Geology topics

E. A. Bragin

Publications and source records attributed to E. A. Bragin.

3 recordsLinked to original sources

USGS2022

Migration of first-year steppe eagles (Aquila nipalensis) from northern Kazakhstan and implications for conservation

Extensive anthropogenic alteration of steppe ecosystems throughout Eurasia leaves central Asia with some of the world’s last remaining large expanses of grassland habitat. Steppe eagles (Aquila nipalensis) are globally endangered breed primarily in these steppe ecosystems. We evaluated migratory movements of first year steppe eagles hatched in northern Kazakhstan, to understand their migration and the extent to which their movements expose them to threats that may impact population viability. Most steppe eagles we monitored migrated to the east of the Caspian Sea to wintering grounds on the Arabian Peninsula or northeastern Africa, although a few migrated to the west of the Caspian Sea, one wintered in southcentral Iran, and one in southern Pakistan. Northbound migration routes largely mirrored southbound routes. Straight-line distance between summering and wintering grounds averaged 3,582 km (fall) and 3,700 km (spring), and actual distance traveled averaged 7,183 km (fall) and 9,433 km (spring). Routes of travel of these steppe eagles expose them to potential electrocution, shooting, and wildlife trade across the extent of their migratory and wintering areas.

Aktobe, Kostanay↗

USGS2006

Spatial structure in the diet of imperial eagles Aquila heliaca in Kazakhstan

We evaluated the relationship between spatial variability in prey and food habits of eastern imperial eagles Aquila heliaca at a 90,000 ha national nature reserve in north-central Kazakhstan. Eagle diet varied greatly within the population and the spatial structure of eagle diet within the population varied according to the scale of measurement. Patterns in dietary response were inconsistent with expectations if either ontogenetic imprinting or competition determined diet choice, but they met expectations if functional response determined diet. Eagles nesting near a high-density prey resource used that resource almost exclusively. In contrast, in locations with no single high-density prey species, eagles' diet was more diverse. Our results demonstrate that spatial structuring of diet of vertebrate predators can provide important insight into the mechanisms that drive dietary decisions. ?? OIKOS.

Journal of Avian Biology↗

USGS2003

Coexistence in a multispecies assemblage of eagles in central Asia

We evaluated factors that permit species coexistence in an exceptional assemblage of similar raptor species at the Naurzum Zapovednik (a national nature reserve) in north-central Kazakhstan. White-tailed Sea-Eagle ( Haliaeetus albicilla ), Imperial Eagle ( Aquila heliaca ), Golden Eagle ( A. chrysaetos ), and Steppe Eagle ( A. nipalensis ) all breed at the Zapovednik. Steppe Eagle use of nesting resources was distinct from that of tree-nesting species. We evaluated differences in nest tree and nest habitat characteristics, nest dimensions and positions, and nest spacing among the three forest-dwelling eagle species to distinguish between the effects of inter- and intraspecific resource limitations on species coexistence. Although the different species bred in similar habitat and sometimes reused other species' nests, the dimensions, positions and locations of their nests often differed. These differences did not appear to result from interspecific competition. Nest spacing trends were also species specific; Imperial Eagles generally nested farther from other eagle nests than did Golden Eagles and White-tailed Sea-Eagles. Intraspecific variation in habitat, physical characteristics, and spacing patterns of Imperial Eagle nests was extensive throughout the nature reserve. Although interspecific partitioning of nesting habitat may allow coexistence of ground-nesting Steppe Eagles, interspecific competition did not appear to be a primary determinant of the use of nest habitat, space, or nests by tree-nesting species. Rather, interspecific effects appeared secondary to intraspecific effects in determining coexistence of tree-nesting eagles at this site.

Naurzum Zapovednik↗