The Golden Eagle is a large, dark, long-winged raptor that soars on flat or slightly up-tilted wings. In all ages except newly fledged juveniles, and especially in adult plumage, the nape feathers create a "golden" hue found in no other species of raptor. The sexes are similar, and in flight, the adults are essentially all dark with no light markings. The juveniles, immatures, and sub-adults resemble the adults in that they are large, dark raptors, but the base of the primaries and the base of the tail are boldly whitish and contrast markedly with the rest of the plumage. It is mainly a bird of the open country that prefers to nest on cliffs or in very large trees. It hunts largely by soaring and feeds on small mammals, birds, and carrion, and has been unjustifiably persecuted for allegedly causing great losses to the livestock industry through predation of young animals. The legs are feathered to the toes.
SIZE
The Golden Eagle is a large raptor exceeded in size in North America only by the California Condor and the Bald, Steller's, and White-tailed eagles. The female averages larger than the male but there is overlap in some measurements. Combined length measurements for males and females range from 30 to 40 inches (76.2 to 101.6 centimeters). The combined wingspread ranges from 60 to 80 inches (152.4 to 203.2 centimeters). Weights for males vary from 6.5 to 9.5 pounds (3.0 to 4.3 kilograms) with an average 8.6 pounds (3.9 kilograms) and females from 8 to 13 pounds (3.6 to 5.9 kilograms) with an average of 10.6 pounds (4.8 kilograms). Birds in their first year of life weigh as much as the adults.
MORPHS AND MOLTS
There are no color-morphs of Golden Eagle. There is however, a juvenile plumage followed by three or four "subadult", or pre-definitive plumages prior to the "adult", or definitive plumage developing. Incomplete molts result in various feathers always present from previous plumage generations such that some birds may never acquire pure, complete definitive feathering. The molt is prolonged and appears confusing, if not chaotic to understand in terms of the sequence of individual feather molt. For example, the primary flight feathers start molting from the innermost outward. After a few feathers are renewed, the molt ceases until the following year, beginning again where it left off, progressing outwards. Simultaneously, the molt can start again with the innermost primaries.
The juvenile plumage is acquired while the young are in the nest. It begins to appear about day 24 and covers the nestling by about day 56. The plumage is fully-grown by about 112 days. This plumage is retained throughout the winter and is then replaced by the first prebasic molt which begins at about month 11 and is prolonged. The first basic (immature) plumage is attained from spring into late summer of the year following hatching and is retained for about one year. The second basic plumage is attained from spring through late summer of the second year after hatching. It too is retained for almost one year. Birds in this plumage essentially look like adults. The third basic plumage is attained from spring through late summer of the third year after hatching and retained for one year. Again, it looks like the adult plumage. The fourth basic plumage is attained from spring through summer of the fourth year after hatching. This is the plumage that is repeated annually thereafter and is considered to be the first true definitive or "adult" plumage by some authors. Depending upon interpretation, the first true adult plumage is therefore not acquired until the fourth or fifth calendar year of life, even though by the third calendar year, birds may well look like adults in the field. The presence of earlier juvenile type feathers in this third year are difficult to detect under field conditions.
SPECIFIC DESCRIPTION
Apart from size differences, the plumage of the sexes are very similar.
Adult Male - Perched
HEAD
- crown and nape feathers are coppery-reddish fading to straw during the winter forming a "golden" cape
- sides of head and throat are deep brown
- the beak is tri-colored with a dark tip, horn colored base, and yellow cere
- the iris varies from yellowish to reddish brown; usually becomes paler with age
BODY
- body often appears mottled with old faded and new dark feathers
- the breast and abdomen are dark brown
- the undertail coverts are brown and perhaps reddish brown
- the back is brown but may appear somewhat variegated
WINGS
- the scapulars are brown to dark and the coverts more tawny which may give the impression of a lighter bar across the wing
- the primaries are black
- the wing tips do not reach the tip of the tail
TAIL
- the undertail is variable from grayed brown through dark brown and there may be fainter, lighter zig zag bands across the tail
- the upper tail is variable from grayed brown to dark with lighter zig zag bands; males have two to three narrow gray bands while females have two wide gray bands
LEGS
- the legs and tarsi are well feathered to the toes with light brown to white feathers that are distinctly lighter than the remaining underside
- the light brown buff or whitish feathers contrast with the underside of the body
- the feet are various shades of yellow and the talons are black
Adult Female - Perched
The female is essentially the same as the male except for size. There may be minor variations in the tail with the female having wider gray tail bands.
