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Aquila chrysaetos

(White-Tailed Eagle)

Common Names

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Click on the language to view common names.

Common Names in Dutch:

Steenarend

Common Names in English:

American War Bird, Bird of Jupiter, Black Eagle, Brown Eagle, Calumet Bird, Calumet Eagle, Canadian Eagle, Golden Eagle, Gray Eagle, Jackrabbit Eagle, King of Birds, Mountain Eagle, Ring-Tailed Eagle, Ringtail, Royal Eagle, War Bird, White-Tailed Eagle

Common Names in French:

Aigle Royal

Common Names in German:

Steinadler

Common Names in Hebrew:

עיט זהב

Common Names in Italian:

Aquila Reale

Common Names in Japanese:

イヌワシ

Common Names in Russian:

Berkut, Беркут

Common Names in Spanish:

guila Real, Águila Real

Description

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Physical Description

Adult : Head : Crown: tawny gold Face : Cere: yellow Facial Skin : yellow Bill: black Neck: Nape: tawny gold Sides: tawny gold Legs : Notes : feathered tarsus.

Color:

Adult : Golden feathering on nape · Plumage almost entirely dark brown, without white in underwing coverts · Two pale brown median tail bands · Golden band on upperwing coverts

Immature : Plumage almost entirely dark brown · White bases to outer secondaries and inner primaries produces oval , white patch · White tail with broad, crisp , dark terminal band

Subadult : Plumage gradually darkens to resemble that of adult, with white in wings disappearing

Size/Age/Growth

About 35 to 38 inches long, with a wingspan of 72 to 96 inches. Adults weigh about 56 ounces .

Habitat

Solitude and the golden eagle seem to go hand in hand. Open country is the preferred habitat but it can be found over forests during migration. Arid , sloping valleysides, benchlands or flatlands cut by canyons , gullies or rock outcrops are preferred over flat, featureless terrain. Tundra and alpine country, deserts, southern coastal areas, eastern bogs , logged openings, grasslands, and early seral stages of forested lands , are all used. Thick, extensive areas of coniferous forests are usually avoided, except perhaps by birds of passage . Cliffs with ledges for nesting are an important part of the summer habitat, but trees will also be used as nest sites. In general, hilly or mountainous terrain is preferred over flatlands due in part to the advantageous lift gained from the air currents over broken terrain. Winter habitats include the arid, shrub-steppe country of the mid-western states and in general are similar in physical appearance to the summering areas. During migration, mountain ridges are preferred in order to benefit from drafts and other air currents. Key attributes of the habitats include nesting cliff ledges or large trees, perches such as large trees, knolls or large rocks, and broken terrain subject to varied air currents providing lift.

Vegetation: northern temperate grasslands, arid montane scrubs, arid lowland scrubs • Maximum Elevation: 2,700 meters • Foraging Strata: Terrestrial • Center of Abundance: Upper subtropical: higher slopes, 500-1,600 m.; subtropics. • Sensitivity to Disturbancet: Medium

Typically found at an altitude of 0 to 3,632 meters (0 to 11,916 feet).[1]

Ecology: List of Habitats : 1.1 Forest - Boreal 1.4 Forest - Temperate 3.5 Shrubland - Subtropical/Tropical Dry 3.7 Shrubland - Subtropical/Tropical High Altitude 3.8 Shrubland - Mediterranean-type Shrubby Vegetation 4.4 Grassland - Temperate

Biology

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Diet

On average, an adult eagle consumes eight to 12 ounces (227 to 340 grams ) of food per day throughout the year. Consumption is not likely to be consistent each day, with periods of gorging versus fasting, depending upon availability of prey . Winter consumption is likely greater than during the summer.

