Successful Breeding of a Ten-Year-Old Hybrid Spotted EagleAquila clanga×A. pomarinaRetaining Immature Plumage Characters

Abstract

Greater Spotted Eagle Aquila clanga and Lesser Spotted Eagle Aquila pomarina are hybridising Eurasian raptors, but our knowledge of hybrid fertility is poor. Here, I present a case of interbreeding between a F1 hybrid spotted eagle male and a Lesser Spotted Eagle female in Estonia. The hybrid was first studied and ringed as a nestling in 1999, showing characters of both species. In 2009, the same bird was caught and, surprisingly, this ten-year-old individual had retained several immature characters. Again, characters of both species were recorded in the hybrid, as well as in his backcross-offspring. At the nest site level, the habitat of the hybrid's hatching site was intermediate but its nesting site was typical of A. pomarina. At the landscape level hatching and breeding sites resembled habitat typical of A. clanga in Estonia.