私たちは、何年もの間、日本のエンターテインメント ニュースを生き、呼吸してきた情熱的なエンターテインメント ニュース ジャンキーの小さなチームです。
golden eagle, /golden-eagle,
Video: The Golden Eagle – Master of the Sky | Free Documentary Nature
私たちは、何年もの間、日本のエンターテインメント ニュースを生き、呼吸してきた情熱的なエンターテインメント ニュース ジャンキーの小さなチームです。
golden eagle, 2021-03-12, The Golden Eagle – Master of the Sky | Free Documentary Nature, The Golden Eagle – Master of the Sky | Wildlife Documentary
Watch ‘Germany’s Wild Birds’ here: https://youtu.be/RpgWh3udd-A
When the golden eagle watches for prey while gliding over its hunting ground, hardly flapping its wings, snow and black grouse, groundhogs, hares and other animals had better watch out. Even the quick kestrel can’t escape when the golden eagle has it in its sights. The fox and the common raven may be more intelligent than the golden eagle, but if they aren’t careful they might also end up as a meal for the young eagles in the eyrie. The golden eagle is an extremely crafty hunter: optimally exploiting all cover, it glides close to the ground over knolls and low hills along hillsides and attempts to surprise its prey from a short distance. When it spies prey, it swoops down onto it in a nosedive. The eagle has already killed the surprised prey before it even realises what is happening to it.
This documentary gives an intimate portrait of this large bird of prey and tracks the birth and coming of age of two Golden Eagle chicks in the High Tatra Mountains, from the hatching of the eggs, until the moment when the young birds leave the nest. Tragic and funny moments make this movie an entertaining trip into the treetops of the European forests.
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Taxonomy and systematics
This species was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae as Falco chrysaetos. Since birds were grouped largely on superficial characteristics at that time, many species were grouped by Linnaeus into the genus Falco. The type locality was given simply as “Europa”; it was later fixed to Sweden. It was moved to the new genus Aquila by French ornithologist Mathurin Jacques Brisson in 1760. Aquila is Latin for “eagle”, possibly derived from aquilus, “dark in colour” and chrysaetos is Ancient Greek for the golden eagle from khrusos, “gold” and aetos, “eagle”.
The golden eagle is part of a broad group of raptors called “booted eagles” which are defined by the feature that all species have feathering over their tarsus, unlike many other accipitrids which have bare legs. Included in this group are all species described as “hawk eagles” including the genera Spizaetus and Nisaetus, as well as assorted monotypical genera such as Oroaetus, Lophaetus, Stephanoaetus, Polemaetus, Lophotriorchis and Ictinaetus. The genus Aquila is distributed across every continent but for South America and Antarctica. Up to 20 species have been classified in the genus, but more recently the taxonomic placement of some of the traditional species has been questioned. Traditionally, the Aquila eagles have been grouped superficially as largish, mainly brownish or dark-colored booted eagles that vary little in transition from their juvenile to their adult plumages. Genetic research has recently indicated the golden eagle is included in a clade with Verreaux’s eagle in Africa as well as the Gurney’s eagle (A. gurneyi) and the wedge-tailed eagle (clearly part of an Australasian radiation of the lineage). This identification of this particular clade has long been suspected based on similar morphological characteristics amongst these large-bodied species. More surprisingly, the smaller, much paler-bellied sister species Bonelli’s eagle (A. fasciatus) and African hawk-eagle (A. spilogaster), previously included in the genus Hieraaetus, have been revealed to be genetically much closer to the Verreaux’s and golden eagle lineage than to other species traditionally included in the genus Aquila. Other largish Aquila species, the eastern imperial, the Spanish imperial, the tawny and the steppe eagles, are now thought to be separate, close-knit clade, which attained some similar characteristics to the prior clade via convergent evolution. Genetically, the “spotted eagles” (A. pomarina, hastata and clanga), have been discovered to be more closely related to the long-crested eagle (Lophaetus occipitalis) and the black eagle (Ictinaetus malayensis), and many generic reassignments have been advocated. The genus Hieraaetus, including the booted eagle (H. pennatus), little eagle (H. morphnoides) and Ayres’s hawk-eagle (H. ayresii), consists of much smaller species, that are in fact smallest birds called eagles outside of the unrelated Spilornis serpent-eagle genus. This genus has recently been eliminated by many authorities and is now occasionally also included in Aquila, although not all ornithological unions have followed this suit in this re-classification. The small-bodied Wahlberg’s eagle (H. wahlbergi) has been traditionally considered a Aquila species due to its lack of change from juvenile to adult plumage and brownish color but it is actually genetically aligned to the Hieraaetus lineage. Cassin’s hawk-eagle (H. africanus) is also probably closely related to the Hieraaetus group rather than the Spizaetus/Nisaetus “hawk-eagle” group (in which it was previously classified) which is not known to have radiated to Africa.