In terms of total biomass , the principal foods of golden eagles are rodents, hares and rabbits - black-tailed jackrabbits in the NCA. The mammalian component of eagle diets as noted from many studies, varies from 70 to 97 percent, with birds variably being another major component. A review of North American literature revealed that 52 species of mammals, 48 birds, five reptiles and two fishes have been recorded in the diets of the golden eagle. Insects, such as the Mormon cricket, are also documented as a prey item.Specifically, some species documented include black-tailed jackrabbit, white-tailed jackrabbit, Nuttall's cottontail, yellow-bellied marmot, hoary marmot, arctic ground squirrel, ground squirrels (Spermophilus species), prairie dog, snowshoe hare, mule deer, white-tailed deer, Dall sheep (lambs), pronghorn (fawns), young mountain goats, mountain sheep and mountain caribou, livestock (young or carrion ), red fox, arctic fox (young), coyote, opossum, skunk, red squirrel, muskrat, mink, woodchuck, wood rat , microtines, deer mice, whooping crane, wild turkey, trumpeter swan, great blue heron, ptarmigan, grouse, pheasant, gray partridge, chukar, sage grouse, horned lark, red-tailed hawk, broad-winged hawk, barred owl, common raven, common crow, common loon, American bittern, black duck, various snake species (particularly gopher snakes), horned lizard, leopard frog , box turtle, and fish such as suckers and perch. Carrion is also eaten and includes a wide range of species including domestic animals that died for reasons other than eagle attack.Much has been written about golden eagle attacks on domestic stock. That such depredation occurs is undoubtedly true, but the degree depends upon the availability of natural food supply, ranching practices, weather, and a variety of other factors . Sound animal management practices reduce the losses to eagles to very low levels.

The wing beat of the golden eagle is slow and ponderous in nature. It is more shallow than that of the bald eagle. Soaring golden eagles hold their wings flat or in a slight dihedral , suggestive of turkey vultures. It is the soaring flight that is seen so frequently. Because of its heavy reliance on mammals for food, the golden eagle hunts both early in the day or late in the afternoon, corresponding with peaks of activity in its food supply. During the nesting season , hunting will certainly go on all day as the demands of the young increase. These eagles will gorge and then fast for days, thus enabling them to survive brief periods of limited food supply. Kills are often made in areas of updraft winds, allowing birds heavily weighted with prey to take off after making the kill or gorging heavily. The hunting tactics can be grouped into the following ten strategies:

Perch and Wait - elevated sites are used to search the terrain. Perches include trees , power poles , rock bluffs , fences and so forth. Ground Perching - occasionally, perching on a mound or low rock is used, followed by a flying attack once the prey is spotted Low Level Flight - birds will fly quickly or slowly, low over the terrain, often changing direction and surprising their quarry. This technique is particularly useful over open terrain where the air currents and vagaries of the landscape are used to their advantage. High Level Flight - this is primarily soaring above the ground at varying heights and descending rapidly to make the strike . Aerial Attack - other birds will be attacked in mid flight. Flushing - this consists of wing flapping, screaming, and walking around bushes or other places where prey is known to be hiding. Cooperative Hunting - two birds will use a variety of the above styles to flush prey towards the partner who will then make the final strike. Piracy - eagles have been seen robbing food from one another or from other raptors . They have also snatched ground squirrels flushed by humans walking across a pasture. Carrion Eating - the golden eagle has been observed feeding on carcasses along with bald eagles, ravens, crows and magpies. Strike, Kill, and Consumption - the approach to the prey may be with flapping flight or a descent followed by a rapid glide or combinations of these. The strike is often upwind and usually in areas of updrafts. As the quarry is reached, a foot is extended and the prey clutched tightly. The second foot may also be used. If the animal is small, it is simply lifted up and flight continues unabated. Larger animals may cause an abrupt halt to the flight as both eagle and prey struggle on the ground. The head is grabbed as quickly as possible and then the other talons are driven into the lungs or soft parts of the body, causing the animal to bleed to death or die from lack of oxygen. The beak is generally not used for killing or fighting with the prey. Once all struggling has ceased, the prey is torn apart with the beak.

The home ranges are large and defense would be impossible. However, individual nest sites are spaced apart and maintained with the use of some of the aforementioned flight behavior. Aerial attacks are also made in order to drive away intruders if they venture too close to the nest.During the nesting season, territorial defense is evident. Bald eagles will be escorted or chased from the nesting area. At other times such as in winter, bald and golden eagles may share the same roost tree and will certainly tolerate one another when gorging at large carcasses. Golden eagles are felt to be dominant in carrion-feeding situations. Nesting golden eagles seldom tolerate the presence of another raptor nest, close to their own nest and may opportunistically kill them during encounters . Nests as close as 0.7 miles (1.1 kilometers) apart have been documented, but internest distances of up to 6 miles (9.6 kilometers) have been documented. In the NCA most golden eagle nest about 3-4 miles apart. Golden eagles are felt to be wary and shy of human beings and will tend to avoid contact

Reproduction

Although the flight displays of the Golden Eagle resemble those of buteos, the relationship to courtship is rather less certain. The following displays have been described and may have some function in terms of maintaining the pair bond or territorial defense:

