Feeding Behavior

Searches for prey by soaring high or by flying low over slopes; also watches for prey from high perches. When prey is spotted, eagle plunges to capture it in talons. Members of a pair sometime hunt together, with the second bird capturing prey that evades the first.

Eggs

2, sometimes 1-3, rarely 4. Whitish to buff, marked with brown. Sometimes one egg in the clutch is unmarked. Incubation is by both parents (female does more), 41-45 days. Young: Female remains with young most of the time at first, while male does most hunting, bringing prey to nest. After young are half-grown, female also does much hunting. Age of young at first flight roughly 60-70 days.

Young

Female remains with young most of the time at first, while male does most hunting, bringing prey to nest. After young are half-grown, female also does much hunting. Age of young at first flight roughly 60-70 days.

Diet

Mostly small mammals. Typically preys on mammals ranging in size from ground squirrels up to prairie-dogs, marmots, and jackrabbits. May take smaller rodents (voles and mice) or larger animals such as foxes, young pronghorns, or young deer on occasion. Also eats birds, mostly gamebirds such as grouse but rarely birds as large as cranes or as small as sparrows. Also some snakes, lizards, large insects. Will feed on carrion, including dead fish.

Nesting

May mate for life. In courtship, 2 birds circle high in air, making shallow dives at each other. Display to defend territory includes repeated high flight followed by steep dives, loops, rolls, and other acrobatics. Nest site is most often on cliff ledge, also frequently in large tree, rarely on ground. Sites may be used for many years. A pair may have 2 or more alternate nest sites, using them in different years. Nest (built by both sexes) a bulky platform of sticks, lined with weeds, grass, leaves, moss. New material added each year, and nest may become huge.