Golden Eagle | Life Histories of North American Birds | A.C. Bent
Feather Pic Arthur Cleveland Bent

Life Histories of Familiar North American Birds
A chapter from the electronic book: Life Histories of Familiar North American Birds

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Golden Eagle
Aquila chrysaetos

[Published in 1937: Smithsonian Institution United States National Museum Bulletin 167 (Part 1): 293-315]

This magnificent eagle has long been named the King of Birds, and it well deserves the title. It is majestic in flight, regal in appearance, dignified in manner, and crowned with a shower of golden hackles about its royal head. When falconry flourished in Europe the golden eagle was flown only by kings. Its hunting is like that of the noble falcons, clean, spirited, and dashing. It is a far nobler bird in every way than the bald eagle and might well have been chosen as our national emblem. But then the golden eagle is not a strictly American bird, as the bald eagle is.

The golden eagle, as a species, is widely distributed throughout the Northern Hemisphere; seven races have been described from various regions of Europe and Asia besides our North American form, which is a large, dark race. Our race was once more widely distributed than it is now. At the present time it is very rare as a breeding bird anywhere east of the Rocky Mountains. I have two birds in my collection that were taken from a nest on Waldens Ridge, in the Cumberland Mountains, Tenn., in 1902; they were raised in captivity for over a year before they died and were given to me. At the present time these eagles are probably more abundant in the wilder portions of southern California than anywhere else in the country, but even there they have decreased decidedly within the past few years. Their decrease is mainly due to the indiscriminate use of poisoned baits and to shooting and trapping by cowboys, ranchers, and hunters, with the erroneous notion that they do more harm than good. With the decrease in the number of eagles we may look for an increase in the number of ground squirrels.

Courtship.--The courtship of the golden eagle is much like that of the Buteos, to which it is closely related. It consists mainly of spectacular flight maneuvers, spiral sailings in ever-rising circles, in which the birds frequently come close together and then drift apart; as they pass they almost touch. Occasionally one will start a series of nose dives on half-closed wings, swooping up again between dives and giving vent to his joy in musical cries. This form of nuptial play is indulged in by both sexes and is kept up, more or less, all through the nesting season. Perhaps it is only a form of joyful exercise. The birds are apparently mated for life, and if one is killed the survivor immediately seeks a new mate.

Nesting.--My personal experience with golden eagles' nests is limited to seven nests found in Arizona and five in southern California, from all of which I collected only one egg. The Arizona nests were shown to me by my late lamented friend, Frank C. Willard, who, after many years of experience with them, knew where to find several pairs of these fine birds. Our first nest was a disappointment, as we found it occupied by a pair of western redtails. We had driven over the divide in the Mule Mountains, from Bisbee, to visit this long-established nest, which was located near the top of a high, rocky cliff, rising abruptly from a valley; but when we reached the top of the cliff, we saw the hawk fly off the nest.

The following day, April 5, 1922, we visited two nests near Tombstone. One was on a small ledge on the face of a bulging, rocky cliff on the steep side of a mountain; it was about 75 feet from the bottom of the cliff and 25 feet from the top, having a fine outlook over the valley far below. This was also occupied by redtails, but, as it was a fairly easy climb with the aid of ropes, I went down to it and secured the two hawk's eggs. It was a huge nest of large sticks, roots, and stems of yuccas and was lined with strips of yucca and other soft fibers.

The other pair of eagles had two nests, which they used in alternate years. One was in an easily accessible place on a low pinnacle of rock, but it was not in use. The alternate nest was on the farther side of a steep little mountain, which we reached by climbing up a steep slope to the rocky summit; here the ridge dropped off suddenly in rocky cliffs and steep slopes. At the brink of the cliff we could see no nest, but by rolling rocks over the edge we started the old eagle off her nest only about 12 feet below us. It was a difficult nest to reach from above on account of the overhanging cliff, but I found a place where I could climb to a ledge below it and come up to the nest on the ropes. It was located on an outlying spur of a high rocky cliff, about 125 feet up from the base. It was a large, old nest, 4 by 5 feet in diameter, made of large sticks, stems, and roots of yucca and other coarse materials; it was lined with grasses, weeds, strips of inner bark, and other soft fiber. Its contents were rather interesting, a small downy young, only a few days old, a very rotten egg, which burst in my hand, and the remains, mostly the hindquarters, of 12 rabbits. The eagle had flown off in silence and did not show herself again, even while I was sitting in the nest and admiring the view.

Two other nests were found in the Dragoon Mountains, one in the Huachucas and one in the Catalinas. All were similarly located in commanding positions on rocky cliffs, where the birds could look out over a wide expanse of open country. We found no tree nests in Arizona, where big trees are scarce, except in the canyons.

In southern California it was different. Here, in 1929, with the aid of Wright M. Pierce and E. L. Sumner, Jr., I saw five nests in a variety of situations, two in trees and three on cliffs. The cliff nests were very similar to those found in Arizona and similarly located on rocky cliffs in low mountain ranges or on rough, steep, rocky hills. To reach the nest from which I secured my only egg, we had a long, tough climb up to the head of a winding canyon among some rough, rocky hills on the Mojave Desert. Here we saw the nest on a high cliff above a steep, rocky slope; it was only about 20 feet up from the base of the cliff and about 30 feet down from the top. The old eagle flew off when she saw us coming and circled way off in the distance. We climbed to the foot of the cliff and halfway up to the nest, but only with ropes let down from above could I negotiate the remaining few feet. The nest occupied the whole of a small shelf on a nearly perpendicular cliff. The nest measured about 4 feet in height and about 5 feet in width; it was a mass of large and small sticks, brush, and weeds and was profusely lined with dry and green sprigs of a stringy weed, which is very common here, and a few bits of down. It held one handsome egg on March 11.

In Los Angeles County on February 28 we flushed an eagle off a tree nest, where she probably had eggs; we did not climb to it, since Mr. Sumner was planning to make a study of the young later on, as he had done previously. The nest was 65 feet from the ground in the largest of a small group of sycamores in a hollow among low grassy hills. The eagle flew off when we were 100 yards away and did not return.

The other tree nest, from which the eagle had been seen to fly on two previous occasions, was visited on March 8. It was about 60 feet up in a big eucalyptus and well hidden in the thick foliage. The tree stood in an open field among the foothills of a rocky range in Los Angeles County. There were no eagles about, and the nest had apparently been robbed. A short distance away, in a small clump of eucalyptus trees, was another old nest, probably an alternate site.

