For the birdwatcher, there is no more magnificent sight than that of a golden eagle soaring in the sky, yet centuries of ignorance and persecution brought this bird close to extinction.
Golden eagles were once widely distributed throughout the mountainous regions of the British Isles, but over many years, their numbers have steadily dwindled. Now they are birds of the Scottish highlands and islands, with a few pairs nesting in the uplands of southwest Scotland.
The most reliable estimates put the size of our golden eagle population at 250 to 300 pairs. Their numbers were considered fairly stable, but recent evidence suggests they may decline slightly.
There are suitable tracts of the country where eagles are either scarce or absent altogether and other areas where breeding success is poor. On the other hand, some areas have thriving local populations.
Despite its lack of numbers, the golden eagle is the most widespread large eagle in the world. It is found in all the main mountainous areas of Europe, from arctic Norway and Russia down to Spain. It has outposts in North Africa and occurs across Asia, apart from the Indian sub-continent and southeast Asia. It is also found from Canada down to Mexico.
In all these areas, it is primarily a mountain eagle or a bird of wide, desolate upland plains, but in some areas, it also occurs on rocky sea cliffs, particularly in northwest Scotland and the Hebrides.
Adult golden eagles are mostly brown, although there is a lot of variation between individuals, with some birds looking quite dark while others are much paler. All adults have the rear crown and nape a pale straw-yellow hence its English name.
This feature may be difficult to see when out birdwatching, but on some birds, it can be apparent and, in sunlight, may appear almost white. Another feature most adults possess is paler feathering on the shoulders and wing coverts, where the wing joins the body.
An immature eagle is usually much darker than an adult and has characteristic white patches on its wings. The tail is white with a black band at the end. These white markings disappear as the bird matures and have virtually gone by the time it reaches the age of five, although breeding adults show traces of it for some time.
Golden Eagle or Common Buzzard?
In Great Britain, the bird most likely to be confused with a golden eagle is the common buzzard. You can tell the two species apart if the bird is not too far away. The golden eagle is much bigger than the buzzard.
If you cannot tell the difference in size, then it is best to compare the underparts. The buzzard has characteristic white and dark markings, whereas an adult golden eagle is a plain brown and a young brown with white patches.
If you cannot see the underparts, then the shape of both birds is an important aid in identification. The golden eagle has longer wings, with a much more prominent head and tail. When soaring, it holds its wings flatter, while buzzards hold their wings up to form a ‘V’ shape.
How Do Golden Eagles Hunt?
Golden eagles are superb fliers, able to hunt in the wildest terrain and all but the worst storms. They don’t rely on sheer speed or maneuverability when hunting. For these birds, it is a much more painstaking business.
The eagle flies low over the ground, patiently going back and forth, contouring along hillsides and across valleys until it locates its prey, then kills with a pounce or after a brief chase. The kill is achieved utilizing its powerful feet and huge curved talons. The bill may kill prey, but this is not its main purpose. The bill is used to rip and tear the flesh of its prey.
Golden eagles often hunt from a vantage point on a rock or some other lookout in the manner of many other birds of prey. It may even chase down and kill a flying bird, but this is rare. Even a grouse can outfly a golden eagle over a short distance. If the golden eagle does not have the height advantage in the sky, it can often lose its intended prey.
How Much Weight Can An Eagle Carry?
Eagles prefer carrying their food away rather than eating it at the scene of the kill. This does limit the size of the prey they attack. Golden eagles are extremely powerful birds, but the stories of them being able to carry a sheep are made up.
The smaller male can lift about 1.5 pounds, while the female can lift 3 pounds. Much depends on the lift they can get from the wind and whether the ground slopes so they can take off downhill. Normally. however, they can lift only as much as their weight, similar to the size of a large rabbit.
However, this still leaves the golden eagle with a wide prey choice. Scottish birds can kill almost all small to medium mammals or birds, from mice and sparrows to young deer.
Some more unusual kills include cats, dogs, fox cubs, squirrels, and geese. But most of the prey taken consists of just a few species, rabbits and hares, red grouse, and ptarmigan. Eagles also feed on carrion, sheep, and red deer in Britain. Carrion is an important food source in areas where prey is scarce.
When a golden eagle reaches the age of five, it is ready to find a mate and breed. The pair then establishes a hunting ground, usually about 20 square miles in Scotland, though sometimes it can be as large as 30 square miles. Golden eagles are not territorial about their hunting grounds, and territories often overlap.
Golden eagles pair for life and are largely sedentary, staying within their hunting grounds. Sometimes, however, an immature eagle may move in to replace a lost partner or occupy a hunting ground singly or with another immature eagle.
In late winter, with the approach of the breeding season, the male performs a courtship display. This consists of a spectacular rising and falling sky dance and is sometimes performed by the female.
Nest-building begins in March. An established pair usually has several nests and favorite sites on cliffs or crags not necessarily high up or inaccessible, and sometimes in trees. Each year the pair either picks one of their nests and repairs it for the coming season or establishes a new nest.
The nest is built with branches and heather stems and lined with finer vegetation. Two eggs are common, but sometimes one, or rarely three, are laid in late March or early April and are incubated for about six weeks, mainly by the female.
The young chicks exhibit a curious phenomenon known as the Cain and Abel battle, in which the elder of the two chicks kills the younger one, usually within the first three weeks of life. This battle occurs in 80% of nests where two eggs are laid.
The survivor stays in the nest for 10 to 11 weeks before fledging, after which it remains dependent on its parents for many weeks more.