Subspecies and distribution
A captive Aquila chrysaetos canadensis shows the typical rusty coloration of the subspecies.
Aquila chrysaetos homeyeri – MHNT
There are six extant subspecies of golden eagle that differ slightly in size and plumage. Individuals of any of the subspecies are somewhat variable and the differences between the subspecies are clinal, especially in terms of body size. Other than these characteristics, there is little variation across the range of the species. Some recent studies have gone so far as to propose that only two subspecies be recognized based on genetic markers: Aquila chrysaetos chrysaetos (including A. c. homeyeri) and A. c. canadensis (including A. c. japonica, A. c. daphanea and A. c. kamtschatica).
- Aquila chrysaetos chrysaetos (Linnaeus, 1758) – sometimes referred to as the European golden eagle. This is the nominate subspecies. This subspecies is found almost throughout Europe, including the British Isles (mainly in Scotland), the majority of Scandinavia, southern and northernmost France, Italy and Austria. In Eastern Europe, it is found from Estonia to Romania, Greece, Serbia and Bulgaria in southeastern Europe. It is also distributed through European Russia, reportedly reaching its eastern limit around the Yenisei River in Russia, also ranging south at a similar longitude into western Kazakhstan and northern Iran. Male wing length is from 56.5 to 67 cm (22.2 to 26.4 in), averaging 62 cm (24 in), and female wing length is from 61.5 to 71.2 cm (24.2 to 28.0 in), averaging 67 cm (26 in). Males weigh from 2.8 to 4.6 kg (6.2 to 10.1 lb), averaging 3.69 kg (8.1 lb), and females weigh from 3.8 to 6.7 kg (8.4 to 14.8 lb), averaging 5.17 kg (11.4 lb). The male of this subspecies has a wingspan of 1.89 to 2.15 m (6 ft 2 in to 7 ft 1 in), with an average of 2.02 m (6 ft 8 in), with the female’s typical wingspan range is 2.12 to 2.2 m (6 ft 11 in to 7 ft 3 in), with an average of 2.16 m (7 ft 1 in). This is a medium-sized subspecies and is the palest. As opposed to golden eagles found further east in Eurasia, the adults of this subspecies are a tawny golden-brown on the upperside. The nape patch is often gleaming golden in color and the feathers here are exceptionally long.
- Aquila chrysaetos homeyeri Severtzov, 1888 – commonly known as the Iberian golden eagle. This subspecies occurs in almost the entirety of the Iberian peninsula as well as the island of Crete, though it is absent from the rest of continental Europe. It also ranges in North Africa in a narrow sub-coastal strip from Morocco to Tunisia. A completely isolated population of golden eagles is found in Ethiopia‘s Bale Mountains, at the southern limit of the species’ range worldwide. Although this latter population has not been formally assigned to a subspecies, there is a high probability that it belongs with A. c. homeyeri. This subspecies also ranges in much of Asia Minor, mainly Turkey, spottily through the Middle East and the Arabian Peninsula into northern Yemen and Oman to its eastern limits throughout the Caucasus, much of Iran and north to southwestern Kazakhstan. Male wing length is from 55 to 64.3 cm (21.7 to 25.3 in), averaging 59 cm (23 in), and female wing length is from 60 to 70.5 cm (23.6 to 27.8 in), averaging 64 cm (25 in). Weight is from 2.9 to 6 kg (6.4 to 13.2 lb) with no known reports of average masses. This subspecies is slightly smaller and darker plumaged than the nominate subspecies, but it is not as dark as the golden eagles found further to the east. The forehead and crown are dark brownish, with the nape patch being short-feathered and a relatively light rusty color.