Much has been published on the nesting habits of the golden eagle in California, as the eggs are handsome and high priced and consequently very popular among collectors; I have seen many large series in California collections. A large majority of the nests seem to be placed in trees, mainly in various oaks, sycamores, redwoods, and pines. The heights from the ground vary from 20, or even 10, feet in low oaks up to 75 or 96 feet in tall pines or redwoods. The nest is made of large sticks, some over 2 inches in diameter, finely interwoven, smaller sticks, twigs, brush, roots, grass, leaves, pieces of sacking, and other bulky rubbish; the lining is of softer materials, grasses, weeds, dead and green leaves, soft mosses, and lichen. Green grass, or green leaves, often attached to the twigs, are added from time to time, especially after the young are hatched. Milton S. Ray says in his notes: "The lining frequently varies with the particular pair of birds and also with the locality. A nest I found at a high altitude on a lofty and barren mountain side was merely lined with coarse roots. One in an oak-wooded canyon was lined with eucalyptus leaves, although no such trees were visible for miles around. Another nest was beautifully draped, hung, and lined with gray-green oak moss. So thickly was it covered with moss that it was very difficult to discern from a distance. Nests found in the humid coast belt in the great redwood forests were much more warmly lined; a typical nest was very thickly lined with rabbit fur, also some moss and eagle down." New nests are sometimes quite small, 2 1/2 to 3 feet in diameter and 18 inches high, but as they are added to from year to year they become quite bulky, 5 or 6 feet in diameter and 4 or 5 feet high.

In San Diego County a majority of the nests are on cliffs. While I was visiting James B. Dixon, at Escondido, he showed me a beautiful series of eggs that he had taken in that vicinity and pointed out some of the localities on rough, rocky mountains, where he had found the eagles nesting for many years. He (1911) says that each pair of birds has its own nesting and hunting range, from which others are driven out; but they have a peculiar habit of stealing materials from their neighbor's nest, which often results in a fight "over their stealings, diving and circling in the air and sometimes clashing together and falling thus several feet before breaking away from each other." He says further: "I have never yet found a nest that did not have some dagger leaves in it, and in some places the birds must have carried them for some distance. In other instances, pepper and eucalyptus leaves were used profusely in lining and were carried several miles as there were neither of these trees growing close by. The odor from either of these leaves is distasteful to bugs and lice of all kinds, and I think this the reason they took such pains to secure it when there was plenty of other nesting material close by."

Wilson C. Hanna (1930) has made some interesting observations on nest building activities, which begin in January in southern California. He says of one bird:

This bird would work pretty fast at nest building, as the following record indicates: 4:16 p.m., bird observed going to nest with stick in beak; 4:17, left nest; 4:19, returned to nest; 4:19 1/2, left nest; 4:22, sailed by nest but did not go to it; 4:23, returned from the south with such a large piece of brush that it was hard to manage; 4:23 1/2, left nest; 4:24 1/2, returned to nest, descending from high above it; 4:26, left nest; 4:27, returned with stick; 4:29, left nest; 4:30, returned to nest from the north with stick; 4:31, left nest; 4:33, returned from the south over the nest and descended to it from the north; 4:37, left nest; 4:47, sailed over nest and then on out of sight in the distance.

Mr. Ray writes to me: "While engaged in nest building the eagles are seldom in evidence as they sail along close to the ground. On one occasion Rose Carolyn Ray noted a bird curving low over a hilltop and then beneath a huge oak, where, after rising straight up to a lofty bough, it placed the material it was carrying for the repair of the old nest which it later occupied. In leaving the tree the bird departed in the same unobtrusive manner in which it came."

If the first set of eggs is taken from an eagle's nest, the bird will often, but not always, lay a second set about a month later, sometimes in the same nest and sometimes in an alternate nest. The same nest may be used for many years in succession, but oftener the birds build two or more nests and use them alternately. Joseph R. Slevin (1929) has published an interesting history of seven California pairs, which illustrates the territorial habit. The sparrow hawk and the western kingbird have both been known to nest in the lower parts of golden eagles' nests.

Some of the older cliff nests are very large, as they last for many years in a secure and sheltered position, until the lower parts are quite thoroughly rotted. Bendire (1892) mentions one that was 7 feet high and 6 feet wide. F. C. Willard (1916a) tells of one that was "six feet one way by eight the other. Dried cactus leaves comprised most of it, but there were some sticks in the base of it." He writes further: "On one occasion I was interested in watching one collecting sticks for its nest. It would alight in the top of a half dead juniper tree, walk clumsily out on a dead branch and break off a stick with its beak. It carried this stick in its beak as far as I could see it, passing close by me enroute to its nest. I watched it make several trips, using a powerful glass to assure myself that it really carried the sticks in its beak and not in its talons. A short time thereafter I watched another eagle carrying dried 'nigger-head' leaves in its talons. It was using them as lining."

E. S. Cameron (1905) described and studied an eagle's nest in Montana that "was situated near the top of a scoriaceous rock in the badlands, a crimson pillar which crowned a high butte sloping abruptly to deep washouts. The upper part of this column consisted of easily detachable pink layers, called laterite by geologists, but scoriae of every color strewed the base which rested on red ochre clay reminiscent of a painter's palette. Placed in a hollow niche of the wall face the eyrie was entirely enclosed and sheltered on three sides by a dome of rock. On the fourth, and open side, the enormous sunken nest greatly overlapped the seemingly inadequate ledge, which served as a support, and thereby secured the safety of the eggs and young."

A totally different Montana nest was in a tall pine about halfway up a steep hillside. He (1908b) says:

The eyrie, which consists of an immense pile of sticks, rests upon, and is built around, a number of green boughs, while a dead projecting branch near the center forms a convenient perch for the parent eagles. As would naturally be expected in the present case, the vertical height of the nest greatly exceeds the diameter, and its width is much inferior to the nest upon the rock previously described. Nevertheless, as seen from below, it conveys an impression of strength, which is not belied when it is reached, for a six foot man can sit in it with ease. On May 11, the whole external circumference of the nest rim was interwoven with an ornamental binding of green pine tops.

