Family Hawks, Eagles (Accipitridae)

Least Concern

Golden Eagle (Aquila chrysaetos)

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Taxonomy

French: Aigle royal German: Steinadler Spanish: Águila real
Taxonomy:

Falco Chrysaëtos

Linnaeus

, 1758,

Sweden

.

Has been considered closely related to A. audax, and perhaps also to A. gurneyi. Form kamtschatica very similar to canadensis and often synonymized with it. Ethiopian population provisionally included in homeyeri, but racial affinity requires investigation. A recent mitochondrial DNA analysis based on a large number of samples across the species’ distribution reveals Holarctic homogeneity and a distinct Mediterranean lineage: there is a phylogeographic split between mainly Northern Europe, Continental Asia, Japan and North America on the one hand and Central–Southern Europe on the other, this being likely caused by the Last Ice Age, when the population survived in two reproductively isolated glacial refugia; repopulation of Northern Europe occurred from a presumed Asian refugium, whereas the Alpine range was probably repopulated from a refugium in the Mediterranean region#R. Six subspecies normally recognized.

Subspecies and Distribution
  • A. c. chrysaetos (Linnaeus, 1758) – NW & C Europe E to W & C Siberia and Altai.
  • A. c. homeyeri Severtsov, 1888 – Iberian Peninsula, N Africa (also scattered in mountains in S Sahara#R) and large Mediterranean islands E through Middle East and Arabia to Caucasus, Iran and E Uzbekistan; possibly this subspecies in Ethiopia.
  • A. c. daphanea Severtsov, 1888 – mountains of C Asia and Himalayas (N Pakistan to Bhutan) to W & C China.
  • A. c. kamtschatica Severtsov, 1888 – W & C Siberia and Altai E to Kamchatka and Russian Far East.
  • A. c. japonica Severtsov, 1888 – Korea and Japan.
  • A. c. canadensis (Linnaeus, 1758) – North America from Alaska and NW Canada S through W USA to C Mexico, and NE Canada E to N Quebec and Labrador; winters locally throughout E USA.
  • Descriptive notes

    66–90 cm#R; male 2840–4550 g, female 3630–6665 g (exceptionally up to c. 7200 g#R); wingspan 180–234 cm#R. Fairly uniform dark brown although crown, nape and median upperwing coverts normally pale yellowish-tawny. Female averages 10% larger and up to 50% heavier than male#R. Juvenile darker chocolate brown, with characteristic white bases to flight feathers; tail basally white, with dark terminal band; white areas of plumage progressively replaced with brown over 4–5 years, although full adult plumage not until 6–8 years. Races vary slightly in size and coloration, particularly in darkness of plumage and extent and shade of pale areas; crown and nape, at least rear portion, always clearly paler, ranging from yellowish to rufous-brown.

    Drawing by Ian Willis
    Descriptive notes:

    66–90 cm#R; male 2840–4550 g, female 3630–6665 g (exceptionally up to c. 7200 g#R); wingspan 180–234 cm#R. Fairly uniform dark brown although crown, nape and median upperwing coverts normally pale yellowish-tawny. Female averages 10% larger and up to 50% heavier than male#R. Juvenile darker chocolate brown, with characteristic white bases to flight feathers; tail basally white, with dark terminal band; white areas of plumage progressively replaced with brown over 4–5 years, although full adult plumage not until 6–8 years. Races vary slightly in size and coloration, particularly in darkness of plumage and extent and shade of pale areas; crown and nape, at least rear portion, always clearly paler, ranging from yellowish to rufous-brown.

    Voice

    Usually vocal only around nesting territory. Main call a shrill “kee-yep” or “yep”, either given singly or in rapid series. In aerial display, a combined series of yelps and Buteo-like mewing notes, e.g. “wee-o hyo hyo...wee-o...”#R.

    Habitat

    Uses a wide variety of open habitats, usually away from humans, e.g. mountains, plateaux and steppes; locally marshy areas; prefers low or sparse vegetation to wooded areas. From desert areas to edge of tundra, and from sea-level high into mountains; frequents alpine levels, especially in summer. Nests from near sea-level up to considerable elevations, occasionally above 2000 m in Alps and Pyrenees; may occur over 5500 m in Himalaya, roughly up to summer snow line. Normally requires remote, peaceful sites for nesting, e.g. rock faces, large trees; perches on vantage points on rocks or trees. Nesting birds favour sagebrush (Artemisia) habitats in aridlands of Idaho, USA, because they contain the best numbers of black-tailed jackrabbits (Lepus californicus)#R.

