No adverse effects on Lesser Spotted Eagle breeding in an area of high White-tailed Eagle density

Abstract

Mesopredators frequently suffer lethal and/or non-lethal negative effects when breeding in sympatry with more powerful apex predators. The recent recovery of the White-tailed Eagle Haliaeetus albicilla (WTE) population throughout its range indicates the return of the largest predator of the raptor communities there. In this study, we assess the importance of habitat overlap and spatial distribution to the reproduction of the Lesser Spotted Eagle Clanga pomarina (LSE), a species that breeds sympatrically in areas of high WTE density near the Baltic Sea, but is three times smaller than the latter. Fewer water bodies surround the nesting sites of the LSE, and it uses agricultural areas and transitional habitats more frequently than the WTE. The same breeding territories are faithfully occupied by the LSE annually, irrespective of the distance between these and those of the WTE. We found that the breeding success of the LSE was not affected by the proximity or breeding output of the nearest pair of WTEs, nor was this affected by the number of WTE pairs present within a 3-km radius of nests. Our data suggest that the smaller LSE coexists with an abundant top predator without any obvious adverse effects on its population dynamics.