| Institution: | 1.Department of Vertebrate Ecology and Zoology,University of Gdańsk,Gdańsk,Poland;2.Centre d’Ecologie et des Sciences de la Conservation,UMR 7204 MNHN-CNRS-UPMC-Sorbonne Universités,Paris,France;3.Fundación Global Nature,Palencia,Spain;4.Iberian Ringing Group (GIA-León),León,Spain;5.Departament of Biodiversity and Environmental Management,University of León,León,Spain;6.CIBIO/UP - Centro de Investiga??o em Biodiversidade e Recursos Genéticos,Universidade do Porto,Vair?o,Portugal;7.Molecular Ecology & Evolution Lab, MEMEG, Department of Biology,University of Lund,Lund,Sweden |
| Abstract: | Differential migration has been extensively reported in spring, but less so in autumn, particularly in relation to sex in monomorphic bird species. Here, we analysed the autumn passage of a monomorphic, globally threatened passerine, the Aquatic Warbler Acrocephalus paludicola throughout Western Europe, with regard to age and sex. We showed that, overall, adults migrated earlier than first-year birds, and males migrated earlier than females during the autumn migration. This may be caused by an overall social dominance of adults over immatures, and differentiated migration strategy of males and females. In addition, we found male-skewed sex proportions, with a tendency to an equalised ratio in more southern stopover sites. This may indicate a male bias in the global population or different migration strategies of the sexes. Differential migration may cause the age and sex classes to be exposed differently to various threats affecting demographic structure of the species. |
