Eastern Imperial Eagle

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Common Name: Eastern Imperial Eagle
Scientific Name: Aquila heliaca

Size: 28-35 inches (72-90 cm); Wingspan: 70.8-85 inches (180-216 cm)

Habitat: Eurasia and Africa; it breeds in Austria, Azerbaijan, Bulgaria, China, Czech Republic, Macedonia, Georgia, Greece, Hungary, Kazakhstan, Russia, Serbia, Slovakia, Turkey and Ukraine. Breeding possibly also 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).

This is a lowland species that has been pushed to higher altitudes by persecution and habitat loss in Europe. In central and eastern Europe, it breeds in forests up to 1,000 m and also in steppe and agricultural areas with large trees, and nowadays also on electricity pylons. In the Caucasus, it occurs in steppe, lowland and riverine forests and semi-deserts. Eastern populations breed in natural steppe and agricultural habitats. Both adults and immatures of the eastern populations are migratory, wintering in the Middle East, East Africa south to Tanzania, the Arabian peninsula, the Indian Subcontinent and south and east Asia; wintering birds have also been reported in Hong Kong (China). These birds make their southward migration between September and November, returning between February and May. Wetlands are apparently preferred on the wintering grounds. Birds are usually seen singly or in pairs, with small groups sometimes forming on migration or at sources of food or water. In exceptional cases large groups of up to 200 have been known to form on autumn migration. Adults in central Europe, the Balkan peninsula, Turkey and the Caucasus are usually residents, whilst most immatures move south. Non-territorial birds often associate with other large eagles such as Aquila clanga and Haliaeetus albicilla on wintering and temporary settlement areas.

Status: Vulnerable. Global population: 3,500-15,000 adult individuals with a decreasing population trend. The European population comprises 1,800-2,200 pairs. There was a rapid decline in Europe and probably in Asia in the second half of the 20th century. Recently the central European population (177-192 pairs mostly in Hungary and Slovakia) appears to have been increasing as a result of conservation efforts, although the majority of the threats to the species persist. In the last six years, the occurrence of persecution incidents significantly increased, with more than 50 Eastern Imperial Eagles poisoned in Hungary. The Balkan population (76-132 pairs mostly in Bulgaria and Macedonia) 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 6,000 km2 study area, and a total population size of 50-150 pairs. This suggests that the Caucasian population may have been underestimated (it was previously assumed that less than 50 pairs bred in Azerbaijan and Georgia). Populations in the Volga Region of Russia are relatively stable, but are suspected to decline in the future due to the presence of threats at breeding sites. At least half of the world population (and possibly more) breeds in Russia (900-1,000 pairs and Kazakhstan (750-800 pairs). Although these populations currently seem to be stable, the Russian population has been predicted to decline in the next three to five years.

Breeding sites are threatened primarily by intensive forestry in the mountains, and by the shortage of large indigenous trees in the lowlands (e.g. illegal tree cutting affected several pairs in Russia and Bulgaria). Other threats are loss and alteration of feeding habitats, shortages of small and medium-sized prey species (particularly ground-squirrels Spermophilus spp.), human disturbance of breeding sites, nest robbing and illegal trade, shooting, poisoning and electrocution by powerlines. An average of 450 Eastern Imperial Eagles were killed by powerlines during the 2009 breeding season in the Altai region – 25% of the total population of the region. Habitat alterations associated with agricultural expansion threaten historical and potential breeding sites in former range countries. Hunting, poisoning, prey depletion and other mortality factors are also likely to pose threats along migration routes and in wintering areas. Competition for nest sites with Greater Spotted Eagles has been reported in the Altai region, Russia.

Diet: Mostly small mammals such as susliks (ground squirrels), marmots, gerbils, hamsters, and hares. Prey also include reptiles (including tortoises), insects, carrion; and birds (such as goose, ducks, crows, pigeons, game birds, and even flamingos).

Nesting: Adults are almost entirely brown. The crown and sides of the neck are light gold, and the shoulders have white patches. The tail is dark gray with a black subterminal band tipped with white, and the wing coverts also have white edges. The under tail is a pale rust to cream color. Eyes and feet are yellow and the beak is gray with a black tip. Their wings and tail are long, and the head is large, as are the feet.

Juveniles are light brown with dark brown streaks on the head, breast, scapulars, and wings. The wing coverts have white tips and the under parts are buff.

They mate for life, finding a partner at around age four. The breeding season is from February-July in Spain, and March-September in the rest of their range.

They build their nests out at the top of a tall tree, 10-20 m above the ground. A single pair may have several nests, which they use in rotation, repairing them when they need to. The nests are 1.2-1.5 m across and 60-70 cm deep, though they can grow to be 2.4 m or more across and 1.8 m deep. They weigh up to 100 kg and are lined with twigs, fur, grass, and debris, with fresh vegetation brought throughout the nest’s use. 1-4 eggs are laid and incubated for 43-52 days by both parents. Cainism is common, and the older and stronger chick will usually kill the younger. Fledging takes 63-77 days, but young will remain at the nest and be fed by the female until they can hunt on their own, around 160 days later.

Cool Facts: Aquila heliaca (Eastern Imperial Eagle) was formerly considered to include Aquila adalberti (Spanish Imperial Eagle) as a subspecies, but they are now considered different species by some authorities due to morphological, ecological, and molecular differences.

The monarchy of Austria-Hungary once chose the Imperial Eagle to be its heraldic animal.


Found in Songbird ReMix Birds of Prey Volume 5: Falcons, Hawks & Eagles

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