GOLDEN EAGLE

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The Golden Eagle is one of the largest, fastest, nimblest raptors in North America. Lustrous gold feathers gleam on the back of its head and neck; a powerful beak and talons advertise its hunting prowess. You're most likely to see this eagle in western North America, soaring on steady wings or diving in pursuit of the jackrabbits and other small mammals that are its main prey. Sometimes seen attacking large mammals, or fighting off coyotes or bears in defense of its prey and young, the Golden Eagle has long inspired both reverence and fear.

COOL FACTS

• Although capable of killing large prey such as cranes, wild ungulates, and domestic livestock, the Golden Eagle subsists primarily on rabbits, hares, ground squirrels, and prairie dogs.
• The Rough-legged Hawk, the Ferruginous Hawk, and the Golden Eagle are the only American hawks to have legs feathered all the way to the toes.
• The amount of white in the wings of a young Golden Eagle varies among individuals, and a few lack white in the wings entirely.
• The Golden Eagle is the most common official national animal in the world—it's the emblem of Albania, Germany, Austria, Mexico, and Kazakhstan.
• Golden Eagles and their feathers are crucial to the beliefs and ceremonies of many Native American cultures. Members of the Hopi tribe remove nestlings, raise them in captivity, and sacrifice them when they are fully feathered. Since 1986, the U.S. Fish and Wildlife Service has issued a permit allowing the Hopi to conduct these activities legally.
• Because their common prey animals (mammals) don’t tend to ingest pesticides, Golden Eagles have escaped the harm sustained by fish-eating or bird-eating raptors from DDT and related chemicals. When these pesticides thinned the eggshells of many birds of prey, Golden Eagles’ shells retained normal thickness. Pesticide concentrations in their blood stayed below levels known to cause reproductive problems.
• Biologists, engineers, and government officials have cooperated in developing and publicizing power-pole designs that reduce raptor electrocutions—caused when the large birds' wings or feet accidentally touch two lines and form a circuit. Since the early 1970s, utility companies have modified poles to prevent eagle electrocutions. And some new power lines in nonurban areas have been built to “raptor-safe” construction standards.
• “Hacking,” an age-old falconry technique, is helping rebuild Golden Eagle populations. Humans feed caged, lab-reared nestlings at a nestlike hack site until the birds reach 12 weeks old, when the cage is opened and they begin feeding themselves. The fledglings continue to receive handouts from their hack-site caretakers for several weeks, until they gain full independence in the wild.

HABITAT

Golden Eagles live in open and semi-open country featuring native vegetation across most of the Northern Hemisphere. They avoid developed areas and uninterrupted stretches of forest. They are found primarily in mountains up to 12,000 feet, canyonlands, rimrock terrain, and riverside cliffs and buffs. Golden Eagles nest on cliffs and steep escarpments in grassland, chapparal, shrubland, forest and other vegetated areas.

FOOD

Golden Eagles prey mainly on small to medium-sized mammals, including hares, rabbits, ground squirrels, prairie dogs, and marmots. Black-tailed jackrabbits are a key prey species throughout much of their range. These eagles are also capable of taking larger bird and mammal prey, including cranes, swans, deer, and domestic livestock. They have even been observed killing seals, mountain goats, bighorn sheep, pronghorn, coyotes, badgers, and bobcats. In addition to live prey, Golden Eagles often feed on carrion, following crows and other scavengers to a meal. They also catch fish, rob nests, and steal food from other birds.

NESTING

NEST DESCRIPTION

Starting 1–3 months before egg-laying, a Golden Eagle pair builds a nest of sticks and vegetation—sometimes also including bones, antlers, and human-made objects such as wire and fence posts. They line the nest with available vegetation, such as yucca, grasses, bark, leaves, mosses and lichens, or conifer boughs. They include aromatic leaves, possibly to keep insect pests at bay. Resident birds continue adding nest material year-round, reusing the same nest for multiple seasons and sometimes alternating between two nests. Nests are huge, averaging some 5-6 feet wide, and 2 feet high, enclosing a bowl about 3 feet by 2 feet deep. The largest Golden Eagle nest on record was 20 feet tall, 8.5 feet wide.

NEST PLACEMENT

Golden Eagles usually nest on cliffs. They may also build nests in trees, on the ground, or in human-made structures, including windmills, observation towers, nesting platforms, and electrical transmission towers. Constructed near hunting grounds, Golden Eagle nests often command a wide view of their surroundings.

NESTING FACTS

Clutch Size

1–3 eggs

Number of Broods

1 broods

Egg Length

2.7–3.4 in
6.8–8.6 cm

Egg Width

1.9–2.5 in
4.9–6.4 cm

Incubation Period

41–45 days

Nestling Period

45–81 days

Egg Description

White to cream or pale pink, usually with small brown blotches.

Condition at Hatching

Weak, weighing about 3 oz; partially covered with grayish-white down; eyes partially open.

BEHAVIOUR

Golden Eagles possess astonishing speed and maneuverability for their size. Diving from great heights, they have been clocked at close to 200 miles per hour. In an undulating territorial and courtship display known as “sky-dancing,” a Golden Eagle performs a rapid series of up to 20 steep dives and upward swoops, beating its wings three or four times at the top of each rise. In “pendulum flight,” the eagle dives and rises, then turns over to retrace its path. Single birds and pairs engage in aerial play with objects such as sticks or dead prey, carrying these items high into the sky, then dropping and retrieving them. In addition to attacking prey from the air, Golden Eagles sometimes hunt on the ground, wildly flapping as they run. Mated pairs hunt jackrabbits cooperatively during breeding season—one eagle diverting the animal’s attention while the second makes the kill.

CONSERVATION

In 1962, the U.S. Bald and Golden Eagle Protection Act outlawed harming these birds, their eggs, and their nests. Although this legislation remains in effect, humans are still Golden Eagles’ greatest threat: it's estimated that more than 70 percent of recorded Golden Eagle deaths are attributable to human impact, either intentional or inadvertent. Some sheep ranchers trapped, shot, or poisoned the birds into the 1980s. Some eagles have died after eating poisoned prey animals set out to control coyotes. Others succumb to lead poisoning from ammunition in hunter-shot prey. Most recorded deaths are from collisions with vehicles, wind turbines, and other structures or from electrocution at power poles (newer designs have been developed that, if used, can greatly reduce this risk). Urbanization, agricultural development, and changes in wildfire regimes have compromised nesting and hunting grounds in southern California and in the sagebrush steppes of the inner West. Golden Eagles did not prove as susceptible to poisoning from the pesticide DDT as other large raptors, probably because of their diet of mammals. The species persists, but populations in the western U.S., particularly those near urban areas, have declined.

SOURCE CREDITS

• The Cornell Lab of Ornithology
• Kochert, M. N., K. Steenhof, C. L. McIntyre, and E. H. Craig. 2002. Golden Eagle (Aquila chrysaetos). In The Birds of North America, No. 684 (A. Poole and F. Gill, eds.). The Birds of North America Online, Ithaca, New York.
• Dunne, P. 2006. Pete Dunne’s Essential Field Guide Companion. Houghton Mifflin, New York.
• Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The Birder’s Handbook. Simon & Schuster, New York.
• Sibley, D. A. 2003. The Sibley Field Guide to the Birds of Western North America. Knopf, New York.