Copulation occurs occasionally when the purpose is clearly not for reproduction . Clutches may be laid and incubation underway such that the purpose of the act may be to maintain the pair bond, amongst other things.Human disturbance around nests has been frequently documented as the cause for nest failure. From recoveries of dead, banded birds, the average length of life was about 20 months, and the oldest bird lived for 11 years. Other studies have shown that birds found dead ranged in age from four months to four years. Mortality is highest amongst young birds, and the prime reason is assumed to be inexperience. In Scotland, it was shown that 75 percent of eagles were dead before reaching sexual maturity. Thus, it takes a pair of adults 10 years to produce enough young to replace themselves, and the North American situation has been considered comparable. Captive birds have laid eggs up until their 28th year and have lived as long as 48 years.Mortality in nestlings has been caused by nest abandonment by the adults, human disturbance, heat stress, trichomoniasis, falling out of the nest, falling rocks and death by sibling attack. Mortality in flying birds has been caused by shooting, poisoning , electrocution , predation , disease and accidentally being caught in traps for fur-bearing mammals. Shooting eagles to protect livestock undoubtedly continues today, but historically, this practice accounted for the loss of many thousands of birds. There is extensive documentation of eagle bounties, attempts at extermination, shooting from aircraft, and general persecution. Statistics show that in parts of Texas alone, at least 1000 eagles per year were killed for a period of 20 years, and in other parts of the west, similar numbers seem likely. In British Columbia, in 1922 alone, over 7,000 eagles were shot for bounty money. Many were likely bald eagles, but golden eagles undoubtedly were also victims

Nest sites may be on cliff faces , dirt banks, in deciduous or coniferous trees , on the ground or on man-made structures. The choice of location varies geographically and clearly depends upon the availability of certain features. Cliff faces and large trees are the most commonly-used nest sites and some pairs will alternate between the two types . Where possible, sites which avoid either excessive heat or excessive cold are chosen. Southerly-facing sites at northern latitudes are warmer and northerly-facing sites at southern latitudes are cooler and there is some evidence to indicate that there are preferences shown where the opportunity arises. Tree nests are often near the edges of openings such as fields or clear cuts . Nest sites may be used for many years by a succession of occupants.

Typically, the nest is comprised of large, dry sticks that are gathered from the ground or may be broken from a tree. The nest lining material varies geographically but it is of much finer material than the structural items. Rootlets , eucalyptus leaves, moss, rabbit fur, shrub twigs , yucca roots , dried grass , and conifer branchlets have all been used to line nests. Curious items that have been incorporated into nests include cow bones, deer antlers, barbed wire, burlap bags , rags , paper and rubbish and even a hat. Nests vary in size but may initially be around three feet (0.9 meters) in diameter. Over the years, additions and repairs may result in nests as large as eight feet (2.4 meters) in diameter. The height may vary from several feet and beyond. The building of several nests is common with up to 12 nests being built by a single pair. Pairs averaged six nests in Idaho.The clutch size varies from one to five (rarely) and more typically two to three eggs. The eggs are about 3.1 inches (78.7 millimeters) long and 2.3 inches (58.4 millimeters) wide. The base color varies from white to cream and is variably spotted or blotched with browns, chestnut-red, or pale gray. Some may be almost unmarked and they are non-glossy. The laying interval is likely between 90 and 120 hours with incubation starting as the first egg is laid. Although the golden eagle is single-brooded, replacement clutches may be laid in the event of loss of the original. The interval before relaying varies from 24 to 28 days. Egg-laying may begin during February at the extreme southern parts of the range while in the north, egg production may not occur until mid-June. March and April are common months for laying by non-migratory birds.Incubation is primarily by the female with food being brought to her by the male. She feeds at a nearby plucking site. The male will relieve the female for periods during the afternoon but she probably does all of the incubating during the evening hours. Brooding of the young is by the female and occasionally by the male. Fresh greenery is brought to the nest by both sexes.The incubation period is from 41 to 45 days, although it is variably reported in the literature. Earlier estimates of 30 to 35 days were likely incorrect. The long interval between the laying of each egg leads to young of different sizes. Fledging occurs at 72 to 84 days, but has been reported as 59 to 70 days. At about seven days, the nestling can sit up, stretch its neck and chirp for food. At 14 days, crawling is possible and the white down is well-developed. By 28 days, the chicks can waddle, hiss and raise their wings in threat displays. By 42 days, hostile threat capabilities are much better developed and the young can feed themselves. At 49 days, they will use both feet and wings in order to move around. By days 56 through 65, strength increases, mobility improves continually and vocalizations have become more complex . Mantling over prey is evident. The female sleeps away from the nest from about day 40 onwards. Siblicide (killing of ones brother or sister) is well-documented in the golden eagle, and it generally occurs when the young are less than 21 days old.Flying young remain dependent upon their parents for about 11 weeks after fledging. In migrant populations, the entire family may begin migration together whereas in more southerly resident populations, the young may remain well into the fall or winter near the parents' territory. The existence of what appear to be family groups on the winter range suggests that the families could stay intact until the start of the next breeding cycle .The breeding success for golden eagles is variable and probably follows major food source fluctuations. The number of young fledged per nest varies from 1.2 to 1.8 in different parts of the United States.

