on young birds, shrews, insects and berries (2) (3) (5) (7) (8) (9). It will also scavenge, and sometimes steals food from other birds (2) (3). The winter diet of this species is not well known, but may include fish, marine invertebrates, crustaceans and carrion (2) (3).

The long-tailed jaeger hunts rodents by hovering some distance above the ground, before pouncing on or pursuing the prey on the ground and pecking it to death (2) (3) (5). It cannot use its feet to grasp prey, instead usually shaking the rodent in the beak to break it apart (3) (5). Adult lemmings may be too large to be eaten whole, but a breeding pair will often cooperate to tear apart prey (2) (3) (5).

A highly territorial species, the long-tailed jaeger defends a large area around the nest, chasing away intruders and attacking any predators that come near (2) (3) (5) (8). The nest consists of an unlined scrape, usually on a gentle slope or low mound with a good view of the surrounding area (2) (3) (5). Nesting begins in June, after the snow has melted (2) (3) (5) (7) (8) (10). The maximum clutch size of the long-tailed jaeger is two, but its breeding behaviour is closely linked to rodent availability, and in years of lower abundance many pairs lay only one egg. In the lowest rodent years, many or even most pairs will not nest at all (2) (3) (5) (8) (10) (11).

The eggs of the long-tailed jaeger are incubated for around 23 to 25 days (2) (3) (7) (8). The chicks leave the nest one to two days after hatching, and hide some distance apart in low vegetation to avoid predators such as the Arctic fox (Vulpes lagopus) (2) (3) (5) (8). The female long-tailed jaeger undertakes most of the care of the young, while the male does most of the hunting and territory defence (3) (5). Young chicks are fed mostly on insects and berries (9) and must have rodents torn apart for them (3). However, after about a week the young can cooperate with the female to tear apart prey (5). The young long-tailed jaegers fledge after around 22 to 27 days (2) (3) (7) (8), but may not breed for the first time until they reach 3 or 4 years old (2) (3). This species is thought to live to at least eight or nine years old (3).

After breeding, the long-tailed jaeger migrates south from August to October (2) (3), although adults that have not successfully bred usually leave earlier (7). Juveniles may spend the whole of the first few years of life at sea (9). Non-breeding long-tailed jaegers may gather in small flocks to forage or roost (3).

With its large population and extensive range, the long-tailed jaeger is not currently considered at risk of extinction (6). However, a potential threat to this species is likely to come from the disruption of lemming population cycles due to climate change (12). It is also sometimes shot for dog food in Greenland and may be affected by marine pollution (3).

The long-tailed jaeger is listed on Appendix II of the African-Eurasian Waterbird Agreement (AEWA), which calls on parties to undertake conservation action for birds which rely on wetlands for at least part of their annual cycle (13).

There are no known specific conservation measures in place for the long-tailed jaeger, but it may benefit from further study into its migration routes, wintering areas, and possible contamination by marine pollution (3). This species’ conspicuousness and its reliance on rodent populations would also make it a useful subject for monitoring the overall ‘health’ of Arctic ecosystems (3).

Find out more about the long-tailed jaeger and its conservation:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (February, 2011)
    http://www.iucnredlist.org/
  2. del Hoyo, J., Elliott, A. and Sargatal, J. (1996) Handbook of the Birds of the World. Volume 3: Hoatzin to Auks. Lynx Edicions, Barcelona.
  3. Wiley, R.H. and Lee, D.S. (1998) Long-tailed jaeger (Stercorarius longicaudus). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
    http://bna.birds.cornell.edu/bna/species/365/articles/introduction
  4. Peterson, R.T., Mountfort, G. and Hollom, P.A.D. (1993) Collins Field Guide: Birds of Britain and Europe. HarperCollins Publishers, London.
  5. Andersson, M. (1971) Breeding behaviour of the long-tailed skua Stercorarius longicaudus (Vieillot). Ornis Scandinavica, 2(1): 35-54.
  6. BirdLife International (February, 2011)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=3202
  7. Maher, W.J. (1970) Ecology of the long-tailed jaeger at Lake Hazen, Ellesmere Island. Arctic, 23(2): 112-129.
  8. Andersson, M. (1976) Population ecology of the long-tailed skua (Stercorarius longicaudus Vieill.). Journal of Animal Ecology, 45(2): 537-559.
  9. de Korte, J. and Wattel, J. (1988) Food and breeding success of the long-tailed skua at Scoresby Sund, Northeast Greenland. Ardea, 76: 27-41.
  10. Andersson, M. (1981) Reproductive tactics of the long-tailed skua Stercorarius longicaudus. Oikos, 37: 287-294.
  11. Meltofte, H. and Høye, T.T. (2007) Reproductive response to fluctuating lemming density and climate of the long-tailed skua Stercorarius longicaudus at Zackenberg, Northeast Greenland, 1996-2006. Dansk Ornitologisk Forenings Tidsskrift, 101: 109-119.
  12. Gilg, O., Sittler, B. and Hanski, I. (2009) Climate change and cyclic predator-prey population dynamics in the high Arctic. Global Change Biology, 15: 2634-2652.
  13. Agreement on the Conservation of African-Eurasian Migratory Waterbirds (February, 2011)
    http://www.unep-aewa.org/