- Aquila chrysaetos daphanea Severtzov, 1888 – known variously as the Asian golden eagle, Himalayan golden eagle or berkut. This subspecies is distributed in central Kazakhstan, eastern Iran, and the easternmost Caucasus, distributed to Manchuria and central China and along the Himalayas from northern Pakistan to Bhutan and discontinuing in northeastern Myanmar (rarely ranging over into northernmost India). This subspecies is the largest on average. Male wing length is from 60 to 68 cm (24 to 27 in), averaging 64 cm (25 in), and female wing length is from 66 to 72 cm (26 to 28 in), averaging 70 cm (28 in). No range of body weights are known, but males will weigh approximately 4.05 kg (8.9 lb) and females 6.35 kg (14.0 lb). Although the wingspan of this subspecies reportedly averages 2.21 m (7 ft 3 in), some individuals can have much longer wings. One female berkut had an authenticated wingspan of 2.81 m (9 ft 3 in), although she was a captive specimen. It is generally the second-darkest subspecies, being blackish on the back. The forehead and crown are dark with a blackish cap near the end of the crown. The feathers of the nape and top-neck are rich brown-red. The nape feathers are slightly shorter than in the nominate subspecies and are similar in length to A. c. homeyeri.
- Aquila chrysaetos japonica Severtzov, 1888 – commonly known as the Japanese golden eagle. This subspecies is found in northern Japan (the islands of Honshu, Hokkaido and discontinuously in Kyushu) and undefined parts of Korea. Male wing length is from 58 to 59.5 cm (22.8 to 23.4 in), averaging 59 cm (23 in), and female wing length is from 62 to 64.5 cm (24.4 to 25.4 in), averaging 63 cm (25 in). No range of body weights are known, but males will weigh approximately 2.5 kg (5.5 lb) and females 3.25 kg (7.2 lb). This is, by far, the smallest-bodied subspecies. It is also the darkest, with even adults being a slaty-grayish black on the back and crown and juveniles being similar, but with darker black plumage contrasting with brownish color and white scaling on the wings, flank and tail. This subspecies has bright rufous nape feathers that are quite loose and long. Adult Japanese golden eagles often maintain extensive white mottling on the inner-webs of the tail that tend to be more typical of juvenile eagles in other subspecies.
- Aquila chrysaetos canadensis (Linnaeus, 1758) – commonly known as the North American golden eagle. Occupies the species’ entire range in North America, which comprises the great majority of Alaska, western Canada, Western United States and Mexico. The species is found breeding occasionally in all Canadian provinces but for Nova Scotia. It is currently absent in the Eastern United States as breeding species east of a line from North Dakota down through westernmost Nebraska and Oklahoma to West Texas. The southern limits of its range are in central Mexico, from the Guadalajara area in the west to the Tampico area in the east; it is the “Mexican eagle” featured on the coat of arms of Mexico. It is the subspecies with the largest breeding range and is probably the most numerous subspecies, especially if A. c. kamtschatica is included. Male wing length is from 59.1 to 64 cm (23.3 to 25.2 in), averaging 61 cm (24 in), and female wing length is from 60.1 to 67.4 cm (23.7 to 26.5 in), averaging 65 cm (26 in). The average wingspan in both sexes is about 2.04 m (6 ft 8 in). Males weigh from 2.5 to 4.47 kg (5.5 to 9.9 lb), averaging 3.48 kg (7.7 lb), and females typically weigh from 3.6 to 6.4 kg (7.9 to 14.1 lb), averaging 4.91 kg (10.8 lb). The subspecies does not appear to follow Bergmann’s rule (the rule that widely distributed organisms are larger-bodied further away from the Equator), as specimens of both sexes from Idaho had a mean weight of 4.22 kg (9.3 lb) and where slightly heavier than those from Alaska, with a mean weight of 3.76 kg (8.3 lb). It is medium-sized, being generally intermediate in size between the nominate and A. c. homeyeri, but with much overlap. It is blackish to dark brown on the back. The long feathers of the nape and top-neck are rusty-reddish and slightly narrower and darker than in the nominate subspecies.
- Aquila chrysaetos kamtschatica Severtzov, 1888 – sometimes referred to as the Siberian golden eagle or the Kamchatkan golden eagle. This subspecies ranges from Western Siberia (where overlap with A. c. chrysaetos is probable), across most of Russia, including the Altay (spilling over into Northern Mongolia), to the Kamchatka Peninsula and the Anadyrsky District. This subspecies is often included in A. c. canadensis. Male wing length is from 61.8 to 70.5 cm (24.3 to 27.8 in), averaging 64 cm (25 in), and female wing length is from 65 to 72 cm (26 to 28 in), averaging 69 cm (27 in). No weights are known in this subspecies. The coloration of these eagles is almost exactly the same as in A. c. canadensis. The main difference is that this subspecies is much larger in size, being nearly the equal of A. c. daphanea if going on wing-length.