Migration

Some migrate

The vocalizations are limited and variously generalized as screams, yelps or yaps. When close to one another, the adults will utter slow yelps that have been phonetically described as "kee-yelp, che-owp"or "ki-ah." Single syllable "kleek" or mellow ''Culp'' sounds are described. The "culp" notes may be given by birds of all ages. Captive, restrained birds give a shrill "ki-ki-ki-ki" scream. "Kaa kaa kaa kaa culp culp culp" sounds may be given as adults approach the nest with food and shriller versions may be given by the eaglet in the nest. Over 5,000 "yelps" were given by one eaglet after being given food and before showing any interest in eating it. Screams have been described as low, rasping "kee-au-augh", while other vocalizations include cheeps, grunts , "boop" notes and clucky notes. One female was said to have sung a melodious song reminiscent of that of the wild turkey. Eaglet sounds are variations of the yelping and "ki-ki-ki-ki" notes of the adults, but at different pitches. Interestingly, different observers have used adjectives as disparate as "rather pathetic" to "real blistering serenades" to describe different vocalizations of the golden eagle.

Taxonomy

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Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 17-Oct-2001.

Similar Species

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Bald Eagle

Members of the genus Aquila

ZipcodeZoo has pages for 61 species and subspecies in this genus:

A. adalberti (Spanish Imperial Eagle) · A. albicans · A. albipes · A. amurensis · A. audax (Wedge-Tailed Eagle) · A. audax audax (Wedge-Tailed Eagle) · A. audax fleayi · A. braccata · A. buson · A. chrysaeetos · A. chrysaetos (White-Tailed Eagle) · A. chrysaetos canadensis (Golden Eagle) · A. chrysaetos chrysaetos (White-Tailed Eagle) · A. chrysaetos daphanea · A. chrysaetos fulva · A. chrysaetos homeyeri · A. chrysaetos japonica · A. chrysaetos kamtschatica · A. chrysaetos ssp · A. chrysaetus · A. clanga (Greater Spotted Eagle) · A. clangula · A. fulvescens · A. gurneyi (Gurney's Eagle) · A. hastata · A. heliaca (Spanish Imperial Eagle) · A. heliaca adalberti (Spanish Imperial Eagle) · A. heliaca heliaca (Spanish Imperial Eagle) · A. heliaca helica · A. leucorypha · A. maculata · A. megaloptera · A. milvoides · A. murina · A. naevioides · A. nipalensis (Steppe Eagle) · A. nipalensis nipalensis (Steppe Eagle) · A. nipalensis orientalis · A. orientalis · A. pennata (Scaleless Dragonfish) · A. pennatus · A. pezopora · A. picta · A. pomarina (Lesser Spotted Eagle) · A. pomarina hastata · A. pomarina pomarina (Lesser Spotted Eagle) · A. pomorina · A. rapax (African Tawny-Eagle) · A. rapax belisarius · A. rapax nipalensis · A. rapax orientalis · A. rapax rapax (African Tawny-Eagle) · A. rapax raptor · A. rapax vindhiana · A. raptor · A. sp · A. verreauxi · A. verreauxii (Verreaux’s Eagle) · A. vindhiana · A. wahlbergi (Wahlberg's Eagle) · A. wahlbergii

More Info

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Further Reading

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Notes

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Contributors

Identifiers

Footnotes

  1. Mean = 334.850 meters (1,098.589 feet), Standard Deviation = 577.260 based on 16,975 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 2009-12-02