Male and female imperial eagles form monogamous pairs at around four years old and then stay together for life. They build a large nest, known as an eyrie, from sticks, at the top of a tall tree (2), and will return to this and a couple of other nests in rotation every year, making repairs as necessary (6). During the spring, the female lays between two and four eggs, which are incubated for 43 days by both parents, hatching from the end of May to the middle of June. The smallest hatchling is usually pecked or starved to death by its older, stronger sibling, which claims more of the adults' attention. The surviving nestling will learn to fly at around two months, but will stay at the nest for another few weeks, being fed by the female until it can hunt (2). The imperial eagle usually hunts alone, targeting small mammals (mainly ground squirrels known as susliks (Spermophilus citellus)), reptiles, birds and carrion (2). They have excellent eyesight for spotting prey whilst gliding, but they may also steal the catch of other birds of prey, sometimes obtaining the majority of their food this way (6). Whilst each bird begins its migratory journey alone, imperial eagles often congregate into loose flocks of ten or more to soar on level wings, covering up to 8,000 kilometres in six weeks (2).

Adult imperial eagles are stocky in shape with black-brown feathers and a pale golden crown and nape. The shoulders have prominent white patches and the tail is greyish-brown. The head is large, the wings are long and straight and the strong feet have long, curved talons. Juveniles are paler with patterning on the rump, wings and tail. They have bold streaks on the underwings and the underside of the body (2).

C Europe to Mongolia; winters to Africa, n India and China.

Aquila heliaca breeds in Austria, Azerbaijan, Bulgaria, China, Czech Republic, Macedonia, Georgia, Greece, Hungary, Kazakhstan, Russia, Serbia, Slovakia, Turkey and Ukraine. Breeding has not been proved but possibly occurs in Afghanistan, Albania, Armenia, Bosnia and Herzegovina, Croatia, Iran, Kyrgyzstan, Moldova, Mongolia, Pakistan, Romania, Tajikistan, Turkmenistan and Uzbekistan. On passage and in winter, birds are found in the Middle East, east Africa south to Tanzania, the Arabian peninsula, the Indian subcontinent and south and east Asia (from Thailand to Korea). The population is probably only a few thousand pairs, with a total population of 1,110-1,624⁹ pairs estimated in Europe. There was a rapid decline in Europe and probably in Asia in the second half of the 20^th century. Recently the Central European population (121-134 pairs mostly in Hungary and Slovakia) has been increasing ⁹, while the Balkan population (81-126 pairs mostly in Bulgaria and Macedonia¹⁰) is apparently stable (although the last proven breeding in Greece took place in 1993). Recent surveys in Azerbaijan found relatively high densities in the north-western plains, estimating 50-60 pairs within a 6000 km² study area¹¹. This suggests that the Caucasian population may have been underestimated (it was previously assumed that less than 50 pairs bred in Azerbaijan and Georgia¹¹. The majority of the world population breeds in Russia (total 900-1000 pairs⁷) and Kazakhstan (750-800 pairs²). Although these populations currently seem to be stable, the Russian population has been predicted to decline in the next three to five years³.

Aquilua heliaca can be found throughout southern Europe, from Greece to southern Russia. Here it can be found as far south as a line drawn from Cyprus to northwest India, and as far east as Central Siberia. It can also be found sparsely in Spain. In winter it migrates to northeast Africa (from Egypt to Kenya), India, and southeast China (Channing 2000).

Biogeographic Regions: palearctic (Native ); oriental (Native ); ethiopian (Native )

The imperial eagle is found from southern Europe to southern Russia, as well as northwest India and central Siberia. In winter it migrates to the Middle East, east Africa as far south as Tanzania, the Arabian Peninsula, the Indian subcontinent and south and east Asia (2).

The Imperial Eagle is the second largest eagle to reside in Europe. It can grow to a length of about 0.92 meters. It can have a wingspan approaching 2.14 meters and have a mass of about 3.6 kilograms. Adults are black-brown in color. They have a pale golden crown and nape, and a grey base that extends to the tail. They also have very apparent white "braces" on their scapulars. Juveniles are paler and more variegated than the adults. They are yellow-brown with rump, wing, and tail patterns similar to the patterns of the Lesser Spotted, pale Spotted, Tawny and Steppe eagles. They are distinguished from these eagles, however, by the bolder streaks on their under-wings and body, the lack of a pale band under the wing-coverts, and their larger and more majestic build. Both the juveniles and adults have noticeably protruding head and long, parallel-edged wings. Like other eagles, they have strong legs and feet. Their feet include long, curved talons that they use to seize, kill and carry their prey. They also have large eyes that are located slightly to the side of the head. These eyes provide them with extremely keen eyesight, allowing them to spot prey from high in the air. (Peterson 1993, Wyss 1997, Eagle 1988)

Average mass: 3000 g.