The larger Middle Pleistocene golden eagles of France (and possibly elsewhere) are referred to a paleosubspecies Aquila chrysaetos bonifacti, and the huge specimens of the Late Pleistocene of Liko Cave (Crete) have been named Aquila chrysaetos simurgh (Weesie, 1988). Similarly, an ancestral golden eagle, with a heavier, broader skull, larger wings and shorter legs when compared to modern birds, has been found in the La Brea Tar Pits of southern California.
A golden eagle lands on carrion during a snowstorm.
At least seven main hunting techniques are known to be utilized by the species, with many individual variations and the ability in most mature eagles to quickly (and sometimes cleverly) vary back and forth between methods depending on the circumstance. The first described is “high soar with glide attack”, where the golden eagle soars at least 50 m (160 ft) above the earth. Once it spies a prey item, the eagle partially closes its wings and enters a long, low-angled glide which can carry it over distances of 1 km (0.62 mi) with the speed increasing as the wings close more. Just prior to impact, the wings are opened, the tail fanned and feet thrust forward to grab the prey, creating a booming sound, causing by the wings whipping against the wind, in the instant before the strike that sounds like a clap of thunder. This technique is used for solitary or widely dispersed prey found in openings, such as hares or ptarmigans. A variation of the high soar where a lofty perch is used instead of soaring flight has been observed.
The next major hunting methods is the “high soar with vertical stoop”, which is used to attack birds in flight. Since they are outpaced and out-maneuvered by swift-flying birds, they can only usually attack slower-flying species such as geese and cranes. The golden eagle also requires a height advantage over their prey for this rarely observed technique to succeed. In one observed case, some Canada geese (Branta canadensis) in Montana were able to avoid predation by a golden eagle hunting them in this way by collectively gaining flying height. In another observation, a golden eagle was successful in knocking a ptarmigan out of a flying covey in Scotland.
The next hunting method is the “contour flight with short glide attack”, which is considered the most commonly utilized hunting method for golden eagles. This consists of a low-level quartering flight often at only 5 to 15 m (16 to 49 ft) above the ground so they do not break the sky-line when observed from the ground and they can hug the contours of the earth below. This method is useful for hunting colonial (often burrowing) prey such as ground squirrels, densely populated leporids or birds found in concentrations, such as breeding grouse or even seabirds. The individual prey item is apparently selected in a manner of seconds before the strike. If the first attempt fails, the eagle may fly around and attempt to ambush the prey again.
The next hunting method is the “glide attack with tail-chase”, which commences with a low-angled stoop some distance from the quarry. The prey is then chased closely, whether a hare running evasively or a grouse in flight. The key to success is eagle’s agility and the prey’s inability to find cover. In one case, a flying greater sage-grouse (Centrocercus urophasianus) was caught by a pair of eagles using this technique.
The next major hunting method is “low flight with slow descent attack”. In this, the golden eagle quarters low below the earth and then gradually swoops down on the prey. This is used for slow-moving prey, such as tortoises and hedgehogs, or any prey item with a general absence of escape behavior. This includes any potentially dangerous prey items, such as rattlesnakes and foxes. When hunting mammalian carnivores, the eagle may hover for some time over the potential prey and not press the attack unless the mammal looks down.
The next is the “low flight with sustained grip attack”, which is used for hunting ungulates. Here, the golden eagle flies over a herd of ungulates which in turn often huddle or break into a run. The eagle then selects it prey (typically young animals, though sometimes infirm or exceptionally healthy grown animals) and lands on prey’s back or neck, talons gripping firmly, attempting to pierce vital organs or cause shock via a crushing grip to bone and cartilage. The hunting eagle typically rides its prey for several minutes with wings outstretched and flapping to maintain balance until the prey collapses, either as result of exhaustion, shock or internal injury.
The final major hunting method is the “walk and grab attack”, in which the eagle walks on the ground and attempts to pull its prey out of cover. This has been used for pulling jackrabbits out of brush but has even been utilized to grab the young of large prey (i.e. deer, sheep and badgers) from under the mother’s legs. Tandem hunting may be done regularly, especially with larger prey items. Reportedly, while hunting in pairs, the male golden eagle flies in front of the female at a higher elevation and usually initiates the attack. Breeding pairs have been recorded hunting jackrabbits cooperatively with one individual following the other at different elevations above the ground. The initial pursuer diverts the prey’s attention by stooping while the second flies in unseen to make the kill. A study in Idaho showed that the success rate was lower during tandem hunting (9%) than during solo hunting (29%), but this may have been due to the more difficult nature of the prey targeted during tandem hunts. As a whole birds are reportedly more difficult prey to capture than mammals, so hunting success rates may be lower where birds outrank mammals in importance as prey. Golden eagles are not above scavenging for carrion. In fact, it makes up a significant portion (sometimes a majority) of the diet in winter, when ground squirrels are in hibernation and rabbits and hares tend to be at population lows. In the Greater Yellowstone area, the golden eagle was one of the most frequent scavengers to attend wolf kill-sites in winter but, unlike common ravens (Corvus corax) and bald eagles, were not frequent at kills left out by human hunters. In many parts of the range (i.e. Alberta, Scotland, Spain, etc.) carrion was readily fed to the young during the breeding season.
