Imperial Eagle
Aquila heliaca Savigny, 1809
Aquila imperialis Beschtein, 1812: Finsch, 1859: 380; Radakoff, 1879: 165; Hristovich, 1890: 187; Reiser, 1894: 116; Klain, 1909: 77; Aquila melaneotus (L.): Reiser, 1894: 116.
Order Falconiformes
Family Accipitridae
Conservation status: in Bulgaria: Critically endangered CR=[D + E], BDA-II, III; International: IUCN-VU, CITES-I, BeC-II, BoC-II, ECS-Spec 1, BD-I.
General distribution. A Palearctic species. It nests in Austria, the Czech Republic, Slovakia, Hungary, Romania, the Ukraine, Croatia, Serbia, Macedonia, Bulgaria, Greece, Russia, Georgia, Armenia, Turkey, Azerbaijan, Iran, Kazakhstan, Turkmenistan, Uzbekistan, Mongolia and China. It winters along the valley of the river Nile, the Arab peninsula, India, Southern and Eastern Asia. Some of the birds in Europe winter in Greece and Turkey, and in milder winters also in Bulgaria [1]. The European population numbers about 1 100 pairs, and the world population is about 6 200 pairs [2].
Distribution and abundance in Bulgaria. A breeding summer visitor, passage migrant and partly wintering species. At the beginning of the 20th century it was widespread, with an estimated abundance of 1 824 pairs [3]. In the middle of that century it was "one of the rare birds" [4] and, three decades later, only 3 certain and 6 probable breeding habiats were found [5]. In the last 20 years, a total of 19 certain breeding habitats was registered, in 3 physical geographic areas: the Srednogorie region [2], the Rhodopes [1] and the Central Tundzha valley [6].
Habitats. Mainly around deciduous and coniferous forests, meadows or pastures, but always near flowing water at a distance of up to 300 – 350 m.
Biology. The breeding period starts in March with the strengthening of the old nest or the building of new nests, with synchronous flights of the pair. In the first half of April, it lays 2 eggs, rarely 1 or 3-4 [6, 7]. The young ones fly away from the nests at the end of July and the beginning of August. Hamsters are a major component of the food [8, 9].
Similar species. The Golden Eagle (Aquila chrysaetos).
Negative factors. Disturbance caused by fires and forestation activities, felling trees with nests, poisoning by dead rodents after spraying poisons on the sown fields, etc.
Conservation measures taken. A protected species since 1962, included in the Red Data Book of Bulgaria (1985); its population has been the object of yearly monitoring since 1998; from 2 to 6 risk nests are guarded; 10 artificial platforms are mounted for breeding in the region of the mountains Central Balkans, Sredna Gora and Sakar; a National Plan for its conservation has been adopted [10].
Conservation measures needed. Declaring new natural protected territories, especially for the Imperial Eagle in the mountains Sredna Gora, the Eastern Rhodopes, Sakar, Derventski Vazvisheniya and Strandzha.
References. 1. Heredia et al., 1996; 2. BirdLife International, 2000; 3. Leverkuhn, 1905; 4. Patev, 1950; 5. Michev, Petrov, 1979, 1985; 6. Petrov, 1981; 7. Stoychev et al., 2004; 8. Simeonov, Petrov, 1980; 9. Petrov, 1999; 10. Petrov, Stoychev, 2002.
Authors: Tseno Petrov, Ivelin Ivanov, Simeon Marin, Stoycho Stoychev, Dimitar Demerdjiev
