Imperial eagle (Aquila heliaca)
|Also known as:||Asian imperial eagle, Eastern imperial eagle|
|Spanish:||Aguila Imperial, Aguila Imperial Oriental|
|Size||Length: 92 cm (2)|
Wingspan: 214 cm (2)
|Weight||3 kg (2)|
- Male and female imperial eagles form pairs at around 4 years of age, and remain in this monogamous pair for life
- The Imperial eagle's large nest is called an eyrie, and is constructed from sticks at the top of a tall tree
- The smallest imperial eagle hatchling is normally pecked to death or outcompeted for food by its older sibling
- Originally a lowland species, in some areas the imperial eagle has been pushed to higher elevations by habitat loss and hunting
- In 2009, the imperial eagle was found to be breeding in Austria after being extinct in the region for nearly 200 years
The imperial eagle is 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).
Adult imperial eagles (Aquila heliaca) 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).
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).
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).
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).
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).
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).
For further information on the imperial eagle and other bird species:
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- Carrion: dead flesh.
- Incubate: to keep eggs warm so that development is possible.
- Monogamous: having only one mate during a breeding season, or throughout the breeding life of a pair.
- Steppe: a biome (or subdivision of the Earth’s surface) that is composed of a swathe of temperate grassland stretching from Romania to China.
IUCN Red List (May, 2009)
Animal Diversity Web (February, 2005)
CITES (May, 2009)
Global Register of Migratory Species (April, 2008)
BirdLife International (February, 2005)
- BirdLife International. (2001) Threatened Birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, UK.