Roderick MacFarlane (1908) found this eagle breeding nearly up to the Arctic coast; he writes: "From various points along the valley of the Anderson River to its outlet in Liverpool Bay, and from near the mouth of the Wilmot Horton River in Franklin Bay, an aggregate of twelve nests of the golden eagle was procured in course of the breeding seasons from 1861 to 1865, inclusive. Ten of them were constructed on the side face, and within twenty or thirty feet of the summit, of steep and difficult of access earth and shaley ravine banks; and in the other two instances the nests were built near the top of tall spruce pines."

Eggs.--The usual set of golden eagle's eggs is two; full sets of one are common, sets of three rather rare, and at least one set of four has been taken (Ray, 1928). Mr. Hanna (1930) writes: "Nests with complete sets of eggs that I have personally examined in southern California have had only one egg in 35 percent of the cases, two eggs in 60 percent and three eggs in 5 percent." The shape varies from short-ovate to oval, or rarely to elliptical-oval; the shell is thick and from finely to coarsely granulated. The ground color varies from dull white to "cream-buff" or pinkish white. The variations in types and colors of markings are endless, but series of eggs from the same female usually run true to type. They are generally more or less evenly marked with small blotches, spots, or fine dots, but often the markings are unevenly distributed or concentrated at one end, and some are evenly sprinkled with minute dots. The eggs are often sparingly or faintly marked, or even nearly or quite immaculate. The usual colors of the markings are "bay," "amber-brown," "hazel," "tawny," "Mikado brown," "clay color," "vinaceous fawn color," and various shades of "ecru-drab" or "Quaker drab." Some very  pretty eggs have large blotches or washes of the drabs overlaid with browns.

The measurements of 59 eggs in the United States National Museum average 74.5 by 58 millimeters; the eggs showing the four extremes measure 85.7 by 64.3, 67.5 by 53, and 70.7 by 49.4 millimeters. An egg in the collection of C. S. Sharp measures 89 by 66.6 millimeters, the largest egg of which I have any record.

Young.--The period of incubation of the golden eagle has been variously reported as from 28 to 35 days; the latter figure seems to be based on the most accurate observation and is probably the most nearly correct. Most observers agree that the male does not assist the female in incubation, but he feeds his mate on the nest and helps to care for the young by bringing in food, which his mate feeds to the young, and by brooding the young occasionally himself. The incubating bird is easily frightened from the nest, although on rare occasions she has been known to remain on the nest until the climber has been near enough to touch her. She usually flies away in silence and disappears entirely, or remains at a distance. Only once have I ever seen an eagle return to her young while we were watching at a long distance, and then only for a few seconds. I can find no authentic record of an eagle attacking an intruder at her nest. If disturbed during the early stages of incubation, she may desert the eggs but never the young, although she seems quite indifferent to their welfare. Mr. Ray says in his notes: "Many birds resent any interference with their nests and will frequently desert them whether they are in the course of construction, completed, or even containing partial or full sets of eggs. In some cases they have apparently shown their extreme disfavor by casting the eggs out of the nest; while I have never actually seen eagles engaged in taking such drastic measures, on a number of occasions I have found eggs on the ground just below the nests where an almost inaccessible situation made it difficult to see how they could have been disturbed by any outside agency."

Several British ornithologists have, at the cost of much effort, personal discomfort, and risk, spent considerable time studying and photographing the home life of the golden eagle. I would recommend reading the published reports of H. B. Macpherson (1911), H. A. Gilbert and Arthur Brook (1925), Duncan MacDonald (1926), and Seton Gordon (1927). Much of what follows is taken from their writings and from the observations of E. S. Cameron (1905 and 1908b) in Montana. I regret that space will not permit more elaborate quotations from these interesting accounts.

E. L. Sumner, Jr., has sent some very full notes on the growth of a brood of young eagles in California, which he measured and weighed once a week from the time they hatched until they left the nest. The loss in weight of the eggs prior to hatching is interesting; on February 27 the three eggs weighed 143, 143.4 and 133.7 grams; on March 20 the first egg had just hatched, and the other two eggs had shrunk in weight to128.6 and 126.2 grams. The newly hatched chick weighed 105 grams. A week later all three had hatched, and the chicks weighed 357.3, 232.3, and 98.2 grams, showing that they probably hatched at intervals of two or three days. On April 3 the youngest and smallest chick had disappeared and the other two had increased to 1,022.7 and 584.7, the older chick being then two weeks old, and ten times as heavy as when hatched. From that time on both birds increased steadily in weight, along slightly divergent lines; on May 8, when seven weeks old, they weighed 3,851.7 and 2,801.7 grams. During the next week, they both dropped off over 400 grams in weight, but regained this and more during the following week, so that on May 22, when nine weeks old, they weighed 4,061.7 and 2,981.7. This, compared with 4,169.4, the weight of an adult male, emphasizes the lightness of the smaller bird, probably a male. This was the last weighing, as the birds left the nest during the following week.

Mr. Sumner noted that when first hatched the chick was unable to distinguish objects but could chirp incessantly. At the end of a week it could see well, move its head about, and bite at things. When two weeks old it could crawl and soon learned to rear up; but even when seven weeks old it could barely maintain its balance when placed on a limb.

Mr. Sumner's eaglets left the nest when between 9 and 10 weeks old; this was a tree nest and the eaglets had been often disturbed. Mr. Gordon gives the time in one case (1915) as 9 weeks and in another case (1927) as 11 weeks, saying: "The eyrie takes at least six weeks in the building or the repairing, and the eagles continue to bring fresh fir branches and bunches of heather to the eyrie until the last fortnight before the nest is vacated--that is, until the eaglets are about nine weeks old."

The eaglet that Mr. Macpherson (1911) watched on a cliff nest began leaving the nest and wandering about on the ledge when a little over nine weeks old, but did not fly from the eyrie until about two weeks later. He noted that the young eaglet, while still in the downy stage, "was fed with great regularity twice a day--at daybreak and about 5 p.m." The food, mainly grouse and hares, is brought to the nest by both parents, but principally by the male. The game, at this age of the young, is stripped of fur or feathers and usually disemboweled before it is brought to the nest. The female does practically all the feeding, swallowing the intestines herself and picking out tidbits from the liver or other dainty morsels to feed to the young. All uneaten portions of the food are carried away. Later on, when the plumage is growing and the young eaglet is strong enough to tear up its own food, the game is left entire, he is taught to feed himself, and the remnants of the food are not so carefully removed. As the time draws near for him to leave the nest he is encouraged to exercise his legs and wings by placing the food beyond his reach on the ledge.

