The Imperial Eagle (Aquila heliaca) is a species of day-flying bird of prey. Its body size reaches up to 84 cm with a wingspan between 180 cm to 215 cm. The adult birds are dark brown, almost black, with a very characteristic golden colour at the rear part of the head and neck. Usually, there are two white spots on the shoulders, of varying size, which may, in some individuals, be fully absent. The tail feathers are mainly yellowish-gray in colour (Ferguson-Lee et al. 2001; Porter 1981).
The juvenile birds have ochre brown feathers. The young birds' flight feathers are uniformly dark in colour.
Habitat and Ecology
The Imperial Eagle is found in grassland, woodland and forest ecosystems. It is a summer visitor to central, eastern and south-eastern Europe. It 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 (European Red List 2015).
Population and Distribution
The Imperial Eagle has a breeding population size of 190-250 pairs and a breeding range size of 30,200 square kilometres in the EU27. It is distributed in Central and Eastern Europe as well in Central Asia.
The breeding population trend in the EU27 is Increasing in the short term and Increasing in the long term. The EU population status of the Imperial Eagle was assessed as Near Threatened, because the species comes close to meeting the IUCN Red List criteria at the EU27 scale.
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 [Karyakin et al. 2009a] 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 c.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 (Karyakin et al. 2009b). 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 Eagle Aquila clanga has been reported in the Altai region, Russia (Karyakin et al. 2009c).
Ferguson-Lees, J.; Christie, D. (2001). Raptors of the World. Houghton Mifflin Harcourt. ISBN 0-618-12762-3.
Karyakin, I. V.; Nikolenko, E. G.; Bekmansurov, R. H. 2009a. Imperial Eagle in the Altai Mountains. Raptors Conservation: 66-79.
Karyakin, I. V.; Nikolenko, E. G.; Bekmansurov, R. H. 2009b. Results of monitoring of Greater Spotted Eagle and Imperial Eagle breeding grounds in the Altai pine forests in 2009, Russia. Raptor Research 17: 125-130.
Karyakin, I. V.; Nikolenko, E. G.; Vazhov, S. V.; Bekmansurov, R. H. 2009c. Raptor electrocution in the Altai region: results of surveys in 2009, Russia. Raptors Conservation 16: 45-64.
Porter, R. F. (1981). Flight identification of European raptors. A&C Black.