Size and taxonomy
Mountain hawk-eagles are the largest and most robust of the hawk-eagles in the genus Nisaetus.
The mountain hawk-eagle is a large raptor and fairly large eagle. Although described not infrequently as “slim”, it is usually perceptibly bulkier and more massive than most other members of its genus. It is seemingly the largest member of the 10 currently recognized species in the genus Nisaetus, notwithstanding the recently recognized Flores hawk-eagle (Nisaetus floris) (which was separated from the changeable hawk-eagle). The latter critically endangered island hawk-eagle seems to be of broadly similar size (weight is unknown), albeit with shorter wings, however the Flores species seems to be linearly outmatched by the largest mountain hawk-eagle. The mountain hawk-eagle attains a total length of 69 to 84 cm (27 to 33 in) and a wingspan of 134 to 175 cm (4 ft 5 in to 5 ft 9 in). Like most birds of prey, females are larger on average than the male, with a typical size difference of 3-8%, though it can rarely range up to a 21% difference. Although its wings are relatively short compared to eagles of open country, it has the longest wings of any of the hawk-eagles, even relative to their size. Mountain hawk-eagles have a short but strong bill, long and often erect crest (though can also be very short), short wings, a longish three-banded tail, feathered legs and powerful feet. It is usually rather unobtrusive, perching rather upright inside of canopy, with its wing-tips coming to less than one-fifth down the tail. There are two currently recognized races of the mountain hawk-eagle: the nominate subspecies (N. n. nipalensis) and the subspecies native to Japan (N. n. orientalis). The nominate race is found throughout mainland range and includes the likely dubious southeast Chinese races of N. n. fokiensis and N. n. whiteheadi. The average total length of the nominate subspecies is estimated to be 72 cm (28 in). Among standard measurements in the nominate race, the wing chord of males ranges from 410 to 465 mm (16.1 to 18.3 in) while the female’s ranges from 445 to 508 mm (17.5 to 20.0 in). In both sexes, the tail ranges from 279 to 314.3 mm (10.98 to 12.37 in) and the tarsus from 100 to 119.9 mm (3.94 to 4.72 in). 9 males of the nominate race were found to average 437.2 mm (17.21 in) in wing length, 281.3 mm (11.07 in) in tail length, 38.7 mm (1.52 in) in hallux claw length (the large rear talon often utilized by accipitrids as a killing tool), 110.3 mm (4.34 in) in tarsus length and 30.3 mm (1.19 in) in bill length. 13 females of the nominate were found to average 479.2 mm (18.87 in) in wing length, 297.9 mm (11.73 in) in tail length, 46 mm (1.8 in) in hallux claw length, 114.8 mm (4.52 in) in tarsus length and 33.9 mm (1.33 in) in bill length. One unsexed mountain hawk-eagle from northern India was found to weigh 1.83 kg (4.0 lb). A single male from the Yangtze area of east-central China was found to have weighed 2.8 kg (6.2 lb) while two females from there weighed 2.95 and 3.5 kg (6.5 and 7.7 lb), suggesting size increases further north in this subspecies in accordance with Bergmann’s rule.
