Golden Eagle
The Golden Eagle is a very large raptor, 26 to 40 inches in length and with a wingspan of 5 ft 11 inches to 7 ft 8 inches. The wingspan is the fifth largest among living eagle species. Females are larger than males with a bigger difference in larger sub-species. In the species overall, males average around 7.9 pounds and females around 11 pounds. The maximum size of the Golden Eagle is debated. Large sub-species are the heaviest and the species is on average the seventh heaviest living eagle species. The Golden Eagle is the second heaviest breeding eagle in north America, Europe and Africa and the fourth heaviest in Asia.
Adults of both sexes have similar plumage and are primarily dark brown with some grey on the inner wing and tail and a paler, typically golden, colour on the back of the crown and nape that gives the species its common name. Unlike other eagle species, where the tarsal feathers are typically similar in colour to the rest of the plumage, the tarsal feathers of the Golden Eagle tend to be paler and range from light golden to white. In addition, some full-grown birds have white "epaulettes". The bill is dark at the tip, fading to a lighter horn colour, with a yellow cere. The bare portion of the feet is yellow.
Juveniles are similar to adults but tend to be darker and can appear black on the back. About two thirds of their tail length is white, ending with a broad, black band. Compared to the relatively consistently white tail, the white patches on the wings are extremely variable. Juveniles of less than 12 months of age tend to have the most white in their plumage and this is gradually replaced by a characteristic rusty brown colour. Due to the variability between individuals, juveniles cannot be reliably aged by sight alone. The final adult plumage is not fully attained until the birds are between 5.5 and 6.5 years old.
The Golden Eagle is sometimes considered to be the best flyer among eagles and perhaps amongst all raptors. It is equipped with broad, long wings with finger-like indentations on the tips of the wings. It is unique amongst the eagle species in that it often flies with the wings held in a slight, upturned V-shape. When it needs to flap, the Golden Eagle appears at its most laboured but flapping is less common than soaring or gliding. Flapping flight usually consists of 6 to 8 deep wing-beats interspersed with 2 to 3 second glides. While soaring, the wings and tail are held in one plane with the primary tips often spread. A typical, unhurried soaring speed is around 28 to 32 mph.
When hunting or displaying, the Golden Eagle can glide very fast, reaching speeds of up to 120 mph. When stooping (diving) in the direction of prey or during territorial displays, it holds its legs up against its tail and holds its wings tight and partially closed against its body. When diving after prey, it can reach 150 to 200 mph. Although less agile and manoeuvrable, the Golden Eagle is apparently equal to and possibly even the superior of the Peregrine Falcon’s stooping and gliding speeds. This makes the Golden Eagle one of the fastest living animals.
Size readily distinguishes the Golden Eagle from most other raptors when it is seen well. Most other raptors are considerably smaller. Among raptors that share the Golden Eagle's range, only some Old World vultures and the California Condor are distinctly larger with longer, broader wings which are typically held more evenly in a slower, less forceful flight. These birds also have dramatically different colour patterns. Distinguishing the Golden Eagle from other eagle species in Eurasia is more difficult. Identification may rely on the Golden Eagle's relatively long tail and patterns of white or grey on the wings and tail. Unlike the Golden Eagle, other eagles do not generally fly with the wings held in a slight, upturned V-shape. At close range, the golden to rufous nape of the Golden Eagle is distinctive and most other eagles have darker plumage. Among Eurasian eagles, the adult Eastern Imperial Eagle and the Spanish Imperial Eagle come closest to reaching the size of the Golden Eagle but both are distinguished by their longer necks, flatter wings in flight, white markings on their shoulder forewing-coverts, paler cream-straw coloured nape patch and generally darker colouration. The Steppe Eagle can also approach the Golden Eagle in size but it is more compact and smaller headed with little colour variation to the dark earth-brown plumage
The nominate sub-species, Aquila chrysaetos chrysaetos or European Golden Eagle, is found throughout most of Europe. In the UK, there are estimated to be 400 to 500 breeding pairs which can be found in the wild, open moorlands and mountains of Scotland, in particular the Scottish Highlands. The Golden Eagle is also found in European Russia, reportedly reaching an eastern limit around the Yenisei River, and further south at a similar longitude into west Kazakhstan and north Iran.
At one time, the Golden Eagle was found in a great majority of temperate Europe, north Asia, north America, north Africa and Japan. Although widespread and quite secure in some areas, in many parts of the range the Golden Eagle has experienced a sharp population decline and it has become extinct in some areas. The total number of individuals is estimated to range somewhere between 170,000 and 250,000 whilst the estimated total number of breeding pairs ranges from 60,000 to 100,000. It has the largest known range of any member of its family with a range estimated at about 55 million square miles and it is the second most wide ranging species after the Osprey. On a global scale, the Golden Eagle is not considered threatened by the IUCN.
