Genetic determination of migration strategies in large soaring birds: evidence from hybrid eagles

Abstract

The relative contributions of genetic and social factors in shaping the living world are a crucial question in ecology. The annual migration of birds to their wintering grounds and back provides significant knowledge in this field of research. Migratory movements are predominantly genetically determined in passerine birds, while in large soaring birds, it is presumed that social (cultural) factors play the largest role. In this study, we show that genetic factors in soaring birds are more important than previously assumed. We used global positioning system (GPS)-telemetry to compare the autumn journeys and wintering ranges of two closely related large raptorial bird species, the greater spotted eagle and the lesser spotted eagle, and hybrids between them. The timing of migration in hybrids was similar to that of one parental species, but the wintering distributions and home range sizes were similar to those of the other. Tracking data were supported by habitat suitability modelling, based on GPS fixes and ring recoveries. These results suggest a strong genetic influence on migration strategy via a trait-dependent dominance effect, although we cannot rule out the contribution of social interactions.

Flying on their own wings: young and adult cuckoos respond similarly to long-distance displacement during migration

“…For long-distance migrants, satellite tracking allows spatially unbiased study of the behavioural responses to displacement but few experiments have been performed in first-time migrants, and all of these have focussed on social migrants where group orientation might be guided by experienced individuals. Displacement experiments with young white storks Ciconia ciconia 32 and relocations of lesser spotted eagles Clanga pomarina for re-introduction 33 indicated a less precise migration programme with birds being dependent on social interactions to complete normal migrations as also indicated by a study on hybrids between lesser and greater spotted eagles Clanga clanga 34 . The initial uncompensated movements could indicate navigation based on inherited "signposts" 35,36 and they align well with observations from the marine environment, where navigation in inexperienced animals appears to be based on navigational markers (a simple look-up table 37 ).…”

High genetic diversity and low differentiation retained in the European fragmented and declining Greater Spotted Eagle (Clanga clanga) population

“…Individual Greater Spotted Eagles breeding in one area can spend their non-breeding time in places that are distant from one another. For instance, birds from the Estonian and Polish populations we studied, winter across a huge longitudinal range from south-western Europe to the Middle East and north-east Africa 49–51 . The two groups detected by microsatellites in the current study may also be linked to different migration routes and destinations, and this may have also increased the differentiation found in the east-west gradient.…”

Intergeneric Hybridization of a Vagrant Common Black Hawk and a Red-Shouldered Hawk

“…Greater (Clanga clanga) and Lesser Spotted Eagle (C. pomarina) hybrids were intermediate in plumage but large in size (Vali and Lohmus 2004). Behaviorally, they migrated early like the Lesser Spotted Eagle, but their winter distributions and home range sizes were more similar to those of the Greater Spotted Eagle (Vali et al 2018). In a study of large falcon hybrids (Falco spp.…”