Golden Eagle (Aquila chrysaetos)
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.
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.
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.
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.
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.
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.
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.
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.
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).
Denali Golden Eagle Study: Publication List (February 2015)