The Imperial Eagle
Description

Aquila heliaca Savigny 1809, Upper Egypt.
Monotypic, currently no subspecies distinguished (formerly some authors distinguished   A. h. ricketti in the Eastern parts of the species' range, and for a long time Aquila adalberti was considered to be the subspecies of A. heliaca ) (Del Hoyo et. al. 1994) . Length 72-84 cm, wingspan 180-215 cm, weight 2450-4530 g. Adults are dark brown - almost black - in their body, with the back of head and neck golden. Normally it has two white shoulder patches of variable size, which may lack completely in some individuals.

The ground colour of the tail feathers is yellowish-grey with darker, fine cross-barring and a dark terminal band. Body feathers of juveniles are brown with ochre centres causing a generally light-brownish appearance of young birds. The flight feathers of juveniles are uniformly dark with light trailing edges. Adult plumage is reached in 4-6 years. Birds in transitional plumages show a variable plumage formed by a mixture of darker and lighter body feathers. The imperial eagle is a priority species in a number of international conventions. In Hungary it is strictly protected with an assigned theoretical natural value of 1 Million HUF (~4000 EUR).
Distribution
The distribution range of the species stretches from Central and South-Eastern Europe to Central Asia (see map). Westward from Hungary and Slovakia it is represented by only few pairs in the Czech Republic and Eastern Austria. By the mid-20 th century the Hungarian population had suffered a drastic decline due to the persecution of birds of prey.   Today's population exceeds 60 breeding pairs. The population is increasing by one to three pairs each year, which is a remarkable phenomenon, since throughout most of the species' range populations are in decline. The Asian breeding population moves for the winter months to South-East Asia, Northern India and the Middle-East, adults of the Carpathian basin do not migrate.
Breeding



The imperial eagle breeds both in mountains and agricultural lowland areas. Breeding pairs spend the winter months in or near the breeding areas, while most juveniles wander around. A large part of the Hungarian population breeds in the North-Eastern mountain range and the surrounding lowlands. Most nests are built in the top of tree canopies, the interior of the nests is usually furnished with thin sticks and leaves. The birds can build their nest on any tree species if they find appropriate branches to hold the nest sufficiently high above the ground. Nests that have been used for many years or decades can be of considerable size, their diameter reaching 1.5 m and weight over 100 kg. Pairs can start nest construction at the end of January - beginning of February (depending on weather). Egg-laying occurs usually at the beginning of April, and both birds participate in the incubation. Chicks hatch after 43 days of incubation and spend 57-65 days in the nest. For many weeks after fledging they depend on their parents.
Feeding
The favourite prey of the imperial eagle are daytime-active small to medium size mammals such as the suslik ( Spermophilus citellus ) and the hamster ( Cricetus cricetus ). However, there have been changes in the food composition of the eagles due to the drastic decline in suslik populations observed in the last decade in Hungary. Hamsters are locally important prey animals, but generally the most important prey species nowadays are hares ( Lepus europeus ) and medium-size birds (rooks, crows, magpies, pheasants). Hedgehogs are frequently taken, too. The imperial eagle also feeds occasionally on carrion, mostly during winter or on migration, though in some areas (e.g. Balkans) also during the breeding period. In Hungary carrion eating is mostly characteristic of young birds.
References:
del Hoyo, J., Elliott, A. & Sargatal, J. eds. (1994). Handbook of the Birds of the World. Vol. 2. New World Vultures to Guineafowl, pp. 194-195. Lynx Edicions, Barcelona
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