HEAD
- crown and nape feathers are coppery-reddish fading to straw during the winter, forming a "golden" cape
- sides of head and throat are deep brown
- the iris varies from yellowish to reddish brown
BODY
- the breast and abdomen are dark brown and mottled because of continued body molt of old and new feathers
- the undertail coverts are brown and perhaps reddish brown
- the legs and tarsi are well feathered with light brown to white feathers that are distinctly lighter than the remaining underside
- the back is brown but may appear somewhat variegated
WINGS
- the scapulars are brown to dark and the coverts more tawny which may give the impression of a lighter bar across the wing
- the primaries are black
- the wing tips do not reach the tip of the tail
TAIL
- the undertail is variable from grayed brown through dark brown and there may be fainter, lighter zig-zag bands across the tail
- the upper tail is variable from grayed brown to dark with lighter zig zag bands
- the posterior bands may be wider and more distinctive than in the males
LEGS
- the legs are feathered down to the foot and can reach the base of the toes
- the light brown, buff or whitish feathers contrast with the underside of the body
- the feet are yellow (various shades) and the talons are black
Immature (first year) - Perched
HEAD
- the crown is blackish, but the rear of the crown and nape are reddish brown and contrast with the rest of the head and back
- the sides of the head and throat are very dark brown
- the cere is yellow
- the iris varies from brown to hazel and lightens with age
BODY
- body is uniformly dark as no molt is present so all feathers appear uniform in color
- the breast and belly are generally a dark, sooty brown but some feathers may have light tips
- the undertail coverts are lighter and may be pale yellowish brown
- the back is blackish brown or sooty and may develop a purplish sheen, and the upper tail coverts are dark
WINGS
- the coverts are variably brownish and could fade even lighter, but some authors feel that they are dark
- the primaries are blackish and a bit shorter than in other plumages
- the wing tips do not reach the tip of the tail
TAIL
- on average, a little longer than in other plumages
- the feathers are white at the base with a dark terminal band that varies from more or less one half the tail length to as little as one-third of the length
LEGS
- the feathering extends to the toes and is generally quite light
- the feet are whitish according to some authors, and deep yellow according to other authorities
Subadult (second to fourth year) - Perched
The descriptions that follow pertain to the plumage stages between the juvenile and adult plumages. Differences may be subtle on perched birds and slightly easier to distinguish on flying birds because feathers and tail show better in flight.
HEAD
- feathers on rear of crown and nape light to vivid reddish brown and longer than in juvenile
- sides of head and throat dark brown but somewhat lighter than in juvenile
BODY
- generally dark and mottled with faded old feathers
- the undertail coverts are browner, but they still retain light basal areas
- the back is dark brown / black
WINGS
- the coverts are brownish and the primaries are black
- a tawny bar may be evident across the wing coverts
TAIL
- overall, the length is a little shorter than in juvenile plumage and more squarish terminally
- the amount of white basal area gradually reduces over the series of molts in this plumage
- a second narrow, dark band next to the terminal band develops after the juvenile plumage, and two narrow bands may develop as the molts of this plumage progress into more adult-like plumage. Male has two to three bands, female has two bands.
LEGS
- the feet are yellow with black talons
SIMILAR SPECIES
In North America, the Golden Eagle might only reasonably be confused with some immature plumages of the Bald Eagle. The first-year Bald Eagle resembles the adult Golden Eagle, but lacks the lighter, "gold" hackles and has a larger, mono-toned dark beak as opposed to a two-toned beak. It also lacks the tawny stripe across the wing. The Bald Eagle has bare tarsi whereas the Golden Eagle has feathered ones. Other transition plumages of the immature Bald Eagle has some degree of white on the back and belly which is lacking in the Golden Eagle of any age. In flight, the Golden Eagle has dark axillars in all plumages whereas the Bald Eagle has some degree of white axillars during all of the immature plumages. By the time the Bald Eagle axillars become dark, the white head and tail has been acquired. In any plumage, the immature Bald Eagle has distinct white patches only in the first three primaries. Thus, any eagle without a white head with dark axillars or wing linings, is a Golden Eagle. Any eagle with white markings on the wing linings is a Bald Eagle, irrespective of head color.
At some distance, vultures and condors might be mistaken for a Golden Eagle due to their size and overall dark coloration. Their habit of soaring with their wings in a pronounced dihedral and rocking back and forth in flight distinguish them from the Golden Eagle. The latter species does not hold its wings as high and has a steady flight. Perched vultures have reddish heads on adults and gray heads on immatures in contrast with the brown and gold head of the eagle. The Black Vulture has bold white wing patches at the tips of the wings - a trait not shared by any plumage of the Golden Eagle. The Black Vulture holds its wings flat when soaring, but it is a much smaller bird than the Golden Eagle and the wings appear short and wide. The fanned tail is also very short and wide. The California Condor is no longer likely to be seen, but is extremely large and flies in level flight with little flapping. Large triangular white patches in the axillar area distinguish this endangered species from any plumage of the Golden Eagle. The tail of the Golden Eagle is proportionately longer than that of a condor and the eagle is significantly smaller.
OTHER NAMES
The Golden Eagle is also referred to as "Black Eagle", "Brown Eagle", "Dark Eagle", "Calumet Eagle", "Mountain Eagle", "Canadian Eagle", "Royal Eagle", "Ring-tailed Eagle", "War Eagle", and "Black Mexican Eagle."
ETYMOLOGY
The genus name Aquila is Latin for "eagle." The species name chrysaetos is Greek for "golden eagle" which is obtained from the combination of khrysos for "golden" and aetos for "eagle." Golden refers to the color of the feathering on the nape. Eagle is a restricted reference to certain large, superficially similar diurnal birds of prey but it does not necessarily imply evolutionary or genetic relationships.
MYTHOLOGY
The Golden Eagle occupies a prominent place in the legends and culture of many peoples. From myths, legends, taboos, rituals, aesthetic appreciation, totems and heraldry, the belief in the sacred values of this bird extends deep into the culture of our native North Americans. Eagle feathers were used in ceremonies and worn by people to ward off evil spirits, or to empower themselves with the strength of the eagle itself. War bonnets were made by some tribes and symbolize the relationship embodied there.
VOICE
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.
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