Of the eaglet's behavior Mr. Macpherson (1911) writes:

After his feast the Eaglet walked round the edge of the nest and began to play. He behaved exactly like a child thrown upon its own resources for amusement and compelled to fall back upon any handy article as a toy. Small pieces of heather in this case served his purpose, and he appeared to enjoy lifting them from the ground and throwing them down again. He also picked pieces of moss from the rocks and only desisted from this occupation after having completely stripped the walls of the eyrie. . . . He next began to make his toilet, carefully removing all the loose down, which was now freely coming away. This was accomplished with the aid of his beak, and, the task completed to his satisfaction, he lay down and went to sleep.

It often happens that one of a pair of eagle's eggs proves to be infertile. But oftener one of the eaglets disappears; the smaller and weaker bird may not be able to secure his share of the food and thus may weaken and die from exposure. The larger one, usually the female, often attacks and may kill her little brother. Seton Gordon (1927) twice witnessed spirited fights, of one of which he writes:

Twenty minutes after the parent had left the family, Cain commenced a very determined and entirely unprovoked attack upon her brother. She tore from his unfortunate person great billfuls of white down and even tiny feathers. Abel in desperation ran to the far side of the eyrie and lay there, quite still and very sullen. Cain thereupon stood up, flapped her downy wings, and uttered several wild and piercing yells of victory. There was an extraordinary and quite unearthly quality in these calls which deeply impressed itself upon my mind. Great billfuls of her brother's down adhered to her bill, and she had much trouble in ridding herself of the fruits of her easily gained victory.

Mr. Cameron (1905) says of the food of the young in Montana that "the nest always contained either sharp-tailed grouse, jack-rabbits, cotton-tails, mountain rats, meadowlarks or snakes," but no carrion. He says that the eagles catch a number of rattlesnakes. "According to eye-witnesses they feint several times at the snake to make it uncoil and seize it just behind the head with one foot, while gripping it further back with the other. The snake is then taken to a tree or rock and the head torn off, which according to one observer is immediately devoured, before the body is deposited in the eyrie."

Mr. Sumner, in California, found numerous ground squirrels and the remains of a cottontail, a crow, a meadowlark, and a gopher snake in the nest.

Young eagles remain in the vicinity of their nest for a long time after they leave it. They are probably at least three months old before they gain the full power of flight. They are partially fed by their parents at first and are watched and guarded by them until they learn to hunt for themselves, probably until early fall. Dr. Loye Miller (1918) published the following account, as given to him by one of his students:

Last summer while my father and I were extracting honey at the apiary about a mile southeast of Thacher School, Ojai, California, we noticed a golden eagle teaching its young one to fly. It was about ten o'clock. The mother started from the nest in the crags, and roughly handling the young one, she allowed him to drop, I should say, about ninety feet, then she would swoop down under him, wings spread, and he would alight on her back. She would soar to the top of the range with him and repeat the process. One time she waited perhaps fifteen minutes between flights. I should say the farthest she let him fall was 150 feet.

My father and I watched this, spellbound, for over an hour. I do not know whether the young one gained confidence by this method or not. A few days later father and I rode to the cliff and out on Overhanging Rock. The eagle's nest was empty. (Miss F.E. Shuman)

Plumages.--During the nest life of the eaglet, the plumages may be roughly divided into three stages--four weeks in a pure downy stage, four weeks during which the plumage is growing, and three weeks in a nearly feathered stage. When first hatched it is completely and thickly covered, except on the toes and back of the tarsus, with short, thick, dirty-white or yellowish-white down, overlaid on the upper parts with a scanty growth of long, grayish-tipped, hairlike down. This is replaced later by a longer, thicker, woollier, pure-white down. At an age of four weeks the wing quills are sprouting and beginning to burst their sheaths. During the next week the tail quills appear. At the end of eight weeks Mr. Sumner's larger bird had a wing spread of 62 inches, primaries 11 inches long, and tail quills 7 inches. Meantime the body plumage has been growing, beginning with the scapular and back plumage during the fifth week; this is soon followed by the wing coverts and then the feathers on the sides of the breast. By the end of the seventh week the upper parts are fully feathered and the under parts largely so, but the head and neck are still downy and there is much down on the breast, flanks, and legs. At 10 weeks the juvenal plumage is practically complete, and the eaglet is ready to fly.

In fresh juvenal plumage the young eagle is considerably darker than the adult; the crown and hackles are darker and duller, not so golden; the upper parts vary from "blackish brown," or nearly black, to "clove brown," with a purplish sheen; the under parts are only a shade browner, with a purplish bloom on the breast; the basal third of the back feathers and the basal half of the breast feathers are pure white; a narrow white tip on the tail soon wears away, leaving a broad terminal band of brownish black, covering about one-quarter of the central rectrices and graduated up to one-half of the outer feathers; the rest of the tail is white, washed with gray on the outer webs and more or less spotted with black above the dark band; the remiges are black, with considerable white near the bases of the inner primaries and all the secondaries; the tarsi are dull white.

The juvenal plumage is worn for one year without change except by wear and fading. From that time on progressive changes take place through annual complete molts, toward maturity. The molts are mainly accomplished between April and July but may extend from March to October. The fully adult plumage is not complete until the bird is four years old or more. Meantime the white in the wings gradually disappears; the basal white in the body feathers grows less until there is little or none in the adult; the white in the tail decreases at each molt, becoming purer white, until the adult tail shows no white, but is more or less indistinctly and irregularly barred or spotted with very dark gray or brown; the feathers of the upper breast and the tibiae are edged with "ochraceous-tawny" or "tawny-olive" and the tarsi are pale brown or "tawny-olive."

