Long-term Population Survey of the Eastern Imperial Eagle in the Thracian Eco-region (Bulgaria and Turkey)

Abstract

The Thrace geographical region comprises territories of three states and covers an area of about 70,000 km2. At the end of the 19th century, the Eastern Imperial Eagle (Aquila heliaca) was widespread throughout the region, occupying a variety of habitats. The mid-20th century marked the beginning of its dramatic decline, and in the latter half of the century the birds breeding in Northern Thrace amounted to 15-20 pairs, Eastern Thrace harbored scattered pairs along the lower reaches of the Maritsa River, while in Western Thrace the population was estimated at 6-10 pairs only. Since 2000, the systematic conservation activities implemented by Bulgarian NGO’s have improved the status of the Imperial Eagle in Bulgaria (Northern Trace). At the same time, in Western Thrace (the Greek part), only one pair was confirmed by the Dadia Reserve. Since 2008, intensive field research in European Turkey identified an abundant and stable population of the species. In Bulgaria, 44 different breeding territories were established, while in European Turkey the number of identified breeding territories was 48. Most of the pairs were distributed in the European Green Belt area, along the former Iron Curtain, were human access had been strictly limited, thus preserving extremely rich biodiversity. Based on a long-term population survey of these species in Bulgaria and European Turkey, we estimated this sub-population of the species at about 80–90 breeding pairs. Breeding of several pairs in Greece, in the Greece-Turkey border area, along the Evros River, is also possible.

Keywords

• birds of prey
• imperial eagle
• aquila heliaca