Montana Field Guide

Golden Eagle - Aquila chrysaetos

Adults are brown overall, gold on head and neck feathers, with light brown bands in the tail. Immature birds have white patches on the wings and white at the base of the tail feathers. Golden eagles often soar with their wings held nearly flat, but slightly upturned. The legs are heavily feathered down to the tops of the toes. Golden eagles range in length from 33-38 inches, and have a wingspan of 6-1/2 to 7-1/2 feet (FWP). A very large raptor with mostly brown plumage, a golden wash on the back of the head and neck, and a mostly horn-colored bill; tail is faintly banded; immatures have white at the base of the primaries and and white tail with a dark terminal band; total length 76-102 cm, wingspan 203-224 cm (NGS 1983).

Bald eagles have feathers only part way down the leg, and usually soar with wings held completely flat. immature bald eagles usually have a strip of white along the underside of the wing, rather than in a round patch on the flight feathers like the immature golden eagle. older immature bald eagles have irregular patches of white on their bodies, instead of the sharply defined patterns on golden eagles. turkey vultures soar with wings held in a more pronounced "v."

Montana Range

Migrants seen in Bridger Mountains in September-October. Many remain year-round, but vertical migration seen in spring and fall (Skaar 1969). In a 1991 study of fall migration along the Bridger Range, Omland and Hoffman (1996) concluded that immature Golden Eagles migrated earlier in the season than adults; immatures also spent more time each day migrating and/or were less selective about the time of day during which they migrated than adults. Further, the authors found no evidence of visual interaction among migrating Golden Eagles.

Golden eagles nest on cliffs and in large trees (occasionally on power poles), and hunt over prairie and open woodlands (FWP). Cliff nests selected for S or E aspect, < 200 snowfall, low elev., availability of sagebrush/grassland hunting areas (McGahan 1966). In Bozeman area, eagles move from mtns to val- leys in the winter (Skaar 1969).

In Montana, golden eagles eat primarily jackrabbits, ground squirrels, and carrion (dead animals). They occasionally prey on deer and antelope (mostly fawns), waterfowl, grouse, weasels, skunks, and other animals. Golden eagles rarely prey on livestock, but when they do, losses usually occur in areas where migrating eagles congregate. Golden eagles can carry no more than about seven pounds while flying (FWP).

Nesting density varies yr to yr from 55 to 105 sq.mi./pair. Eagles move to higher elevations after leaving nest (McGahan 1966, Baglien 1975).

Golden eagles first breed when four to five years old. The same pair often uses the same nest year after year; nests are sometimes over six feet in diameter. One to three eggs are laid in March or April, and incubated for about 45 days. The eaglets fly in June or July when about 10 weeks old (FWP). Eggs layed early Apr, hatch mid-May, fledge mid-Jul to early Aug. In S-central MT clutch ave. 2.1, w/ ca. 1.5 eaglets fledged per successful eyrie, and ca. 76% of nests success- ful (McGahan 1966, Reynolds 1969).