Food.--The golden eagle is such a large and powerful bird that it can attack and kill many large mammals and birds, and it shows great courage in attacking animals larger than itself, many of which are capable of inflicting severe injury on the brave bird. The list of mammals recorded includes deer and their fawns, antelopes, lambs of mountain sheep, goats and their kids, domestic calves, lambs, dogs, cats, young pigs, foxes, hares, rabbits, ground and arboreal squirrels, raccoons, prairie dogs, woodchucks, marmots, spermophiles, porcupines, opossums, skunks, weasels, martens, pocket gophers, rats, mice, and moles. The list of birds is not so long, but includes great blue heron, turkeys, geese, ducks, goshawk, red-tailed hawk and short-eared owl (both twice recorded), sage-hen and other grouse, ptarmigan, quails, band-tailed pigeon, crow, domestic poultry, curlews, plovers, kingfisher, meadowlarks, and thrushes. Birds, particularly the smaller species, are taken mainly during the nesting season as tender food for the young. But at all seasons mammals seem to be preferred. Eagles kill many snakes and an occasional tortoise; they often feed on carrion when live game is scarce.

The stomach contents of 30 golden eagles reported by Howard Kay Gloyd (1925) show their preference for mammals during the fall and winter months; 11 had eaten cottontail rabbits, 7 had taken jack rabbits, 9 prairie dogs, and 1 each had eaten a woodchuck, a ground squirrel, a short-eared owl, an opossum, a fox squirrel, and a red-tailed hawk.

There are numerous, apparently authentic, reports of these eagles killing large animals. F. C. Willard (1916b) reports the killing of a four-point white-tailed deer in Arizona.

The deer had been pounced upon by one or more eagles as it floundered in the deep snow, and its back was fearfully lacerated by the talons. After it had succumbed, the carcass was dragged downhill over one hundred yards until it lodged against a large boulder. Three eagles were feeding on in when first discovered by some prospectors. . . .

Recently two cowboys in the employ of Mr. Lutley came upon three eagles feeding upon the body of a calf about seven months old. . . . the back of this calf gave every evidence that it had been killed by the eagles.

C. F. Morrison (1889) reports that a golden eagle in Montana "had captured and killed a good sized Black-tail Deer, and was shot while sitting on its body." Mrs. Seton Gordon (1927), while watching a nest, saw "a wonderful sight. The cock eagle alighted, exhausted, at the eyrie with a roe-deer calf held in one great foot! The powerful bird arrived from below, and was only just able to raise himself to the nest with his large burden." A few days later there "were two more roe calves and the skeleton of the first" in the nest. Aiken and Warren (1914) write:

The Golden Eagle is reported to be one of the worst enemies of the mountain sheep, killing many of their lambs. A Mr. Waldron told Aiken that many years ago when driving on the plains with several others he saw an eagle of this species attack and kill an antelope. The bird pursued a bunch of the animals, singling out one, and when close enough struck it on the back with its talons, and while clinging there and tearing with claws and beak it at the same time beat its prey's sides with its wings. The men drove close enough to shoot the eagle, and found the antelope to be dead with its back badly torn by the bird. Aiken was also told that an eagle was seen to pounce upon a two-year-old calf near Hartsel but was driven way before any harm was done. Rather large prey for the bird to tackle.

M. P. Skinner's notes give a somewhat different impression, for he says: "I have made particular inquiries whether these eagles have ever been seen to kill mountain sheep lambs, but not one of our rangers has ever done so. In carrying on my inquiries outside the Park, I heard from one correspondent, previously unknown to me, that he had seen an attack wherein two golden eagles seemed to try to knock the lamb off its cliff, or at least to scare it so that it would fall. This inquiry extended to many parts of the United States and to some localities in Canada."

Mr. Cameron (1908b) states that R. L. Anderson came upon "three Golden Eagles which were devouring an adult buck antelope" in mid-winter in Montana. He continues:

Despite the bitterly cold weather, the antelope was warm and limber when found, as it had only been quite recently killed. The eagles had torn a large hole in its back with their terrible talons and were feeding on the kidneys and entrails. Mr. Anderson at once investigated the scene of the struggle and could easily read the gruesome details on the deep, crusted snow. The eagles had obviously stampeded a bunch of antelope, and then cut out a victim by a combined attack. Leaving the herd, the latter endeavored to escape down a small right hand draw, but after covering about a hundred yards was beaten back by the eagles. It then crossed a ridge on which the main antelope trail ran at right angles to its own and, hard pressed by its assailants, struggled down a narrow left hand draw to the place where it succumbed. Altogether the antelope could barely have covered three hundred yards after the first attack by the eagles. The victim, which had evidently offered a gallant resistance, seems to have made a stand in three places, chiefly where found, but also at points along the trail. The crimson stained snow and thickly strewn hair, added to the well defined wing prints of the flapping and dragging eagles, sufficiently revealed this prairie tragedy. One or more of the birds must have clung tenaciously to their quarry's back and from the deep wounds thus inflicted "the blood had spurted out as when a cow's horns are sawn off."

He also has much to say about the destruction of prairie dogs by these eagles. One of his pairs that lived near prairie-dog towns always had one or two of these animals in their nest. He says:

Now the destruction of prairie dogs is of the greatest benefit to the settlers, as in this locality (Knowlton) they have increased to an alarming extent. On some ranches the rodents play havoc with the crops and "dog towns" have encroached upon miles of good grazing land, reducing it to a desert. It is only necessary to read the forcible paper on "The Prairie Dog of the Great Plains" by Dr. C. Hart Merriam, quickly to realize what an unmitigated pest this animal becomes, and how rapidly its towns spread. As quoted therein, Professor W. W. Cooke computes that "32 prairie dogs consume as much grass as one sheep, and 256 prairie dogs as much as one cow."

Throughout the month of April, and for two days in May, allowing an average of three prairie dogs per diem, we get a total of 96 prairie dogs up to the time the eaglets are hatched. Subsequently, until the young birds forage for themselves (about Aug. 1), if we allow only six of the rodents a day, the total is obtained of 540 prairie dogs for seventy-four days sustenance of four eagles. Thus we have a grand total of 636 prairie dogs during four months for one pair of eagles, which is probably well within the mark. An eagle intent on capturing a prairie dog floats down leisurely above the "town" at a medium height on motionless wings. Preliminary inspection of the hunting ground is accomplished in wide circles or long sweeps, perhaps two or three miles each way, so as not to unduly alarm the game. Passing over at long intervals, the bird scans the dog town and judges of the prospect for a successful stoop. The "dogs" are of course immediately on the alert, but can only see their enemy for a short time on account of the high surrounding pine hills, and, indeed, most "dog towns" are too extensive for the denizens at one end to notice an eagle passing over at the other. Moreover, an unsuccessful eagle will keep on the wing for several hours, and it is almost certain that the hungry prairie dogs will relax their vigilance at last. When the eagle considers that a favorable chance has arrived it sinks lower, so as to bring the distance between itself and the animals to something like 75 or 100 yards. Should the latter still remain above ground, the royal bird suddenly folds its wings, and, with meteoric rush, falls head first towards the astounded prairie dogs. These scamper for their holes, but about three yards from the ground the eagle spreads its wings and, swiftly following the intended victim, darts out a cruel foot to grasp it. If the attack fails, as sometimes happens, the eagle mounts in a slow, reluctant manner which plainly reveals its disappointment.