The Japanese race averages about 9% larger than mainland race, and also has a proportionately longer tail and longer wings. The populations from Taiwan and the possible ones in Hainan are also probably part of this race. N. n. orientalis is generally paler than the nominate race with less heavy markings below. The underside in this race has a paler ground colour against much browner and darker barring, often showing less of the warmer or rufous tones typical of mainland mountain hawk-eagles. The throat often has reduced blackish streaking compared to mainland birds and the upper chest can be whitish and nearly unmarked. N. n. orientalis has black mottled or light streaked wing-linings and a small, often vestigial crest compared to the rather ample one of the mainland birds. Sometimes, N. n. orientalis is hypothesized to be a separate species. Among standard measurements wing chord of males ranges from 470 to 518 mm (18.5 to 20.4 in) while the female’s ranges from 500 to 540 mm (20 to 21 in). In both sexes, the tail ranges from 325 to 395 mm (12.8 to 15.6 in) and the tarsus from 104 to 128.9 mm (4.09 to 5.07 in). From a sample of unknown size from the Suzuka Mountains, males of N. n. orientalis were found to average 71.4 cm (28.1 in) and females 76.3 cm (30.0 in) in total length. From the same sample, males had a mean wing chord length of 488 mm (19.2 in), tail length of 342 mm (13.5 in), culmen length of 34 mm (1.3 in) and tarsus length of 113 mm (4.4 in). Meanwhile, females had a mean wing chord length of 516 mm (20.3 in), tail length of 356 mm (14.0 in), culmen length of 37 mm (1.5 in) and tarsus length of 118.2 mm (4.65 in). Perhaps most surprisingly, the Suzuka mountain birds were not noticeably discrepant in body mass from known weights of mainland mountain hawk-eagles, especially similar to that of the apparently larger hawk-eagles from east-central China. The Suzuka sample as above found males to weigh from 2.2 to 2.7 kg (4.9 to 6.0 lb), with an average of 2.3 kg (5.1 lb), while females were found to weigh from 2.5 to 3.9 kg (5.5 to 8.6 lb), with an average of 3.1 kg (6.8 lb). Another Japanese survey found the smallest male to weigh 1.68 kg (3.7 lb), the lightest known weight known anywhere for the species.
Drawing of the Japanese race by Kawahara Keiga, from the early 1800s.
At one time largish hawk-eagles found in Sri Lanka and southwestern India was deemed to be part of the mountain hawk-eagle species under the subspecies N. n. kelaarti. A 2008 study based on the geographic isolation and differences in call suggest that this be treated as a full species, Nisaetus kelaarti, Legge’s hawk-eagle. The full species status of Legge’s hawk-eagle appears to be further supported by DNA studies, with an average difference in mitochondrial DNA of 4.3% (usually the minimum difference to differentiate species is considered to be 1.5%). Although extremely isolated in distribution from true mountain hawk-eagles, Legge’s hawk-eagle is physically distinct as well, often being much paler and less marked below with the throat stripes characteristics of the mountain species often absent (occasionally faint stripes may manifest) being instead largely plain buff about the throat. Like mainland mountain hawk-eagles, Legge’s hawk-eagles have a strong crest. The hand in flight on a Legge’s is often plain buff in colour (or with some very faint streaking) and the banded wing feathers are rather faded. Legge’s hawk-eagle appears to be about 10% smaller than mountain hawk-eagles and was found to differ in almost all bodily proportions from mountain hawk-eagle, with relatively smaller wings but the smaller species also has a larger bill and larger talons than the mountain hawk-eagle.
A subadult mountain hawk-eagle in flight in Singapore.
Colouring and confusion species
Adult mountain hawk-eagles are dark brown above with slightly paler edges, which tend to be clearest on median and greater coverts. On adults, the head is fairly rusty above with strong black streaks, though the volume of streaks tends to decrease on the neck, which in turn may suggest a rufous collar. The crest is largely black with a small buffy tip. Their tail is grey-brown, with a whitish tip and rather obscure blackish banding above. The malar area and throat are marked with blackish, ragged and sparse but rather bold stripes which contrast with the rest of their underside which is predominantly barred with rufous over a whitish ground colour. The barring continues, though the white base colour narrows and the rufous becomes a somewhat browner hue, down to the crissum and the legs. In some cases, the colour about the legs has appeared variously chestnut or even blackish. The underside of the tail is boldly banded with blackish and grey. The juvenile mountain hawk-eagle is also dark brown above but usually has clear cream to whitish feather edges causing the wing coverts to have a scaled effect; meanwhile, the feather bases of median and greater coverts form tawnier mid-wing patches. The juvenile’s tail is thinly banded alternately with lighter and darker brown but usually have a whitish tip like the tail of the adult. The juvenile mountain hawk-eagle’s underside is all plain buffy to tawny. The underside colour also extends to the head and part of the neck flanks while the crown, cheek, nape and hind-neck all streaked with dark brown. The crest is black with a small white tip. The juvenile leg feathers are whitish. The markings on the underside begin to develop by the 2nd year, starting from the flanks and gradually increasing inward to the breast, but the young hawk-eagles are still quite paler below until their 3rd year, which is also when the tail starts to resemble the adults. Full adult plumage is attained at no later than the 4th year. Adults have golden or even yellowish-orange eyes, with juveniles having pale bluish-grey to pale yellow eyes. In the adult the cere is blackish-grey, while in juveniles it is dull-grey. In all ages, the feet range from dull yellow to yellowish white. In flight, it is notable for its rather prominent head and relatively short rounded wings, an effect emphasized by their broad hands and bulging secondaries, which tend to pinch in at the rear bases. The mountain hawk-eagle is capable of fast, agile flight “with astonishing maneuverability”. They usually glide with powerful, shallow beats interspersed with glides on level wings, but soaring birds hold their wings in a shallow V, pressed slightly forward. The wing linings of adults are a rusty similar to flank coloring, becoming paler on forepart and marked with dusky mottling which becomes darker mid-wing. Blackish-brown bars are apparent over greyish ground colour on the secondaries, the feathers here relatively broadly barred with blackish while the primaries are whiter based and darker tipped. Flying juveniles are fairly heavily mottled with white above. Juveniles show more buff to tawny colour below extending to their wing linings while the wing-tips are black, in some cases extending to primary coverts form a vague carpal arc. Juvenile flight feathers are whitish grey with thin and rather faded looking dusky barring, with less white showing at the base of the primaries. Juveniles in flight usually evidence a less distinct subterminal band than do adults.
