Golden eagles
are found in the northern regions of North America, Europe, and Asia.
Six subspecies of
golden eagles share this global range but only one, Aquila chrysaetos
canadensis, makes its home in North America.
North American,
or Nearctic, golden eagles are widely distributed across Alaska, Canada,
the western U.S., and Mexico. Populations in the eastern United States
declined as human activities increased in this region.
Populations of golden
eagles above 55 degrees north latitude are migratory. These eagles nest
and raise their young in the north during the summer and move to milder
southern climates in the winter.
While Alaska boasts
a population of bald eagles greater than that in all of the other 49
states combined, the mountainous regions of Denali National Park, especially
north of the Alaska Range, are much better suited to golden eagles.
Bald eagles are found in Denali, but primarily on the south side of
the Alaska Range along waterways and lakes.
Golden eagles inhabit
open and mountainous areas over most of their range, hunting in landscapes
dominated by short vegetation and restricted tree cover.
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Golden
eagle low contour flying in Denali National Park & Preserve.
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Utilizing hunting
techniques such as soaring, still perching, and low contour flying,
golden eagles combine acute vision, power, speed, and agility to capture
and kill their prey. Factors such as weather conditions, escape response
of the prey, topography, and experience of the bird determine the hunting
strategy used by a golden eagle.
Throughout the Northern
Hemisphere, golden eagles are the preeminent diurnal (daytime) predator
of medium-size birds and mammals in open country.
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| Hoary
marmot scanning the terrain. |
In Denali, golden
eagles prey primarily on ptarmigan, snowshoe hare, arctic ground squirrel,
hoary marmot, and carrion. Additional prey includes pine martin, porcupine,
Dall sheep lambs, caribou calves, red fox, beaver, muskrat, smaller
mammals (such as voles), and a variety of birds.
Golden eagles rarely
eat fish.
Golden eagles in
Denali are largely unaffected by predation. Nests are usually inaccessible
to ground predators and golden eagles will defend their young from terrestrial
predators and other raptors.
Golden eagles spend
mid-March to late September in Denali. Territorial pairs reunite, breed,
and raise their young. While traditional nesting areas are used for
many years, whether or not the same pairs remain together over their
lifetime and use the the same nesting area each season is unknown.
We estimate that there are 125 territorial pairs of golden eagles living
in and near the boundaries of Denali.
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| Side
view of an empty nest. |
Golden eagles in
Denali usually build their nests on cliffs or rock outcroppings, although
a few nests are in trees just north of Denali. The nests can be as large
as 5 feet square or as small as 1 1/2 feet wide and consist of sticks
lined with grasses, lichen, and feathers.
Most nests are decades,
sometimes centuries, old and are repaired and reused through the years.
Eagles build multiple
nests in their territories and alternate use among them from season
to season.
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| Golden
eagle nestlings. |
Most pairs of eagles
complete their clutches of 1 to 3 eggs by early to mid-April in Denal.
Hatching occurs 45 days later in mid-May to early June.
The number of pairs
that successfully lay eggs in Denali varies annually. More eagles lay
eggs when snowshoe hare and willow ptarmigan are numerous and less lay
eggs when these early season prey populations are low.
Eaglets take their
first flight about 70 days after they hatch (usually by early August).
Males may fledge a few days earlier than females.
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| Golden
eagle fledgling. |
Fledglings make
their first southern migration in late September, leaving Denali independent
of their parents and their siblings.
Most juvenile golden
eagles from Denali complete their first migratory journey south in about
6 weeks.
Golden eagles from Denali
winter as far east as Kansas and South Dakota, as far south as northern
Mexico, and as far west as central Washington.
Subadult eagles
(one to four years old) are not seen in Denali in great numbers. Exposure
to territorial adult eagles aggressively defending nest sites is a significant
threat to the younger, inexperienced eagles. Most returning subadults
spend their summers spread across northern and interior Alaska.
Only 10 to 15% of
the eaglets that leave nests in Denali will live to reach sexual maturity
at about five years of age. Most will die due to starvation, disease,
predation, and electrocution. Unfortunately, deaths occasionally occur
due to illegal shooting. Golden eagles that survive through their younger
years may live 25 to 35 years in the wild.
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| Habitat
alteration and destruction is the greatest threat to golden eagles. |
Overall, the greatest
threat to golden eagles in North America is the alteration and destruction
of native habitats. These changes are causing a ripple effect of problems
for entire ecosystems and are likely to have detrimental effects on
golden eagle populations nesting and wintering in the western United
States.
The future of golden
eagles and many other species of migratory birds depends on our ability
to conserve important breeding, migratory, and wintering habitats and
the resources within these areas.
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| A
golden eagle soaring in the clouds over Denali National Park and
Preserve. |
Adult golden eagles
have a wingspan of more than 2 meters (over 6 feet) and are often seen
soaring on thermals for long periods of time without any apparent movement
of their wings.
Adult plumage is
predominately uniform dark brown. The tips of the tail feathers are
very dark and form a band at the end of the tail. The hackles (feathers
on the back of the neck and head) range in color from deep gold to pale
blonde and are the reason these eagles are called golden eagles.
The legs of Golden
Eagles are feathered to their feet.
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| Silhouette
of an adult golden eagle still perched on a rock outcropping. |
Female golden eagles
are considerably larger than males. Their wing-length is nearly 10%
longer and they outweigh their male counterparts by 40 to 50%. The average
male eagle weighs 3500 grams and the average female weighs 5000 grams
(8 and 11 pounds respectively).