This bold bird sometimes "catches a Tartar." Albert Lano (1922) had one brought to him that had attacked a porcupine; "it was literally covered underneath with quills. In fact there were a number of quills in the roof of its mouth. The body was much emaciated and many of the quills had penetrated deep into the flesh causing pus to form."

These eagles have often been known to attack foxes caught in traps, but the following spirited encounter, described by Mr. Gordon (1915) is unique:

The eagle was devouring the carcass of a blue hare when a fox sprang from the surrounding heather and seized the great bird by the wing. A well-contested struggle ensued in which the eagle made a desperate attempt to defend itself with its claws and succeeded in extricating itself from its enemy's grasp, but before it had time to escape Reynard seized it by the breast and seemed more determined than ever. The eagle made another attempt to overpower its antagonist by striking with its wings, but that would not compel the aggressor to quit its hold. At last the eagle succeeded in raising the fox from the ground, and for a few minutes Reynard was suspended by his own jaws between heaven and earth. Although now placed in an unfavorable position for fighting his courage did not forsake him, as he firmly kept his hold and seemed to make several attempts to bring the eagle down, but he soon found the strong wings of the eagle were capable of raising him, and that there was no way of escape unless the bird should alight somewhere. The eagle made a straight ascent and rose to a considerable height in the air.

After struggling for a time Reynard was obliged to quit his grasp, and descended much quicker than he had gone up. He was dashed to the earth, where he lay struggling in the agonies of death. The eagle made his escape, but appeared weak from exhaustion and loss of blood.

Hares, rabbits, and other smaller mammals are usually caught by chasing them in the open and pouncing on them, but Mr. Willard (1916a) witnessed another method: "In company with some friends one day, I watched a pair of these eagles hunting jack rabbits. They swooped down and drove the rabbit to cover under a mesquite bush. Then one alighted close by and began to walk toward the rabbit. He was so frightened he dashed from his shelter only to be snatched up by the other eagle which had been hovering close overhead."

Grouse, ptarmigan, and quail are also captured by swift pursuit in the air, as eagles are among the swiftest of fliers. Dr. A. K. Fisher (1893) quotes the following account by Robert Ridgway:

We were standing a few yards in the rear of a tent when our attention was arrested by a rushing noise, and upon looking up the slope of the mountain we saw flying down the wooded side with the rapidity of an arrow a Sage Hen pursued by two Eagles. The Hen was about 20 yards in advance of her pursuers, exerting herself to the utmost to escape; her wings, from their rapid motion, being scarcely visible. The Eagles in hot pursuit (the larger of the two leading), followed every undulation of the fugitive's course, steadily lessening the distance between them and the object of their pursuit; their wings not moving, except when a slight inclination was necessary to enable them to follow a curve in the course of the fugitive. So intent were they in the chase that they passed within 20 yards of us. They had scarcely gone by, however, when the Sage Hen, wearied by her continued exertion, and hoping, probably, to conceal herself among the bushes, dropped to the ground; but no sooner had she touched it than she was immediately snatched up by the foremost of her relentless pursuers, who, not stopping in its flight, bore the prize rapidly toward the rocky summits of the higher peaks, accompanied by its mate.

It can be seen from the foregoing quotations that the golden eagle is a very dangerous bird, a powerful influence for either good or evil according to the conditions in its habitat. Its natural and favorite food during most of the year consists of a long list of injurious rodents, which are prolific breeders. Where the eagles can keep these rodents in check, they are of great benefit to agriculture. But where they do much damage to domestic animals, the eagles may have to be controlled. Eagles kill some fawns and a great many grouse, but let us remember that all these wild creatures have existed for untold ages in apparent balance. Probably the eagle's victims include more of the weak and sickly individuals than of the strong and healthy ones, which greatly improves the strain and produces a healthier and more vigorous race by the survival of the fittest. We once found under a golden eagle's nest in California the dried remains of a wildcat.

Behavior.--The flight of the golden eagle is the embodiment of grace and power. To my mind it is more impressive than that of the bald eagle. The bald eagle is said to be swifter on the wing, but I doubt it. It is certainly inspiring to watch the spirited dash of this great bird in pursuit of its running or flying quarry. There are few swifter runners than the jack rabbit and few swifter flyers than the band-tailed pigeon, but this eagle is more than a match for either in an open chase. Mr. Gordon (1927) thinks "that the downward rush of the golden eagle is the swiftest thing, as it is the most magnificent thing, in the bird world." Its lofty soaring flight is equally grand, as it mounts in ascending spirals up into the clouds until lost to sight. Mr. Gordon (1915) again writes:

Then one day the north wind crossed the sea, and arrived at the eagle's home. And the eagle felt the cool arctic breeze and sailed out from his giant rocks which by now were burning hot in the fierce rays of the sun. With his pinions wide outstretched he leaned on the refreshing wind, which bore him strongly upward, without a single stroke of his wings to help him on his way. So he mounted higher and higher till he had risen far above his native hill-top, and was outlined, a mere speck, against the dark blue of the sky. Still upwards he sailed, and for some time longer the watching stalker kept him in view, in the field of his glass. But at length he reached a point at which he was invisible, even by the aid of a telescope. From that point what a gorgeous panorama must have been laid out before his sight in the light of the summer sun. Even the highest tops were now far far below him, and the river in its windings down the great glen must have appeared as a thin silvery streak.