Close-up of a mountain hawk-eagle from China.
Confusion of mountain hawk-eagle in all plumages is possible with pale morph changeable hawk-eagles (Nisaetus cirrhatus). However, the latter species only has a vestigal crest in most areas of overlap from northern India to southeast Asia. Furthermore, the changeable is a slighter, more slender bird with a relatively longer tail. The latter species also has narrower wings with more even trailing edges. While soaring, changeable hawk-eagles tend to have flatter wing shape than mountain hawk-eagles. Changeable adults also have streaking rather than heavy rusty barring on their underside, apart from subtle parts of wing linings and flanks, and also have narrower tail bars. In flight, the changeable also has clear white base to their primaries and less whitish on the rump when seen from above. Juveniles of the two species are more easily mistaken but wing proportions always differ, the mountain juveniles usually appear perceptibly bulkier and changeable juveniles (of relevant races) are generally much paler, rather than warm buffy to tawny, on the head and underparts. The mountain hawk-eagle also overlaps somewhat in range, in southeast Asia, with Blyth’s hawk-eagle (Nisaetus alboniger) and Wallace’s hawk-eagles (Nisaetus nanus) but both are much smaller and different in multiple ways (especially the bold black-and-white of adult Blyth’s). Another, albeit unlikely, potential source of confusion for the mountain hawk-eagle is with Jerdon’s baza (Aviceda jerdoni), which is far smaller, and of a far more compact and chunky build. The baza is somewhat similar in marking to adult mountain hawk-eagles, but the baza lacks feathered legs and has relatively much longer and differently shaped wings. Mountain hawk-eagles can usually be told from the slighter, smaller crested honey buzzard (Pernis ptilorhynchus), beyond the latter being polymorphic, as even most similarly plumaged individual honey buzzards have bare legs, much smaller and slimmer head and bill with a longer neck and deeper wing beats on relatively longer, more slender wings.
Mountain hawk-eagles are silent apart from their breeding season. Their call is a shrill treble note, with a quality often compared to a penny whistle. Their typical call is often likened to the klu-weet-weet of a green sandpiper (Tringa ochropus) or the kee-kikik of the common green magpie (Cissa chinensis). Sometimes the call is written in Japan as pie-pie-pie or pipipi. The hawk-eagles, including both members of a breeding pair, may call both in flight and while perched. Another call of a rapid bubbling quality, which is considered comparable to that of the little grebe (Tachybaptus ruficollis), is probably produced only during sky-dances. A study in Taiwan diagnosed seven call types consisting of different quality trills in Taiwan during the breeding cycle, including different calls emitted during flight or while perched and food-begging or alarm calls by nestlings. The calls of mountain hawk-eagles are said to be expertly mimicked by drongos in some parts of the range.
The Ancient Egyptian sun god Horus was depicted as having the head of a falcon, and was important as a deity representing the Pharaoh. Horus played an important role, too, as representing resurrection, being the son of his mummified father Osiris and mother Isis. The Greeks and Romans believed Zeus and Jupiter respectively to be represented by the eagle.
Russian depiction of Mongolian falconers fox-hunting with a golden eagle.
