Population connectivity of European Turtle Doves (Streptopelia turtur) : threats affecting European populations and modelling of species-habitat relationships at German breeding grounds
European Turtle Doves (Streptopelia turtur), Europe s only long distance migrating columbids, experienced a strong population decline of more than 78% since 1980. Studies about Turtle Dove s population connectivity and threats affecting the population are needed. Therefore, this dissertation aims to infer the population connectivity of Turtle Doves and evaluate the potential impact of hunt, with a) a ring re-encounter analysis (chapter 1) and b) a stable isotope assignment (chapter 2). Furthermore, prevalences and genetic lineages of the parasite Trichomonas gallinae were analysed (chapter 3) and species distribution models (SDMs) were applied to determine habitat requirements and potential key breeding areas in Germany (chapter 4).The first chapter suggests a strong connectivity for Turtle Doves in western Europe, mainly following a western flyway, and a rather weak connectivity for birds from central and eastern Europe, which used both, a central and an eastern flyway. The second chapter demonstrates that stable hydrogen isotopes could be used to distinguish four large areas within the breeding ranges, but also supports the suggestion of a weaker connectivity for some birds. The methods applied in both chapters could not identify spatially explicit breeding areas, but clearly demonstrated the high hunting impact on migrating birds in Europe, particularly on those originating from other countries than from those where hunting occurs. The evaluation for Trichomonas gallinae highlights a general high prevalence, but an infection with a highly pathogenic lineage could not be proven for Turtle Doves. However, as pathogenic lineages were already demonstrated in British Turtle Doves and were present in German Stock Doves (Columba oenas), present results should be taken seriously, due to potential epidemic outbreaks caused by possible inter- and intra-specific disease transfer at life-cycle stages. Germany wide applied SDMs using presence only (PO) data highlighted key breeding sites and were mainly driven by climatic variables, but the land use parameters available were not suitable to define specific local habitat characteristics. To specify those, other variables such as land management practices or soil type should be introduced in future SDMs.To conclude, the present dissertation shows the successful application of ring re-encounter analysis and stable isotope assignment to study the population connectivity and estimate a potential hunting impact on migrating Turtle Doves. Furthermore, a high prevalence of Trichomonas gallinae was demonstrated, which can become a serious threat due to its potentially epidemic character. Moreover, a possible breeding distribution across Germany was modelled, which highlights PO data as a powerful data source for SDMs.
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