    Food and feeding

    Prefers medium-sized mammals, mainly rodents, rabbits and hares; also, normally to lesser degree, birds, particularly gamebirds, including large grouse; much less frequently lizards and snakes; also carrion, especially in winter. Hares (Lepus), rabbits (Sylvilagus), ground squirrels (Spermophilus) or, in mountainous areas, marmots (Marmota) tend to be most numerous mammal prey#R; domestic stock (e.g. sheep) and wild ungulates (e.g. deer) may be important in diet as carrion, whereas young and vulnerable animals are sometimes hunted, e.g. reindeer (Rangifer tarandus) calves in N Finland#R and subadult sika deer (Cervus nippon) in Russia#R; carnivores (mustelids, foxes, cats, etc.) are sometimes taken regularly. Avian prey range in size from small passerines up to cranes, storks or swans, but species prefers galliforms such as grouse, pheasants and partridges. One documented case of adult flushing incubating Canada Goose (Branta canadensis) from ground nest and then breaking open and consuming two goose eggs#R. Unusual prey at a nest in Mongolia included Upland Buzzard (Buteo hemilasius), Demoiselle Crane (Anthropoides virgo), Eurasian Eagle-owl (Bubo bubo), Common Raven (Corvus corax), Pallas’s cat (Felis manul) and Mongolian gazelle (Procapra gutturosa)#R. Recent suggestions that this eagle could suffer adverse effect in Scotland from reintroduced population of Haliaeetus albicillaappears unfounded: there it fed chiefly on gamebirds (Galliformes), lagomorphs and other terrestrial prey, whereas H. albicilla took more sheep and aquatic/coastal food items, and no evidence that latter had any long-term effect on breeding productivity of present species#R. Normally captures prey on ground, using low hunting flight. Sometimes pair members hunt together. In some areas captures tortoises, dropping them on to rocks to break shells. In W Iran, diet of nesting birds consisted of 44% birds (mostly Alectoris chukar and Pica pica), 44% mammals (mostly Lepus capensis, Spermophilus fulvus and Vulpes vulpes), 11% reptiles and small numbers of insects#R. One known direct observation of insectivory wherein adult walked in grassy field and captured grasshoppers (Locustidae) in its bill during nesting season in California#R. Consumes snow at high elevations in arid W USA in summer, presumably as source of free water#R.

    Breeding

    Laying starts Feb in S Europe and S North America, until May in more N regions. Nests on ledges of cliffs and crags, or in trees, tendency varying regionally. In Montana, USA, daily nest survival statistically equal at cliff and tree nests#R. Eyries traditional; normally several per pair, which are used alternately#R. In long-term study in Utah, USA, occupied territories had 1–8 nests spaced an average of 0·5 km apart; individual nests received eggs every 3·3 years; 43·3% of consecutive nesting attempts on a territory were in different nests#RLarge nest of sticks and branches lined with greenery, up to 200 cm wide and deep; nest height exceptionally up to 7 m in cases of nest reuse over many decades#R. Normally 2 eggs (1–3), laid at interval of c. 3 days; incubation c. 41–45 days per egg, almost exclusively by female; hatching asynchronous; chicks have first and second downs white or whitish; younger chick often dies due to older sibling's attacks; fledging 65–80 days. Young can be dependent on adults and fed by them for some months, and sometimes tolerated in adults' home range until following season; however, in migratory population in Alaska, USA, 44 nestlings fitted with satellite transmitters were dependent on parents for only 39–63 days#R. From 1–3 chicks fledge, normally 1, very rarely 3; one case of bigamy with 4 chicks raised; mean 0·4–1·3 per breeding pair, and 1·0–1·6 per successful pair, but wide range. Failure or non-breeding are common, sometimes occurring in 50% or more of pairs; success influenced by food supply and weather; sometimes declines if reaches very high densities. Possibly only 25% of chicks reach maturity, due to starvation, accidents with powerlines, shooting, etc. Adults typically begin nesting at 4 or 5 years old, exceptionally at slightly less than 3 years old#R. Birds live up to 38 years in wild, and up to 50 years in captivity.

