Wiley, R. H., and D. S. Lee. 1998. Long-tailed Jaeger (Stercorarius
longicaudus). In The Birds of North America, No. 365 (A.
Poole and F. Gill, eds.). The Birds of North America, Philadelphia, PA.
f the three species of Stercorarius, the Long-tailed Jaeger
is the smallest and most graceful in flight. Transequatorial migration
allows this species to forage in regions with high productivity and
extended day lengths throughout the year. During the breeding season, it
feeds over arctic tundra; as a migrant and through- out the northern
it is highly pelagic, spending its time over open seas.
Even though this jaeger spends more than three-fourths of its life at
sea, nearly all information about its biology comes from its arctic
breeding grounds. The species is seldom seen in North America south of
Canada and Alaska, and much of the published information not directly
related to its breeding biology focuses on vagrancy or identification.
In the Arctic this species is the most widely distributed and abundant
jaeger. Breeding the farthest north of any jaeger, probably as far north
as any bird, during the summer it frequents dry tundra, sometimes even
barrens, on low slopes and ridges. Its diet in this habitat consists
lemmings and voles, so this bird is vulnerable to cycles in the densities
The Long-tailed Jaeger is supremely adapted for predation on these
cyclic rodents. Because it depends on rodents only for breeding, it can
survive crashes in rodent numbers without the irruptions and high
mortality experienced by other arctic predators. In years with low
densities of lemmings, the Long-tailed Jaeger simply does not breed and
returns to sea. In effect it "skims the cream" from the population cycles
Migrant Long-tailed Jaegers are usually encountered singly. Most
individuals migrate over the open ocean. Jaegers in general, and the two
smaller species in particular, are difficult to separate. The challenges
of identification result from the conservation plumages of the genus and
from individual, age-related, and polymorphic variation. Many birds seen
away from nesting areas are not in the distinctive adult breeding plumage
and thus lack the characteristic central tail-feathers and other features
of this plumage.