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APRIL 2006 BIRD OF THE MONTH |
BALD EAGLE OR
GOLDEN EAGLE?
By
Ben Long, FAS Member
CLICK HERE FOR .PDF VERSION
Flathead County is fortunate to host
both of North America’s eagles. Both are majestic,
but they are unique and not even closely
related species: the bald eagle and the golden
eagle.
Both birds are roughly the same size—
about three feet long, a wing-span of about six
feet and weighing roughly 10-12 pounds. They
both have sharp eyes, strong talons and sharp
beaks and cover vast distances by soaring. Individuals of both species have
lived upwards of 50 years in captivity.
The bald eagle is one of the most widely recognized wild birds in America and is the symbol of the
United States. It’s remarkable that the bald eagle was at risk of extinction only 30 years ago because of
habitat loss, pesticide poisoning and illegal killing. The bald eagle’s ongoing recovery is a success story of
the Endangered Species Act.
The two eagles prefer different habitats and have different habits. Both species will scavenge carrion,
and thus they can both be seen feeding on carcasses of road-killed deer, particularly in the winter. Of
the two, bald eagles seem somewhat more inclined toward scavenging.
Bald eagles are closely associated with water, be it inland lakes and rivers or the ocean coast.
Wherever it lives, waterfowl and fish are among its favorite prey. Bald eagles frequent the shore of Flathead
Lake, keeping careful watch on the rafting flocks of coots resting on the open water. Glacier National
Park’s lower McDonald Creek was once famous for its eagle congregations during the spawning runs of
kokanee salmon. Those congregations disappeared when the kokanee crashed in the late 1980s. Resident
bald eagle numbers have remained strong in the Flathead Basin and their massive nests of sticks are distributed
along our waterways.
Golden eagles are the creature of prairies and alpine. They are more strictly hunters of small mammals.
Favorite prey includes marmots in the alpine and jackrabbits and ground squirrels in the prairies and
steppes, although they have been seen taking animals as large as small deer and mountain goats. Golden
eagles stage dramatic annual migrations, between the tundra of the far north and warmer climates of the
desert southwest and Mexico. They follow the Continental Divide and Rocky Mountain Trench from north to
south in the autumn. This route funnels thousands of golden eagles over the Flathead, soaring south along
the Whitefish Divide, the Continental Divide and the Swan Crest in the autumn.
Where the bald eagle is almost entirely a creature of North America, golden eagles soar over much
of the northern hemisphere, nesting in North America, Europe, Asia and even portions of northern Africa.
When viewing mature birds, it’s a relatively simple matter to distinguish between golden and bald
eagles. Mature bald eagles have bold white heads and tails, contrasting with nearly black plumage of the
body and wings, a pattern that stands out at great distance. Golden eagles are duller overall, but distinguished
by a bronze-to-gold colored wash, particularly over the head and nape.
Identification becomes more challenging when examining immature birds. Bald eagles do not obtain
their distinctive white heads and tails until they are four or five years old. However, immature golden
eagles have white bands in the arc of the tail and a white spot in their “armpit” or underwing. Immature bald
eagles tend to show an overall white mottling in otherwise dark plumage of their torso and underwings.
One more fine point: Bald eagles have unfeathered legs, while golden eagle have legs protected
by feathers. When one considers their individual lifestyles, this adaptation makes sense. Fish-hunters
benefit from keeping their feet dry, while birds of the tundra and mountains can use additional insulation. |
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