Thursday, September 25, 2014

Golden eagle

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Golden eagle
1.
The golden eagle (Aquila chrysaetos) is one of the best-known birds of prey in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. These birds are dark brown, with lighter golden-brown plumage on their napes. Immature eagles of this species typically have white on the tail and often have white markings on the wings. Golden eagles use their agility and speed combined with powerful feet and massive, sharp talons to snatch up a variety of prey (mainly hares, rabbits, marmots and other ground squirrels).

Golden eagles maintain home ranges or territories that may be as large as 200 km2 (77 sq mi). They build large nests in high places (mainly cliffs) to which they may return for several breeding years. Most breeding activities take place in the spring; they are monogamous and may remain together for several years or possibly for life. Females lay up to four eggs, and then incubate them for six weeks. Typically, one or two young survive to fledge in about three months. These juvenile golden eagles usually attain full independence in the fall, after which they wander widely until establishing a territory for themselves in four to five years.

Once widespread across the Holarctic, it has disappeared from many areas which are now more heavily populated by humans. Despite being extirpated from or uncommon in some its former range, the species is still fairly ubiquitous, being present in sizeable stretches of Eurasia, North America, and parts of North Africa. It is the largest and least populous of the five species of true accipitrid to occur as a breeding species in both the Palearctic and the Nearctic.

For centuries, this species has been one of the most highly regarded birds used in falconry, with the Eurasian subspecies having been used to hunt and kill prey such as gray wolves (Canis lupus) in some native communities. Due to its hunting prowess, the golden eagle is regarded with great mystic reverence in some ancient, tribal cultures. The golden eagle is one of the most extensively studied species of raptor in the world in some parts of its range, such as the Western United States and the Western Palearctic.
2.
The Golden Eagle is one of the largest, fastest, nimblest raptors in North America. Lustrous gold feathers gleam on the back of its head and neck; a powerful beak and talons advertise its hunting prowess. You're most likely to see this eagle in western North America, soaring on steady wings or diving in pursuit of the jackrabbits and other small mammals that are its main prey. Sometimes seen attacking large mammals, or fighting off coyotes or bears in defense of its prey and young, the Golden Eagle has long inspired both reverence and fear.

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.

Color Pattern

  • Adult Golden Eagles are dark brown with a golden sheen on the back of the head and neck. For their first several years of life, young birds have neatly defined white patches at the base of the tail and in the wings.

Behavior

  • Usually found alone or in pairs, Golden Eagles typically soar or glide with wings lifted into a slight “V” and the wingtip feathers spread like fingers. They capture prey on or near the ground, locating it by soaring, flying low over the ground, or hunting from a perch.

Habitat

  • Golden Eagles favor partially or completely open country, especially around mountains, hills, and cliffs. They use a variety of habitats ranging from arctic to desert, including tundra, shrublands, grasslands, coniferous forests, farmland, and areas along rivers and streams. Found mostly in the western half of the U.S., they are rare in eastern states.

Cool Facts

  • Although capable of killing large prey such as cranes, wild ungulates, and domestic livestock, the Golden Eagle subsists primarily on rabbits, hares, ground squirrels, and prairie dogs.
  • The Rough-legged Hawk, the Ferruginous Hawk, and the Golden Eagle are the only American hawks to have legs feathered all the way to the toes.
  • The amount of white in the wings of a young Golden Eagle varies among individuals, and a few lack white in the wings entirely.
  • The Golden Eagle is the most common official national animal in the world—it's the emblem of Albania, Germany, Austria, Mexico, and Kazakhstan.
  • Because their common prey animals (mammals) don’t tend to ingest pesticides, Golden Eagles have escaped the harm sustained by fish-eating or bird-eating raptors from DDT and related chemicals. When these pesticides thinned the eggshells of many birds of prey, Golden Eagles’ shells retained normal thickness. Pesticide concentrations in their blood stayed below levels known to cause reproductive problems.
  • Biologists, engineers, and government officials have cooperated in developing and publicizing power-pole designs that reduce raptor electrocutions—caused when the large birds' wings or feet accidentally touch two lines and form a circuit. Since the early 1970s, utility companies have modified poles to prevent eagle electrocutions. And some new power lines in nonurban areas have been built to “raptor-safe” construction standards.
  • “Hacking,” an age-old falconry technique, is helping rebuild Golden Eagle populations. Humans feed caged, lab-reared nestlings at a nestlike hack site until the birds reach 12 weeks old, when the cage is opened and they begin feeding themselves. The fledglings continue to receive handouts from their hack-site caretakers for several weeks, until they gain full independence in the wild.
Golden Eagles live in open and semiopen country featuring native vegetation across most of the Northern Hemisphere. They avoid developed areas and uninterrupted stretches of forest. They are found primarily in mountains up to 12,000 feet, canyonlands, rimrock terrain, and riverside cliffs and bluffs. Golden Eagles nest on cliffs and steep escarpments in grassland, chapparal, shrubland, forest, and other vegetated areas.

Golden Eagles prey mainly on small to medium-sized mammals, including hares, rabbits, ground squirrels, prairie dogs, and marmots. Black-tailed jackrabbits are a key prey species throughout much of their range. These eagles are also capable of taking larger bird and mammal prey, including cranes, swans, deer, and domestic livestock. They have even been observed killing seals, mountain goats, bighorn sheep, pronghorn, coyotes, badgers, and bobcats. In addition to live prey, Golden Eagles often feed on carrion, following crows and other scavengers to a meal. They also catch fish, rob nests, and steal food from other birds.

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