Golden eagles can be trained to be highly effective falconry birds, though their size, strength, and aggressiveness require careful handling to control the risk of injury to the falconer. They have been used in this practice at least since the Middle Ages. In Asia, they were reportedly used in teams to hunt such animals as deer, antelope and wolves. Concurrently in Europe, their use for falconry was typically reserved for Emperors and Kings, which is why the common names for the golden eagle in various European languages roughly translate as the “royal eagle”. In the United States falconers seldom use golden eagles, as the similarly aggressive Ferruginous hawk is more available and provides a similar hunting experience with most of the same game species with lower risk of injury to the falconer. The most common interaction of American falconers with golden eagles is in trying to avoid them in order to reduce golden eagle attacks on their trained birds. The very athletic golden eagle is approximately as swift as the large falcons, is quite willing to attack smaller raptors when the opportunity is available, and is often capable of flying down a falcon or hawk. Experienced falconers will consequently not fly their birds if golden eagles are spotted, and usually prefer to fly later in the day when the golden eagles have typically already fed.
The culture in which falconry with golden eagles is prominent today is amongst the Kyrgyz people of the Tien Shan Mountains of southeastern Kazakhstan and Kyrgyzstan. This practice is also culturally prominent in western Mongolia and Xinjiang. There are around 250 active eagle hunters in Bayan-Ölgii Province of Mongolia, and 50 in Kazakhstan. In these cultures, the golden eagle is considered a highly valued working animal which will be used for 15 years or more. Falconers carry their bird on a gloved right hand, usually with a wooden brace to support its considerable weight. In the Tien Shan Mountains, falconry mostly occurs in late fall and early winter. It is possible for up to 30 to 50 foxes to be caught by a single eagle during this season.
Full-grown wolves are not believed to be viable prey for wild golden eagles; they are too dangerous due to their large size and large, powerful bite. Despite this, falconers occasionally use golden eagles to hunt wolves. The steppe wolf (Canis lupus campestris), a relatively small-bodied race of wolf at around 35 kg (77 lb), is the main wolf reportedly hunted by golden eagles in falconry. There are records that some experienced golden eagles successfully kill subadult or even adult wolves. However, even a well-trained golden eagle has a risk of injury so most falconers do not risk casting a mature eagle at an adult wolf.
Some wolves prove particularly challenging quarry: there is the tale of one that was injured by 11 successive eagles but foiled their attempts – killing each one – until it was finally dispatched thanks to the efforts of a twelfth eagle.
Golden Eagle Photos and Videos
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The Four Keys to ID
- Size & Shape
Golden Eagles are one of the largest birds in North America. The wings are broad like a Red-tailed Hawk’s, but longer. At distance, the head is relatively small and the tail is long, projecting farther behind than the head sticks out in front.
goose-sized or larger
- Both Sexes
- Length: 27.6-33.1 in (70-84 cm)
- Weight: 105.8-216.1 oz (3000-6125 g)
- Wingspan: 72.8-86.6 in (185-220 cm)
- Color Pattern
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Searches for prey by soaring high or by flying low over slopes; also watches for prey from high perches. When prey is spotted, eagle plunges to capture it in talons. Members of a pair sometime hunt together, with the second bird capturing prey that evades the first.
2, sometimes 1-3, rarely 4. Whitish to buff, marked with brown. Sometimes one egg in the clutch is unmarked. Incubation is by both parents (female does more), 41-45 days. Young: Female remains with young most of the time at first, while male does most hunting, bringing prey to nest. After young are half-grown, female also does much hunting. Age of young at first flight roughly 60-70 days.
Female remains with young most of the time at first, while male does most hunting, bringing prey to nest. After young are half-grown, female also does much hunting. Age of young at first flight roughly 60-70 days.
Mostly small mammals. Typically preys on mammals ranging in size from ground squirrels up to prairie-dogs, marmots, and jackrabbits. May take smaller rodents (voles and mice) or larger animals such as foxes, young pronghorns, or young deer on occasion. Also eats birds, mostly gamebirds such as grouse but rarely birds as large as cranes or as small as sparrows. Also some snakes, lizards, large insects. Will feed on carrion, including dead fish.
May mate for life. In courtship, 2 birds circle high in air, making shallow dives at each other. Display to defend territory includes repeated high flight followed by steep dives, loops, rolls, and other acrobatics. Nest site is most often on cliff ledge, also frequently in large tree, rarely on ground. Sites may be used for many years. A pair may have 2 or more alternate nest sites, using them in different years. Nest (built by both sexes) a bulky platform of sticks, lined with weeds, grass, leaves, moss. New material added each year, and nest may become huge.
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