Natal philopatry: local experience or social attraction? An experiment with Spanish imperial eagles

We investigated juvenile dispersal strategy of a territorial long-lived species with deferred maturity, the Spanish imperial eagle, Aquila adalberti. Here we used a reintroduction programme as an experimental approach to test separately predictions of the two hypotheses about natal philopatry: social attraction and local experience. We determined the maximum juvenile dispersal distance of 90 young eagles in three different categories: (1) 31 translocated young released without adults in the area; (2) 29 translocated young released with adults breeding in the area; and (3) 30 wild nonmanipulated individuals. No differences between the sexes were found but there was a highly significant difference between the three categories, with longer distances in young released without adults in the area and similar distances in the other two categories. Our results thus showed that social attraction determined the juvenile dispersal strategies in this species.