Golden Eagle

The golden eagle is a very large raptor, measuring 66 to 102 centimeters from bill to tail, with a wingspan of 1.8 to 2.34 meters, the fifth largest of any living eagle. Females are clearly bigger than males. In Europe, males weigh about 2.8 to 4.6 kilograms and females 3.8 to 6.7, and the heaviest wild golden eagle on record, a female caught in Wyoming in 2006, weighed about 7.7 kilograms. The largest birds are the Himalayan and Central Asian golden eagles, known as berkut, while those of Japan and Korea are smaller and darker. So what does a golden eagle look like? Adults are mostly dark brown, with grey on the inner wing and tail and a pale golden crown and nape. The legs are feathered all the way to the toes, and the feet and the base of the bill are yellow. In flight the wings are long and broad, often held in a shallow V, and the tail is fairly long. Young birds are darker, with white patches at the base of the flight feathers and a white tail with a dark band at the tip. These white marks shrink year after year, and full adult plumage only comes at five to six years of age.

Few birds match the golden eagle's reach. It breeds across an enormous band of the Northern Hemisphere: in North America from Alaska and northern Canada through the western United States to central Mexico, in Europe from Scotland, Scandinavia and the Iberian Peninsula to the Alps, the Carpathians and the Balkans, and across Asia from Turkey and the Caucasus to Central Asia, the Himalayas, Mongolia, China, Korea and Japan. In Africa it lives in the Atlas Mountains and other rocky ranges of the north and the Sahara, and an isolated population survives far to the south in Ethiopia's Bale Mountains. It also nests in the mountains of Arabia, from Oman to Yemen. Within this range it favors open, rugged country: mountains, high plateaus, moorlands, steppe, desert hills and the edge of the tundra, where the sky is wide and the terrain offers good hunting. It generally avoids dense forest and flat, intensively farmed land, and it no longer breeds in the eastern United States. Most populations stay in their territory all year, but eagles from northern Canada, Alaska and Siberia migrate south for the winter.

Rabbits and hares form the backbone of the golden eagle's diet across much of its range, but this bird is a remarkably flexible hunter. Ground squirrels, marmots, prairie dogs, pikas and susliks are taken regularly depending on what the local landscape offers, along with gamebirds such as grouse, ptarmigan and partridges. Where larger prey is available, golden eagles attack foxes, young deer, chamois kids, mountain goats and reindeer calves, and in rare cases they have killed adult deer and even wolves. In Central Asia, trained eagles are used to hunt foxes and wolves. Tortoises are taken in the Mediterranean, and the eagles have been seen dropping them from the air to break the shell. Carrion becomes important in winter, when live prey is harder to find. The eagle hunts mainly by soaring or contour flying low along slopes, using the terrain to surprise its prey, and then strikes with its powerful feet. In a full dive it can reach 240 to 320 kilometers per hour, as fast as a stooping peregrine falcon. Pairs sometimes hunt together, one driving the prey toward the other.

Spending hours aloft without apparent effort is one of the golden eagle's defining traits. It uses rising warm air and the updrafts along ridges to cover enormous stretches of ground, cruising at around 45 to 52 km/h, and it can glide at up to 190 km/h when hunting or displaying. Golden eagles hold some of the largest home ranges of any bird, and pairs defend them fiercely against rivals, other raptors and even ravens. In courtship and territorial displays they climb high and then plunge in a series of steep undulating dives. Outside the breeding season they are usually solitary and quiet, although in very cold weather they may perch close together: in eastern Idaho, 124 golden eagles were once seen perched along a line of 85 power poles on a freezing night. Their calls are surprisingly weak whistles and yelps for such a large bird. Their eyesight is exceptional, several times sharper than ours, which lets them spot a moving hare from far away. Some flights between pairs or by single birds seem to be pure play, with eagles dropping and catching sticks in the air.

Golden eagles are monogamous and pairs may stay together for several years or for life. Courtship starts in late winter with dramatic undulating flights over the territory. Nests, called eyries, are built on sheltered cliff ledges or in the crowns of tall trees, and in some places on power pylons. The same nest may be added to and reused for decades, and many pairs keep two or more nests in their territory and switch between them. Eggs are laid between late January and early April depending on latitude. The female lays up to four eggs, usually two, and incubates them for about six weeks. The first chick hatches a few days before the second and is bigger and stronger, and in many nests it attacks its younger sibling, which often dies, a behavior known as Cainism. Typically one or two young survive and fly at about three months old. They become independent in autumn and then wander widely for four or five years before settling in a territory of their own.

Few birds have such a long history with people. The golden eagle is the eagle on the coat of arms of Mexico, perched on a cactus and eating a snake, the image from the Aztec legend of the founding of Tenochtitlan, and it appears at the center of the Mexican flag. Many eagles on old European coats of arms, from the Roman legions onward, were inspired by large eagles like it. For centuries the golden eagle has been one of the most prized birds in falconry. In Central Asia, Kazakh eagle hunters, known as berkutchi, still train female golden eagles to hunt foxes, hares and even wolves on horseback, a tradition kept alive especially in the Bayan Ölgii province of western Mongolia and in Kazakhstan, where eagle festivals draw visitors from around the world. Its scientific name, Aquila chrysaetos, comes from Latin and Greek and simply means golden eagle. In Spanish it is called águila real, the royal eagle, and in French aigle royal.

The IUCN classifies the golden eagle as Least Concern. The world population is estimated at 170,000 to 250,000 birds, with 60,000 to 100,000 breeding pairs, making it one of the most numerous large eagles. Even so, it has declined sharply or disappeared in many areas, including Ireland, most of England and the eastern United States, where the last known pair nested in Maine until 1999. Illegal shooting and poisoning, often linked to the protection of livestock or of grouse moors, continue to kill eagles in Europe and the Middle East. Collisions with wind turbines and power lines are a growing problem: the Altamont Pass wind farms in California became known for killing many golden eagles. Lead poisoning from bullet fragments in carcasses and gut piles affects birds across North America and Europe. Disturbance near nests can make pairs abandon eggs or chicks. Protection has helped in many countries: Scotland had 508 pairs in its 2015 national survey, and young eagles from the Highlands have been moved to the south of Scotland since 2018 to rebuild the population there.