Quote: “In the golden eagle I see what it is to be strong, wild and free. What it means to have hope, energy and opportunity. Enjoy these birds and their evocative haunts, and as you glimpse this kind of bird, or find its feather cast from the heavens, whisper a word of thanks.” Jeff Watson, The Golden Eagle (2010).
The Golden Eagle occurs across portions of the Northern Hemisphere and is one of the largest species of raptors in North America. They are long lived (20-30 years), slow reproducing, and exhibit delayed sexual maturity with individuals usually not joining a breeding population until they are at least four years of age. Golden eagles occur regularly throughout the Brooks Range region primarily from late winter through mid-autumn, which is the breeding season for this species in Alaska. Some individuals may overwinter in the Brooks Range, but most eagles depart the area in autumn and spend the winter at lower latitudes.
Birds that occupy nesting territories or who are seeking entry into the breeding population return to the Brooks Range from early March to early April. Birds who are not territory holders and who are not seeking entry in the breeding population return later, often as late as mid-June. Non-territorial golden eagles are not tied to a nesting territory during the breeding season and often return to the Brooks Range much later than the territorial eagles. Their movement patterns are also very different than the territorial birds and they often roam great distances during the breeding season, apparently in search of food in places where they can avoid aggressive encounters with territorial eagles. For example, many non-territorial golden eagles spend the summer north of the Brooks Range on Alaska’s Arctic Coastal Plain, where they find an abundance of food resources.
Golden eagles are highly efficient fliers and predators. They exhibit tremendous variability, speed and maneuverability in flight and put those skills to good use when hunting. They prey on a diversity of species including snowshoe hare, ptarmigan, arctic ground squirrel, hoary marmot, and they scavenge carrion. Eagles often seek out live prey during the nesting season when they are feeding their nestlings.
In years when they are nesting, a mated pair of golden eagles will begin their courtship as soon as they arrive on their territory. They arrive at a time when prey resources are limited, and many golden eagles will not lay eggs if prey abundance is low when they arrive on their territory. During this time of year, eagles prey mainly on snowshoe hare and ptarmigan, both species who exhibit strong cyclic patterns in abundance. When prey abundance is low, eagle pairs will defend their territory but will not attempt to raise offspring. If sufficient prey is available, the female will lay one to three eggs by mid-April and do much of the incubation over the next 40 to 45 days. If her mate is a good provider, she will remain on the nest keeping the eggs safe during extreme weather events such as the extremely low temperatures and massive blizzards that are common in the Brooks Range in spring.
After the nestlings hatch, the female broods them while the male provides food for her and the nestlings. Their diet expands when arctic ground squirrel and hoary marmot emerge from hibernation and young of those species emerge from their natal burrows. When the nestlings reach about 21 to 28 days of age, the female will start spending more time away from the nest and may join the male on hunting trips. During Alaska’s short summer, the nestlings develop rapidly, growing from tiny down-covered, fist-sized nestlings to nearly full-grown eagles in just about 70 days. Their parents spend the summer hunting and it is highly likely that much of the nestling’s energetic needs are fulfilled by the juvenile arctic ground squirrels killed and brought to the nest. By mid-August, most nestlings have fledged (left the nest) and are starting to hone their flying skills. Over the next four to six weeks, the parent eagles will continue to protect their offspring, but the offspring will start hunting on their own and improve their flying skills. By mid-September, the fledglings will embark on their first autumn migration, independent of their parents and their siblings. Over the next two months they will travel alone over some of the most spectacular, rugged, and remote terrain in western North America.
Golden Eagle abundance in North America.
Fink, D., T. Auer, A. Johnston, M. Strimas-Mackey, O. Robinson, S. Ligocki, W. Hochachka, C. Wood, I. Davies, M. Iliff, L. Seitz. 2020. eBird Status and Trends, Data Version: 2019; Released: 2020. Cornell Lab of Ornithology, Ithaca, New York.
Katzner, T. E., M. N. Kochert, K. Steenhof, C. L. McIntyre, E. H. Craig, and T. A. Miller (2020). Golden Eagle (Aquila chrysaetos), version 2.0. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi-org.arlis.idm.oclc.org/10.2173/bow.goleag.02