Lila M. Lofberg (1935) writes of her observations while watching a pair of golden eagles near their nesting site at Florence Lake, Calif.:

The most interesting thing that has occurred while I watched has been their aerial circus. Whether this occurs more than once a year I cannot say, but I have never seen it more than on one day during the season. A distant call first attracts my attention. This comes from a mere dot in the sky. The second bird then leaves its perch on the nesting ledge and soars in wide circles, upward. Before it can attain the height of its mate, the "dot" comes hurtling down with closed wings, at terrific speed. When not over a hundred feet from the ground and just as I am sure it will be dashed to pieces, out come the wings and this bird instantly goes into a series of daredevil stunts. It rolls, stands on its head or tail, or slides earthward sidewise, with extended wings. Between these it may perform flights that remind me of a skater cutting figures on the ice. When it has exhausted its repertoire it ends on a line with the nest. But instead of flying straight to it, the eagle makes three perfect loops in the air, coming out of the last within a couple of flaps (of the wings) of the ledge.

Meanwhile the one in the air has been forgotten entirely but soon the faint call reminds me to look upward to find that it, too, has become a dot. Upward starts the resting eagle. Down comes the distant one to go through the same routine. Always these flights end with those three loops that bring them onto the nesting ledge. For an hour or more they continue this exciting sport. Then the one on the ledge fails to heed the call and remains until the other has alighted beside it. Then off they fly together toward Blaney Meadow, about five miles to the southeast of their home.

William Brewster (1925) witnessed a thrilling swoop of a golden eagle at a great blue heron:

Drifting, presently, over the place where the Heron had settled and evidently noticing the big bird for the first time, the Eagle checked his flight in the middle of a half-completed circle to poise for an instant on rapidly-vibrating wings, precisely as a Kingfisher will hover over a school of minnows. Then he swooped, apparently as straight and vertically as a heavy stone may fall, yet all the time revolving like a spinning rifle bullet, if more slowly, thereby showing us his (normally) upper and under parts alternately and making no less than four or five such turns before passing out of sight. Never before have I seen anything of the kind that seemed nearly so wonderful and impressive. As the great bird plunged headlong, from a height of at least one hundred yards, his wings, apparently set and almost closed, made a sound like that of a strong wind blowing through pine branches. His momentum must have been tremendous as he neared the earth. How it was finally checked and what else transpired behind the line of fallen trees I am, of course, unable to report. Without doubt the Eagle stooped at the Heron and quite as certainly failed to strike it down; for after an outburst of loud and prolonged squawking it rose above the trees and flew off at its very best pace, evidently badly frightened. Perhaps the Eagle had merely been amusing himself by bullying it, a diversion to which all strong-winged birds of prey are more or less inclined.

At another time he saw a young eagle attacked by an osprey, of which he writes:

After making the fruitless attempt to capture a Duck, he was assailed by an Osprey who kept darting down and striking at him from above, precisely as a Kingbird attacks Crows and other large birds. Every time the Osprey came within six or eight feet of him the Eagle would turn back downward and thrust up both feet with their talons extended, as if hoping to clutch his tormentor. This action was repeated at least half a dozen times, and performed so quickly that it was difficult to follow with the eye, although for a fraction of a second the upstretched legs and widespread talons showed distinctly enough against the sky.

Mr. Sumner has seen a young eagle pursued by a flock of avocets and driven away, one attacked by a blackbird, and one, which was standing on the ground, was attacked by a red-tailed hawk; the hawk--

which had been circling in the air, dove at him three times from a height of 300 to 400 feet. Each time the redtail dove the eagle jumped up from the ground and flung himself, while in the air, upside down so as to oppose his talons to those of the hawk. By and by the hawk stopped diving and began to circle again, the eagle staying where he was, but when the eagle got up and flew farther into the hawk's territory--flying leisurely--the redtail, although quarter of a mile or so from him, flapped his wings faster than I have ever seen a redtail flap, and was overhead in less than 30 seconds--like an airplane overtaking a freight train--and dove at him as before.

Mr. Skinner tells me these "eagles are much harassed by the ravens and crows"; he has often seen one "on the ground surrounded by a circle of ravens waiting for it to fly and the sport of mobbing to begin."

The prevailing belief that an eagle will attack anyone attempting to rob its nest is entirely erroneous. I can find no record of anyone being struck by an eagle at its nest, and only on very rare occasions has one been bold enough to even threaten the intruder. Evidently parental affection does not show itself in bravery, but hunger often makes the eagle bold and even savage; also a wounded eagle will show fight and even make an aggressive attack. Dr. E. W. Nelson (1887) says: "On one occasion a pair was disturbed by a friend of mine while they were feeding upon the remains of a hog in northern Illinois. As my friend approached the birds arose and swooped fiercely at him. Both birds were shot almost at the muzzle of the gun; the first fell dead almost at his feet; but this apparently seemed only to increase the rage of the survivor, which renewed the attack until it, too, was disabled."

Mr. Cameron (1907) relates the following story as told to him by a shepherd:

He narrated how from some distance away he saw an eagle stoop at one of the dogs, and hang above it as raptorial birds are wont to do when attacking ground game. The dog, not paralyzed like a hare, at the proximity of the great bird, ran towards its master, when the hovering and expectant eagle fixed one foot on each side of the collie's throat and endeavored to bear aloft the shrieking animal. The shepherd described how during the few minutes that he was running toward the struggling pair and trying, incidentally, to find a stick, the eagle made frantic efforts to carry away the dog, which seemed unable, when clutched in this manner, to make any attempt to free itself. According to the story, the bird was flying all the time, in any case flapping its wings, and, although prevented from rising by the weight of the quarry, it was able to drag the helpless dog to and fro. The eagle had, in fact, too good a hold for her own safety and was ignominiously killed by blows on the head with a stick.

An index to the food resources of the golden eagle in the mountains of northern British Columbia was afforded by a nest examined by Edward A. Preble. He says:

The nest, built on a ledge overlooking the valley of the South Fork of Bear Creek, in the Babine Mountains, was found on August 3, 1913. It had just been vacated by the sole young bird that had been raised in it.

The nest was built in a vertical cleft or "chimney" in the cliff, and the site was plainly an old one, for the labors of successive years had reared a structure nearly 20 feet high. Access to the nest proper was somewhat of a problem, but by taking advantage of slight projections on the face of the cliff beside the nest I soon reached the top. Here was the usual depression, flattened out by the weeks of use by old and young. The chief interest, of course, centered in the remains left from the feasts that had contributed to the growth of the young eagle now about to begin its active life. I made no attempt to count the individuals represented by the remains, which, of course, included only those that chance had suffered to remain, but I was careful to identify all the species represented. Varying hares (Lepus americanus) and marmots formed the bulk. The latter were mainly the large hoary marmot (Marmota caligata), but one skull of the small relative of our eastern species (M. m. ocracea) was among the lot. Part of the skin and skeleton of a marten (Martes americana) proved somewhat of a surprise. These comprised the list of the mammals, the remains of smaller ones, if there had been any, not being in evidence. Among the birds whose relics had lodged in the structure was an adult goshawk, a genuine surprise, and a number of blue grouse (Dendragapus o. richardsoni). The cliffs on which the nest was placed held the homes of many bushy-tailed wood rats, and there were signs that they had occupied at one time the lower parts of the eagle's structure, but there was no evidence that any had been captured.

