Parasitic Jaeger
Parasitic Jaeger
Stercorarius parasiticus
At a Glance
This is the mid-sized member of the jaeger trio, and the most familiar, as it is the one most likely to be seen from shore. Variable in plumage, it occurs in dark, light, and intermediate morphs.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Gull-like Birds, Gulls and Terns
IUCN Status
Least Concern
Habitat
Coasts and Shorelines, Lakes, Ponds, and Rivers, Open Ocean, Tundra and Boreal Habitats
Region
Alaska and The North, California, Eastern Canada, Florida, Great Lakes, Mid Atlantic, New England, Northwest, Plains, Rocky Mountains, Southeast, Southwest, Texas, Western Canada
Behavior
Direct Flight, Swimming
Population
3.500.000
Range & Identification
Migration & Range Maps
Often seems to follow general trend of coastline, a few miles offshore; some may regularly migrate over land. A few remain in winter as far north as North American waters but most go farther south, some reaching southern Australia, Africa, South America.
Description
21" (53 cm). Adult has fairly short, pointed central tail feathers. Varies from dark gray to whitish below, usually with dark chest band; often less barred, grayer-headed than Pomarine Jaeger. Juvenile in first fall dark brown with buff bars. Later immature stages variable.
Size
About the size of a Crow, About the size of a Mallard or Herring Gull
Color
Black, Brown, Tan, White
Wing Shape
Broad, Pointed, Tapered
Tail Shape
Long, Pointed, Square-tipped, Wedge-shaped
Songs and Calls
Usually silent; a variety of mewing and wailing notes on breeding grounds.
Call Pattern
Falling, Flat, Rising
Call Type
Scream
Habitat
Ocean, coastal bays, lakes (rarely); tundra (summer). Spends most of year at sea, concentrating over continental shelf within a few miles of land, rarely far out in mid-ocean. Breeds in open country of far north, mostly tundra, also rocky barrens and coastal marshes. Immatures and non-breeders may remain at sea all year.
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Behavior
Eggs
2, sometimes 1-3. Olive to brown, rarely blue, spotted with brown. Incubation is by both sexes, 25-28 days.
Young
Downy young may leave nest a few days after hatching, but remain in vicinity. Both parents feed young, by regurgitation. Young can fly at 25-30 days, but remain with parents for a few more weeks.
Feeding Behavior
At sea, does much of foraging by chasing other birds and forcing them to drop their catch; also dips down in flight to catch fish at surface. On breeding grounds, also hovers and swoops down to catch prey, and feeds while walking.
Diet
Includes fish, birds, rodents. Diet at sea and at coastal nesting areas is mostly fish stolen from other birds. On land, also eats many birds and their eggs, rodents, insects, berries. Less dependent on lemmings and other rodents than the other jaegers.
Nesting
Usually first breeds at age of 4-5 years; in one study in Europe, birds of pale morph tended to start nesting younger than dark birds. May nest in colonies or in isolated pairs. Early in breeding season, pairs or groups perform acrobatic display flights. Courtship involves upright posturing, calling; male feeds female. Nest site (selected by male) is on the ground in the open, sometimes on a slight rise. Nest (built mostly by female) is a shallow depression, usually with a sparse lining of plant material.
Conservation
Conservation Status
Most of breeding range is remote from human impacts. No evidence of major changes in population.
Climate Threats Facing the Parasitic Jaeger
Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.