Northern Prairie Wildlife Research Center
STATUS: Common in the far North, rare and local in the conterminous United States.
HABITAT: Found north of the tree line in arctic tundra, where it inhabits moss- and lichen-covered flatlands, lowlands, and valleys well dotted with frost-heave mounds, hillocks, or rocks. Avoids very marshy areas with no raised sites. During years of low lemming abundance, moves southward into the conterminous United States, onto open fields, sandy beaches, barrier islands, and marshes.
SPECIAL HABITAT REQUIREMENTS: Raised sites such as frost-heave mounds several yards in diameter and as much as 2 to 3 feet above the ground, large rocks, or other abrupt rises in the ground for roosting and nesting.
NEST: Generally nests at elevations less than 650 feet. Nests in a shallow depression on top of a frost-heave mound or other raised site, occasionally on a gravel bank, tidal flat, or on slopes above a marsh or lake. Rarely, nests in an abandoned eagle nest high in a tree.
FOOD: Kills a wide variety of mammals and birds, especially lemmings and mice. Throughout its summer and winter range, also preys on a variety of rodents, rabbits, waterfowl, shorebirds, songbirds, fish—almost any small animal that can be caught.
REFERENCES: Heintzelman 1979, Karalus and Eckert 1974, Udvardy 1977, Watson 1957.