Common Name
PARASITIC JAEGER

Scientific Name
STERCORARIUS PARASITICUS

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Photo by Bruce A. Sorrie
Photo Copyright Bruce A. Sorrie

The parasitic jaeger, Stercorarius parasiticus, breeds in the Canadian arctic, circumpolar regions, and along the coasts of Alaska, and it winters at sea. Parasitic jaegars normally migrate near (or along) the coasts, but they are occasionally seen inland in the Great Plains and the Great Basin. They are casual migrants to Utah, and are most frequently seen in marshes around the Great Salt Lake. The diet of the species consists of other birds, small mammals, fishes, insects, carrion, and sometimes seeds and berries. Although parasitic jaegers often prey on other birds, they will sometimes simply harass a bird until it drops its food; the food item is then stolen by the jaeger. Parasitic jaegers may also follow mammalian predators through nesting colonies and then take untended eggs before the mammal is able to do so. Parasitic jaegers may hunt alone, in pairs, or in small groups.

Parasitic jaegars are often colonial. The pair participates in a courtship feeding display, and a long-term pair bond is formed. The male selects a nesting location and the female constructs a nest by scraping a small area out of the earth on the tundra. Only occasionally will she line it with any material. Two eggs are incubated, and both parents sit on the nest for approximately one month. The young usually hatch at different times, and the younger chick generally disappears after the first few days. If the young are in danger, the parents will perform a distraction display.

Sources:

  • Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birderís handbook[:] a field guide to the natural history of North American birds. Simon & Schuster, New York. xxx + 785 pp.

  • National Geographic Society. 1996. Field guide to the birds of North America, 2nd edition. The National Geographic Society, Washington, D. C.

  • Behle, W. H., Sorensen, E. D. and C. M. White. 1985. Utah birds: a revised checklist. Utah Museum of Natural History, Occasional Publication No. 4. Salt Lake City, UT.

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