Habitat Requirements of the Lesser Spotted Eagle Clanga pomarina Brehm, 1831 (Ayes: Accipitridae) at the Southern Periphery of the Distribution Range (Southeast Bulgaria)

摘要

Analyzing the habitat requirements of raptors is of crucial importance for wildlife conservation, since their role as bioindicators serves to assess the impact of different factors - anthropogenic, biotic and abiotic, as well as the "stress level" on the entire ecosystem. The Lesser Spotted Eagle is a strongly philopatric and territorial forest-dwelling raptor that tends to prefer foraging in different types of grasslands and avoid arable land. With regard to the micro-habitat selection, the eagle's selectivity was strongly related to the topography and the proximity to open areas and water bodies, avoiding small forest patches. In the nesting stands the eagle definitely selected older and taller trees. The territory selection was related to the preferences for natural grasslands, agricultural mosaic and shrubs as well as the avoidance of large forests and arable land. The mean size of the fragments influenced significantly the selection of a home range by this raptor species, with a strong preference for large patches of grassland biotopes and shrubs, and strict avoidance of large forest tracts. The strongest habitat preferences were related to the habitat heterogeneity, so we observed that the species clearly selected territories of high habitat diversity. We found out that the habitat structure did not affect significantly the eagle's density. Although the habitats of the species vary across its distribution area, in general the species follows the same habitat selection patterns throughout its European range. We would like to emphasize that the conservation of the habitats of this raptor should include not only conservation of nest sites, but also conservation of favourable foraging sites. Inappropriate practices in forest and agriculture management can adversely affect the species' population both at a micro-habitat scale and as macro-habitat features by decreasing the quality of habitats. The significance of old growth trees, structurally diverse stands, share and condition of grasslands as well as landscape diversity must be taken into account in the management and the decision making related to the protection of the Lesser Spotted Eagle.