The Golden Eagle is fairly adaptable in its habitat requirements but it often found in areas with a few shared ecological characteristics. It is best suited to hunting in open or semi-open areas and native vegetation seems to be attractive to it. It typically avoids developed areas of any type from urban to agricultural as well as heavily forested regions. The largest numbers are found in mountainous regions although it is not solely tied to high elevations and it can breed in lowlands if the local habitats are suitable.
The majority of Golden Eagle populations are sedentary but it is also a partial migrant in the north of its range. Whilst it is a very hardy species and well adapted to cold climates, it can not tolerate declining food sources and birds which breed at latitudes greater than 60°N are usually migratory and a short migration may also be undertaken by birds which breed at about 50°N.
The Golden Eagle usually mates for life although if one of the pair dies, the survivor will readily accept a new mate. Adults occupy a hunting and nesting area all year and they can be seen soaring and advertising their ownership of their home range at any time. However, their spectacular undulating display flight is most often seen from February to May. Each home range contains several night roosts and often a choice of 2 or 3 alternative nest sites (eyries) usually on cliff ledges. Both adults build the nest which is a substantial structure of branches, twigs and heather and lined with grasses and decorated with green foliage. The eyries are traditional and can be used for many years by the same or successive birds. The eyrie is added to each year it is used and it can end up quite a remarkable size. Cliff nests are 3 to 5 feet across and up to 6.5 feet high whilst tree nests can be twice this size.
The female generally lays 2 eggs 3 to 4 days apart in March and incubates them for 43 to 45 days. Incubation starts with the first egg and the chicks hatch a few days apart. The first chick to hatch is dominant over the younger one which has only a 20% chance of surviving the crucial first weeks. The female does most of the brooding and feeding of the young whilst the male provides the female and the young with all the food, especially during the early stages. The female broods the chicks almost continuously for the first 2 weeks. After this, she will regularly leave the nest and share the hunting with the male. The young will fledge when they are 65 to 70 days old and will become independent after a further 90 to 100 days. Juveniles occasionally stay with their parents until November or December but are usually driven away by October. The young birds will breed for the first time at 3 to 4 years of age.
The average life span of a Golden Eagle is around 14 years although it is thought that 75% of young birds die before reaching maturity. The oldest known Golden Eagle reached an age of 32 years. Natural sources of mortality are largely reported anecdotally.
Date: 4th November 2008
Location: Bruichladdich to Port Charlotte, Islay, Argyll
Adults of both sexes have similar plumage and are primarily dark brown with some grey on the inner wing and tail and a paler, typically golden, colour on the back of the crown and nape that gives the species its common name. Unlike other eagle species, where the tarsal feathers are typically similar in colour to the rest of the plumage, the tarsal feathers of the Golden Eagle tend to be paler and range from light golden to white. In addition, some full-grown birds have white "epaulettes". The bill is dark at the tip, fading to a lighter horn colour, with a yellow cere. The bare portion of the feet is yellow.
Juveniles are similar to adults but tend to be darker and can appear black on the back. About two thirds of their tail length is white, ending with a broad, black band. Compared to the relatively consistently white tail, the white patches on the wings are extremely variable. Juveniles of less than 12 months of age tend to have the most white in their plumage and this is gradually replaced by a characteristic rusty brown colour. Due to the variability between individuals, juveniles cannot be reliably aged by sight alone. The final adult plumage is not fully attained until the birds are between 5.5 and 6.5 years old.
The Golden Eagle is sometimes considered to be the best flyer among eagles and perhaps amongst all raptors. It is equipped with broad, long wings with finger-like indentations on the tips of the wings. It is unique amongst the eagle species in that it often flies with the wings held in a slight, upturned V-shape. When it needs to flap, the Golden Eagle appears at its most laboured but flapping is less common than soaring or gliding. Flapping flight usually consists of 6 to 8 deep wing-beats interspersed with 2 to 3 second glides. While soaring, the wings and tail are held in one plane with the primary tips often spread. A typical, unhurried soaring speed is around 28 to 32 mph.
When hunting or displaying, the Golden Eagle can glide very fast, reaching speeds of up to 120 mph. When stooping (diving) in the direction of prey or during territorial displays, it holds its legs up against its tail and holds its wings tight and partially closed against its body. When diving after prey, it can reach 150 to 200 mph. Although less agile and manoeuvrable, the Golden Eagle is apparently equal to and possibly even the superior of the Peregrine Falcon’s stooping and gliding speeds. This makes the Golden Eagle one of the fastest living animals.
