Степной орёл в Республике Калмыкия (Россия): результаты исследования 2021 года

Abstract

The article presents the results of the Steppe Eagle (Aquila nipalensis) study in the Republic of Kalmykia. 135 breeding territories of eagles were examined and 155 birds were observed during summer registrations and counts. The average distribution density of the occupied breeding territories in 2021 in the main part of the area was 2.15 (1.54–2.99)/100 km², in the zone of the large number of food resources – 5.72 (4.45–7.35)/100 km². The percentage of occupied breeding territories was 71%, and 43% of the occupied territories were successful. The number of nestlings in broods ranged from 1 to 3, averaging 1.81±0.69 per successful nest (n=43) and 0.73±0.95 per occupied nest (n=105). The percentage of nests with dead clutches and nestlings was high at all surveyed plots. The main diet of eagles during the breeding period included the Little Ground Squirrel (Spermophilus pygmaeus) (44%) and several additional prey items. A preliminary assessment of habitat suitability for the Steppe Eagle in terms of food conditions was carried out using GIS methods. Based on the registration data and clarification of the breeding range borders (47086.7 km²), the number of the Steppe Eagle in Kalmykia was re-estimated at 789 (587–1059) pairs. The signs indicating a negative trend in the population intensified: the percentage of immature birds in breeding pairs was 27%, the percentage of abandoned breeding territories was 19%. There is a consolidation of breeding groups in the population nucleus with a simultaneous decrease in breeding density at the periphery. Among the negative anthropogenic factors in 2021 there were the following: mass mortality on power lines, destruction of the food potential by the locals, disturbance during breeding, probable taking away of nestlings from nests.