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golden eagle

Aquila chrysaetos

What do they look like?

Golden eagles are North America's largest predatory bird. They are dark brown raptors with long, broad wings. Their length ranges from 70 to 84 cm, and their wingspan ranges from 185 to 220 cm. Males and females look similar, but females are much larger than males. Females weigh from 3940 to 6125 g. Males weigh from 3000 to 4475 g. Adults are mostly dark brown. They have a grayish brown tail and golden brown on their heads. Adults have dark brown eyes. Their bills and claws are black and their ceres and feet are yellow. Their legs are covered in feathers all the way down to the toes.

Juvenile golden eagles look similar to adults, but they have light patches on the tips of their wings, and a wide white band on their tails. They begin to look like adults when they are 4 to 6 years old.

There are 5 or 6 subspecies of the golden eagle. Only one subspecies, Aquila chrysaetos canadensis is found in North America. (Kochert, et al., 2002)

  • Sexual Dimorphism
  • female larger
  • Range mass
    3000 to 6125 g
    105.73 to 215.86 oz
  • Range length
    70 to 84 cm
    27.56 to 33.07 in
  • Range wingspan
    185 to 220 cm
    72.83 to 86.61 in
  • Average basal metabolic rate
    4.9929 W
    AnAge

Where do they live?

Golden eagles (Aquila chrysaetos) have a Holarctic distribution. They occur throughout Eurasia, in northern Africa, and in North America. In North America, golden eagles are found in the western half of the continent, from Alaska to central Mexico, with small numbers in eastern Canada and scattered pairs in the eastern United States. (Kochert, et al., 2002)

What kind of habitat do they need?

Golden eagles live in open and semi-open habitats from sea level to 3600 m elevation. They can be found in habitats such as tundra, shrublands, grasslands, woodland-brushlands, and coniferous forests. Most golden eagles are found in mountainous areas, but they also nest in wetland, riparian and estuarine habitats. (Kochert, et al., 2002)

  • Range elevation
    0 to 3600 m
    0.00 to 11811.02 ft

How do they reproduce?

Golden eagles are monogamous, and pairs may breed together for several years. In sedentary populations, pairs stay together year round. Golden eagle courtship includes the pair flying together, chasing, diving and pretending to attach each other. (Kochert, et al., 2002)

Golden eagles breed between March and August. Some golden eagles are sedentary, remaining in the same territory all year. These eagles may begin building their nests and forming pairs as early as December. Migratory golden eagles don’t begin pair formation and courtship until they return to the breeding grounds in early spring. Many pairs re-use the same nest for many years. Golden eagles usually build their nests on cliffs, but may also use trees, riverbanks and man-made structures, such as windmills, observation towers, nest platforms, and electrical towers. Nests are built 0 to 107 m off the ground. The male and female both build the nest. This takes 4 to 6 weeks. Nests are made of sticks and lined with soft vegetation, such as grasses, dry yucca leaves, inner bark, dead and green leaves, mosses and lichens. Some golden eagle nests are huge. The largest nest was 6.1 m tall and 2.59 m wide.

The female lays 1 to 4 (usually 2) eggs. She lays one egg every 3 to 4 days. The female incubates the eggs for 35 to 45 days (average 42 days). The chicks hatch several days apart, and are helpless (altricial). The older nestlings are usually much larger than the younger nestlings, and the older, stronger eaglets often kill the smaller chicks. The female parent broods the chicks regularly for up the first 45 days or so. Both parents bring food to the nestlings. The nestlings begin to leave the nest when they are 45 to 81 days old. They first leave the nest by walking, hopping or falling out of it. They begin to fly when they are about 10 weeks old, and become independent from their parents 32 to 80 days after fledging. Golden eagles begin to breed when they are 4 to 7 years old. (Kochert, et al., 2002)

  • How often does reproduction occur?
    Golden eagles breed once yearly.
  • Breeding season
    Golden eagles breed from March through August, depending on their geographic location.
  • Range eggs per season
    1 to 4
  • Average eggs per season
    2
  • Average eggs per season
    2
    AnAge
  • Range time to hatching
    35 to 45 days
  • Average time to hatching
    42 days
  • Range fledging age
    45 to 81 days
  • Range time to independence
    32 to 80 days
  • Range age at sexual or reproductive maturity (female)
    4 to 7 years
  • Range age at sexual or reproductive maturity (male)
    4 to 7 years

The female golden eagle of a pair does most of the incubation. She also broods the chicks much of the time for the first 45 days after hatching. Both parents bring food to the nest, but the male provides more food than the female. (Kochert, et al., 2002)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

How long do they live?

The oldest known golden eagle lived to 46 years in captivity. In the wild, golden eagles have been known to live up to 32 years. (Kochert, et al., 2002)

  • Range lifespan
    Status: wild
    48 (high) years
  • Range lifespan
    Status: captivity
    46 (high) years
  • Average lifespan
    Status: wild
    340 months
    Bird Banding Laboratory

How do they behave?