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

The Imperial Eagle tends to live in forests, where it will build a huge, conspicuous nest in an isolated tall tree. Old forests, and the forests in mountains, hills, and along rivers are all common habitats. It has, however, also been known to live in steppes, open landscapes, agricultural areas, and even semideserts. Imperial eagles hunt in open fields or wetlands. During migration, a variety of habitats are used, though they seem to prefer to winter in wetlands. (Heredia 1996, Peterson 1993)

Terrestrial Biomes: savanna or grassland ; forest

Originally a lowland species, the imperial eagle has been pushed to higher elevations by habitat loss and hunting. In central and eastern Europe it is found in forests up to 1,000 metres, as well as steppe and agricultural areas with large trees. In the Caucasus, it is still found in lowland and riverine forests and semi-deserts. It winters in wetlands (5).

The Imperial Eagle, like other birds of prey, is a carnivore. Its main source of food is small mammals, such as rabbits and susliks (ground squirrels in the genus Spermophilus). It will also eat reptiles, including some poisonous snakes, and other birds, such as young magpies, waders, and ducks. It has been known to feed on some carrion as well, carrying off lambs that were already dead. It generally hunts by slowly flying around the open areas near the forest where it resides, staying just above the treetop level, and scanning for prey. Its excellent eyesight makes spotting prey easy. When it sees a suitable prey item it will drop down on it, using its talons to kill and carry the prey. It will also, on a few occasions, perch high on a tree near the edge of the forest, and drop on its prey from there. (Channing 2000, Eagle 1988)

Aquila heliaca preys on:
Marmota bobak

This list may not be complete but is based on published studies.

Range lifespan

Status: wild: 56 (high) years.

Average lifespan

Status: captivity: 56 years.

Maximum longevity: 56 years (captivity)

Imperial Eagles are ready to breed for the first time when they are about four years old. When they reach this age, they find a mate whom they stay with for life. If one happens to die, however, the other will usually find a new mate and breed the next year. Every pair will build a nest, called an eyrie, in the top of a tree. These nests are generally made mainly with sticks, and are used only during the spring and summer months. Females will generally lay two eggs a year. Sometimes, however, they will lay three eggs, and on a few rare occasions they will lay four. These eggs have to be incubated for about forty-three days before they can hatch, and both parents will participate in the incubation. Even though two eggs are usually hatched, it is unusual for both eaglets, or baby eagles, to survive. One is usually born a couple days earlier than the other. This older, larger eaglet eats more than its share of food, and will repeatedly attack, often killing, the younger one. The young eagles are ready to fly when they are sixty days old. They stay near the nest, however, for an additional two weeks, and continue to be fed by the mother until they are ready to hunt for themselves. (Bologna 1978, Eagle 1988)

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2007
  Vulnerable
• 2004
  Vulnerable
• 2000
  Vulnerable
• 1996
  Vulnerable
• 1994
  Vulnerable

The Imperial Eagle is classified as endangered at the European level, and vulnerable at the global level. There are several threats to its survival, and habitat alterations are probably the most critical. Several kinds of forestry operations in their breeding areas can seriously hurt its ability to survive and reproduce. These operations include, but aren't limited to, the cutting of forests for reafforestation with alien species, cutting of large, old trees in forests and along forest edges, and logging disturbances. Several other types of human disturbances can also be major limiting factors. The Imperial Eagle is a very sensitive species, and can easily be hurt by both intentional and unintentional interference. An example of intentional interference is hunting. Imperial Eagles are often shot during migrations. Examples of unintentional interference include the eagles ingesting poisons meant to control other species and flying into power lines, electrocuting themselves. (Heredia 1996)

US Federal List: no special status

CITES: appendix i

IUCN Red List of Threatened Species: vulnerable

Regular passage visitor and winter visitor?

Classified as Vulnerable (VU) on the IUCN Red List (1), and listed on Appendix I of CITES (3) and Appendices I and II of the Convention on Migratory Species (CMS or Bonn Convention) (4).

Population

Population Trend

Major Threats

Native forest has been lost to the forestry industry as trees are felled and replaced with introduced species, depriving the imperial eagle of nesting and feeding sites. Nest robbing by humans is common, and trade in this species remains a problem. Additionally, imperial eagles are shot and poisoned, and are electrocuted on power lines. Shortages of prey species, particularly the suslik (Spermophilus citellus), have also contributed to the decline of this eagle (4).

Conservation Actions

The imperial eagle is legally protected in Azerbaijan, Bulgaria, Croatia, Georgia, Greece, Hungary, Romania, Slovakia, Turkey and Ukraine. The Eastern Imperial Eagle Working Group was established in 1990 and the European Action Plan was published in 1996. Crucial steps in the conservation of this eagle are the improvement of forestry practices, the maintenance of large trees and the prevention of mortality via nest robbing, illegal trade, poisoning and power lines (6).

Although rare, Imperial Eagles have been known to attack humans who come too close to their nests. They may dive at a person who gets too close and strike at them with their talons. (Eagle 1988)

Imperial Eagles are beneficial to farmers and ranchers because they feed on rabbits and other small mammals. By eating these animals, the Imperial Eagle reduces their numbers, and thus reduces the damage they can do. This eagle also feeds on venomous reptiles, many of which have been known to cause serious harm to humans. (Channing 2000)