    Movements

    Some populations sedentary, others migratory. In northernmost parts of range in North America and Eurasia, generally migratory where prey may become scarce or inaccessible in winter (e.g. hibernating ground squirrels). In W North America, migrants leave breeding grounds in Sept or Oct; most winter in W USA, but some winter S to Mexico in areas with resident populations too; return starts Feb, and lasts months, with juveniles returning latest. Breeders from N Quebec, Canada, fitted with satellite transmitters left the nesting grounds from mid- to late Oct and wintered in E USA; northward migration commenced in Mar#R. Fourteen fall-migrant adults fitted with satellite transmitters in Montana from 2008–2012 wintered at various locations that included Montana, Idaho, Wyoming, Colorado, New Mexico, and Texas#R. Stable hydrogen isotopes in feather samples of 50 juveniles captured during southward migration in Montana from 2004–2007 indicated that most of the birds had hatched at northern latitudes from E Alaska and Yukon to W Northwest Territories, Canada#R. Sixty nestlings from the SW USA tagged with satellite transmitters dispersed from natal areas between mid-Sept and late Nov; 67% settled within 120 km of their nests in the first year post-fledging, and only 13% moved more than 500 km (maximum = 1379 km)#R. Passage rates of migrants over Glacier National Park, Montana, increased with rising air temperature and barometric pressure in fall and with increasing wind speed and rising barometric pressure in spring#R. Sedentary adult pairs normally stay in approximately same home range throughout year. Juveniles markedly more dispersive and travel further. Among radio-tracked migratory birds in E North America, in spring adults depart earlier and spend less time migrating, while in autumn birds of all age-classes increase the length of stopovers, fly less direct routes and migrate at a slower pace than during spring; directness of migratory flight is in both seasons lowest in juveniles, intermediate in sub-adults and highest in adults#R.

    Status and conservation

    Not globally threatened (Least Concern). CITES II. Heavily persecuted in past, with declines in range and numbers in Europe and much of North America, often from 19th century, and mainly due to direct persecution and poisoned baits. Banning of poisons and protection have permitted increase or at least stabilization in many countries, but recolonization has not yet reached all of original range, e.g. still very localized in C Europe and E USA; moreover, exposure to anticoagulant rodenticides remains a problem in the USA#R. Ongoing persecution of breeding adults in Scotland (from shooting and illegal poisoning#R), even at fairly low levels, could be sufficient to cause negative population trend#R. Lead poisoning, mostly from ammunition in carcasses of hunter-killed mammals, continues to cause direct mortality in Eurasia and North America#R#R#R. In Europe at end of 1980s, total population c. 4500–5000 pairs: main populations in Spain with 1192–1265 pairs, and Scotland with 425 pairs; sizeable populations (of 100 to 100s of pairs) in Norway, Sweden, Finland, France, Italy, Switzerland, Austria, Greece, former Yugoslavia, Bulgaria and European Russia. At least 100 pairs in Morocco and in Turkey; 21 pairs in Israel in 1984. A census in Spain in 2008 found 1553–1769 pairs#R and there were 53–61 pairs in Portugal in 2003–2004#R. From 1972–2008, population size and total productivity increased in study area in Italian Alps, even though the proportion of pairs that laid eggs declined substantially, suggesting that population was under density-dependent regulation#R. The Moroccan population has decreased considerably since the 1980s#R. In the small and isolated Ethiopian population, located in the Bale Mountains National Park, only three occupied territories were found in 2014 compared to seven during 1993–1997; the main negative factor appears to be the increasing human pressure#R. Little information about status in Asia: in Japan no more than 370–500 birds in 1980s. Various estimates of North American population, possibly with maximum of 70,000 birds in 1980s, with highest densities in in Wyoming, Colorado and Montana. Throughout much of range, historical causes of decline had diminished by late 20th century; limiting factors now are food supply and conservation of favourable habitat. Large numbers die due to accidents with powerlines, including electrocutions#R, and increasingly from collisions with wind turbines#R, but such mortality apparently not a significant factor in population trends.

    Recommended citation

    Orta, J., Kirwan, G.M., Boesman, P., Garcia, E.F.J. & Marks, J.S. (2020). Golden Eagle (Aquila chrysaetos). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53162 on 29 January 2020).