Some golden eagles are sedentary, and others are migratory. In North America, most golden eagles in Alaska and Canada migrate south in autumn. Most pairs that breed in the continental U.S. and southern Canada stay in the same area year-round.

Golden eagles are usually solitary or in pairs. However, young golden eagles may be found in groups. Adults may also group together in winter when the weather is very cold, or there is a lot of food available.

Golden eagles can carry up to 8 pounds while flying. They can fly up to 80 mph, and may reach 200 mph while diving. They fly with slow, powerful wingbeats. (Kochert, et al., 2002)

  • Range territory size
    22 to 33 km^2

Home Range

Golden eagle home range sizes vary with season and quality of habitat. During the breeding season, golden eagles in the western U.S. have home ranges from 20 to 33 square kilometers. Breeding pairs defend the boundaries of their home range with flight displays. (Kochert, et al., 2002)

How do they communicate with each other?

Golden eagles are mostly silent, except during the breeding season. They use nine different calls to communicate. Most calls appear communicate about food. Golden eagles don't use vocalizations to mark their territory. Instead, they mark the edges of their territory by flying around them. (Kochert, et al., 2002)

What do they eat?

Golden eagles mostly eat small mammals such as rabbits, hares, ground squirrels, prairie dogs, and marmots. They also eat some birds, reptiles and fish. Sometimes, golden eagles capture large prey, including seals (Phocoidea), ungulates, coyotes and badgers. They have also been known to capture large flying birds such as geese or cranes.

A pair of eagles will often hunt together. One chases the prey until it is exhausted, then the other swoops down to kill it. Golden eagles don’t usually store prey to eat later. (Kochert, et al., 2002)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • birds
  • mammals
  • reptiles
  • fish

What eats them and how do they avoid being eaten?

Golden eagles have few predators. There is no record of predation of golden eagle eggs, and few records of adult or nestling predation. Wolverines and grizzly bears are the only recorded predators of golden eagle nestlings. (Kochert, et al., 2002)

What roles do they have in the ecosystem?

Golden eagles impact the populations of the animals that they prey on. They may also compete with other species for prey and habitat, including bald eagles, coyotes, California condors, and white-tailed eagles. They also probably compete with other large birds for habitat. These other birds common ravens, gyrfalcons, peregrine falcons, rough-legged hawks and other species. (Kochert, et al., 2002)

Do they cause problems?

Golden eagles occasionally kill livestock, costing ranchers money.

How do they interact with us?

Some researchers suggest that golden eagles are beneficial to livestock production because they eat a large number of rabbits, which compete with livestock for forage.

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

The golden eagle is federally protected under the Bald Eagle Protection Act of 1962. In some parts, a decline of golden eagle populations has been recorded. Washington and Montana list it as a species of special concern; and Maine, New Hampshire and New York recognize it as an endangered species. But in other areas they are common and populations are presumably stable. (Tesky, 1994)

Previous to the Protection Act of 1962, some 20,000 golden eagles were killed, mostly from aircraft, because they were thought to prey on yound sheep and goats. But studies in towns where sheep are raised found no evidence to support such claims, as almost 70% of the eagle diet consisted of rabbits. Many golden eagles have been electrocuted in power lines, caught in steel traps set for coyotes and other animals, and poisoned by ranchers. Direct and indirect human-caused mortality, disturbance and elimination of prey by habitat alteration are the main factors limiting golden eagle populations. Recreational activites may also disturb breeding, migration and wintering activities. Golden eagles are likely to abandon nests during incubation if they are disturbed. (Terres, 1980; http://www.fs.fed.us/database/feis/animals/Bird)

Some more information...

Golden eagles are sometimes called the American War Bird or the Bird of Jupiter (Terres, 1980).

Contributors

Kari Kirschbaum (author, editor), Animal Diversity Web.

Alicia Ivory (author), University of Michigan-Ann Arbor.

References

Reilly, E. The Audubon Illustrated Handbook of American Birds. McGraw-Hill Book Company, New York, 1968.

Terres, John. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knoph, New York, 1980.

"The Raptor Center, University of Minnesota College of Veterinary Medicine" (On-line). Accessed (Date Unknown) at http://www.raptor.cvm.umn.edu/.

Kochert, M., K. Steenhof, C. McIntyre, E. Craig. 2002. Golden Eagle (Aquila chrysaetos). Pp. 1-44 in A Poole, F Gill, eds. The Birds of North America, Vol. 684. Philadelphia: The Birds of North America.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Ivory, A. 2002. "Aquila chrysaetos" (On-line), Animal Diversity Web. Accessed September 30, 2014 at http://www.biokids.umich.edu/accounts/Aquila_chrysaetos/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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