In my ascent of the nest I inadvertently disturbed a healthy colony of yellow jackets that had built their own home about halfway up the structure. Fortunately for the success of my deliberations aloft I was then unaware of this important circumstance; but, when nearly halfway down, I was met by an advance guard from the enraged colony. There was only one way out, and I made the remainder of the descent in record time, glad to escape with a moderate number of stings.

This episode over, I turned my attention to the young bird, which still occupied his perch on the verge of the broad ledge where I had first seen him. While I was at the nest he had uttered at intervals a querulous rattling call, evidently an appeal to his parents, one of which had been seen once or twice at a distance. At my approach he regarded me with a reserved indifference. He was evidently a male and fully grown, and his dark lustrous juvenal plumage was in perfect condition. Although I believe he had not yet flown, I concluded that he was able to take off. Under my judicious but firm encouragement he launched into the air, and after a few somewhat clumsy but effective attempts to master the art of balancing he soared and flapped off down the valley, finally perching awkwardly on the summit of a spruce nearly half a mile below. On our way out of the mountains about ten days later the eagles were still in the vicinity of the aerie.

There are many old tales of eagles carrying off young children, but most of them are pure fabrications by sensational reporters. An eagle, if pressed for food, might carry off a small baby that had been left in the open unprotected, but such an opportunity must occur very rarely. Stories of babies being found in eagles' nests, practically unharmed, are purely imaginary, as eagles are well known to kill their prey at once. Mr. Forbush (1927) has investigated a case, which seemed to him authentic; an eagle attacked a little girl, nine years old, and cut and bruised her arm quite badly before it was beaten off. It is doubtful if an eagle could lift anything heavier than a very small baby. Mr. Cameron (1905) says: "Personally I have never known an eagle to carry anything heavier than a seven pound jack-rabbit and would think eighteen pounds (the extreme weight of a jack-rabbit or a Scotch brown hare) to be the extent of the largest eagle's capacity. It follows, therefore, that the lambs taken are very small."

The weights of the fawns and the fox, referred to above, were not definitely known, but they probably did not exceed 18 pounds and may have weighed much less. An eagle in rising from level ground must use its feet to spring into the air; therefore, if one or both feet are needed to hold its prey, it is handicapped accordingly. From an easy take-off on a steep slope it could probably lift its own weight, 14 to16 pounds, or perhaps more.

Mr. Ray's notes contain the following interesting items:

In one instance while at a lofty nest, just as I was about the examine the set of two eggs it contained, the massive bird, entirely unaware of my presence, came sailing in and lit upon the ledge of the nest but a few feet away. It was, for me, an anxious moment. However, with a loud call and by waving my hat in the air, the badly frightened eagle immediately took flight.

On another occasion, while at an elevation of 7,500 feet in the high Sierras, I was crawling on the ground and just emerging from a dense thicket of buck brush after a fruitless search for a fox sparrow's nest, when I noticed a great shadow growing larger and larger on the ground at my feet. Now, as I stood up, I perceived just above my head a great golden eagle with pendant legs and outstretched claws. Quickly seizing a nearby stick and waving it above my head, I just narrowly missed striking the bird, which, apparently greatly surprised at my action, quickly sailed away. It was evident that the bird had mistaken me for some mammal as I emerged from the brush.

Voice.--The golden eagle is mainly a silent bird. It usually leaves its nest in silence and does not fly around and scream, as so many of the hawks often do. I have no record in my notes of ever having heard it. Bendire (1892) says: "The usual call note is a shrill kee',-kee',-kee', uttered in a high tone; it is often heard in the early spring before nidification commences. Another note not so frequently used--one of alarm--is kiah-kiah, repeated a number of times."

Dawson (1923) writes: "In case of invasion, the king of birds can only lurk anxiously in the offing and give vent to his anxieties by a peculiar screaking, known throughout literature as a 'scream,' cheop' cheop', tsyewk' tsyewk'--slowly. This is a rather pathetic and quite inadequate sound, if intimidation be intended. Indeed, on occasion, it sounds more like the meditations of a young 'broiler' than it does like a master cry."

Field marks.--The adult golden eagle is a large dark-colored bird, appearing almost black in certain lights, with no white showing anywhere. In favorable lights at short range the golden hackles on the nape may show, but one must be very near to see the feathered tarsi. In the immature bird the white base of the tail is conspicuous, and also the white spaces in the wing formed by the white bases of the secondaries and inner primaries.

When the bird is soaring it holds the broad wings horizontally and not at an upward angle, as does the turkey vulture. The wing beats of the golden eagle are quicker and more vigorous than those of the bald eagle.

Winter.--The golden eagle is practically resident all the year round throughout most of its range, though many of the more northern birds are forced to drift southward during severe winters and wander about in search of a food supply. Deep snows and periodic scarcity of game make it hard for them to get a living. Lucien M. Turner says in his notes that it is very rare in northern Labrador and Ungava at any season, but occasionally a specimen "may be seen during the moderate periods occurring in winter."  A. D. Henderson (1920) shot a golden eagle in northern Alberta in January 1907 and says: "The number of Eagles in the country that winter both Golden and Bald-headed, the Golden Eagle predominating, would hardly be believed unless actually witnessed. Every little muskeg had one or two and some four or five of the great birds perched on stubs or soaring overhead, all living on the rabbits which were present in thousands. Eagles and Ravens were a great nuisance to the trappers that winter, destroying many fine skins. The following winter you could walk many miles without crossing a rabbit track and the birds and animals of prey had departed."

Golden Eagle* Aquila chrysaetos

*Original Source: Bent, Arthur Cleveland. 1937. Smithsonian Institution United States National Museum Bulletin 167 (Part 1): 293-315. United States Government Printing Office