STEPPE EAGLE BREEDING SUCCESS
Mongolia's Eastern Steppe region supports the largest wild population of steppe eagles (Apuila nippalensis) in the world. The steppe eagle is an endangered species internationally and population declines have been confirmed in numerous distributed sites.
With the support of the Oriental Bird Club (OBC) Conservation Fund, we started a breeding success and prey abundance survey in the region in 2018. The project evaluates of nesting habitat requirement, food availability, nestling and fledgling survival, nestling growth and mortality reason.
The eagle monitoring site has been set up in 4676 km square area of Halzan Soum, Sukhbaatar Province, Mongolia. In the first year of study, 25 breeding nests have been studied in the steppe region including 13 (52%) were placed on the ground of flat steppe, 12 (48%) were on boulders of rocky hill sides. However, the nesting substrate did not affect hutching success, breeding success was higher in rock boulder habitat than flat steppe. Average clutch size was 2.4 (±0.13 SD, 1-3, n=25) and the number of young fledged per pair was 1.2 (±0.2 SD, 1-3, n=25). For most raptors, breeding success is limited by food supply and nesting site availability. When 98 Brandt’ vole in a per hectar area, the steppe eagle clutch size was 2.4 and a higher number than any other Eastern Mongolian study.