Sex‐Biased and Density‐Dependent Natal Dispersal in a Highly Mobile but Philopatric Raptor

Natal dispersal plays an important role in the ecological and evolutionary processes of a species and has major implications for its conservation. Here, we studied natal dispersal patterns in the Pannonian population of the vulnerable eastern imperial eagle <i>Aquila heliaca</i> in regard to sex, local density, and dispersal direction. We defined local density at each nest as the reciprocal of the area of the Thiessen polygon drawn around the nest. Using the combined methods of colur-ringing, GPS tracking, and DNA profiling, we managed to determine natal dispersal distances for 116 chicks (43 males, 72 females, 1 with unknown sex) hatched in Hungary between 2012 and 2020. Eagles were highly philopatric, with all 116 individuals settling in the Pannonian population and only 4.3% of them emigrating from the eastern to the western subpopulation. Natal dispersal distance was female-biased (median: 57.6 km for females and 35.9 km for males). In general, birds settled at lower-density sites compared to their natal site but moved to higher-density sites from natal sites with low density. During the exponential population growth in the second period of the study, females dispersed mainly in a southern direction, towards low-density areas. Our results demonstrate that natal dispersal patterns in the imperial eagle are sex-dependent and are shaped by both intraspecific competition and conspecific attraction. The observed high philopatry implies the genetic uniqueness of the Pannonian population, making it of high conservation value.