Size readily distinguishes the Golden Eagle from most other raptors when it is seen well. Most other raptors are considerably smaller. Among raptors that share the Golden Eagle's range, only some Old World vultures and the California Condor are distinctly larger with longer, broader wings which are typically held more evenly in a slower, less forceful flight. These birds also have dramatically different colour patterns. Distinguishing the Golden Eagle from other eagle species in Eurasia is more difficult. Identification may rely on the Golden Eagle's relatively long tail and patterns of white or grey on the wings and tail. Unlike the Golden Eagle, other eagles do not generally fly with the wings held in a slight, upturned V-shape. At close range, the golden to rufous nape of the Golden Eagle is distinctive and most other eagles have darker plumage. Among Eurasian eagles, the adult Eastern Imperial Eagle and the Spanish Imperial Eagle come closest to reaching the size of the Golden Eagle but both are distinguished by their longer necks, flatter wings in flight, white markings on their shoulder forewing-coverts, paler cream-straw coloured nape patch and generally darker colouration. The Steppe Eagle can also approach the Golden Eagle in size but it is more compact and smaller headed with little colour variation to the dark earth-brown plumage
The nominate sub-species, Aquila chrysaetos chrysaetos or European Golden Eagle, is found throughout most of Europe. In the UK, there are estimated to be 400 to 500 breeding pairs which can be found in the wild, open moorlands and mountains of Scotland, in particular the Scottish Highlands. The Golden Eagle is also found in European Russia, reportedly reaching an eastern limit around the Yenisei River, and further south at a similar longitude into west Kazakhstan and north Iran.
At one time, the Golden Eagle was found in a great majority of temperate Europe, north Asia, north America, north Africa and Japan. Although widespread and quite secure in some areas, in many parts of the range the Golden Eagle has experienced a sharp population decline and it has become extinct in some areas. The total number of individuals is estimated to range somewhere between 170,000 and 250,000 whilst the estimated total number of breeding pairs ranges from 60,000 to 100,000. It has the largest known range of any member of its family with a range estimated at about 55 million square miles and it is the second most wide ranging species after the Osprey. On a global scale, the Golden Eagle is not considered threatened by the IUCN.
The Golden Eagle is fairly adaptable in its habitat requirements but it often found in areas with a few shared ecological characteristics. It is best suited to hunting in open or semi-open areas and native vegetation seems to be attractive to it. It typically avoids developed areas of any type from urban to agricultural as well as heavily forested regions. The largest numbers are found in mountainous regions although it is not solely tied to high elevations and it can breed in lowlands if the local habitats are suitable.
The majority of Golden Eagle populations are sedentary but it is also a partial migrant in the north of its range. Whilst it is a very hardy species and well adapted to cold climates, it can not tolerate declining food sources and birds which breed at latitudes greater than 60°N are usually migratory and a short migration may also be undertaken by birds which breed at about 50°N.
The Golden Eagle usually mates for life although if one of the pair dies, the survivor will readily accept a new mate. Adults occupy a hunting and nesting area all year and they can be seen soaring and advertising their ownership of their home range at any time. However, their spectacular undulating display flight is most often seen from February to May. Each home range contains several night roosts and often a choice of 2 or 3 alternative nest sites (eyries) usually on cliff ledges. Both adults build the nest which is a substantial structure of branches, twigs and heather and lined with grasses and decorated with green foliage. The eyries are traditional and can be used for many years by the same or successive birds. The eyrie is added to each year it is used and it can end up quite a remarkable size. Cliff nests are 3 to 5 feet across and up to 6.5 feet high whilst tree nests can be twice this size.
The female generally lays 2 eggs 3 to 4 days apart in March and incubates them for 43 to 45 days. Incubation starts with the first egg and the chicks hatch a few days apart. The first chick to hatch is dominant over the younger one which has only a 20% chance of surviving the crucial first weeks. The female does most of the brooding and feeding of the young whilst the male provides the female and the young with all the food, especially during the early stages. The female broods the chicks almost continuously for the first 2 weeks. After this, she will regularly leave the nest and share the hunting with the male. The young will fledge when they are 65 to 70 days old and will become independent after a further 90 to 100 days. Juveniles occasionally stay with their parents until November or December but are usually driven away by October. The young birds will breed for the first time at 3 to 4 years of age.
The average life span of a Golden Eagle is around 14 years although it is thought that 75% of young birds die before reaching maturity. The oldest known Golden Eagle reached an age of 32 years. Natural sources of mortality are largely reported anecdotally.
Date: 4th November 2008
Location: Bruichladdich to Port Charlotte, Islay, Argyll
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Also in: Birds of prey
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