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Marius  Somveille

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Presentation of the results of a joint PhD thesis at the University of Cambridge + CEFE

Le vendredi 31 juillet 2015 - Grande salle de réunion du CEFE - 1e étage, aile C - 11h30

Thesis summary:

Nearly twenty percent of bird species are migratory, their seasonal movements causing a redistribution of bird diversity that radically changes avian community composition worldwide. And yet, bird migration has been largely ignored in studies of global avian biodiversity. This thesis is the first macroecological study of the global bird migration system, using the global patterns of migratory bird diversity to test hypotheses for the ecological processes driving bird distributions in space and time.

Using a dataset on the geographical distributions of the world’s birds, I started by mapping global diversity patterns associated with bird migration. Despite their great biological and ecological diversity, strong spatial patterns emerge when all migratory species are pooled together. I have followed a diversity of approaches to test hypotheses for the ecological patterns underpinning these processes. First, results of correlative statistical models strongly indicate that migratory birds move to their breeding grounds to exploit a seasonal surplus in energy and resources, and then redistribute to the nearest suitable non-breeding grounds. Second, I have found that, underneath their great diversity of breeding and non-breeding destinations, migratory birds appear to follow a common strategy of tracking their climatic niche year-round, within a broader trade-off between the costs of migration and the benefits of better access to resources. From the results of these statistical correlative analyses, I then developed a global spatially-explicit, process-based, mechanistic model of the global bird migration system. Building from first principles (to account for the energy use by species across the year and including key ecological and biological processes), this model successfully explains the diversity patterns of migratory bird diversity I had previously quantified.

Overall, this thesis advances understanding of the mechanisms driving bird migration worldwide, shedding light into one of Nature’s most fascinating phenomenon.

Overall, this thesis advances understanding of the mechanisms driving bird migration worldwide, shedding light into one of Nature’s most fascinating phenomenon.

Publications:

Somveille, M., Rodrigues A.S.L., Manica, A. (in press) Why do birds migrate? A macroecological perspective. Global
Ecology and Biogeography.

Somveille, M., Manica, A., Butchart, S.H.M., Rodrigues A.S.L. (2013) Mapping Global Diversity Patterns for Migratory Birds. PLoS ONE 8: e70907.

Thesis supervisors: Andrea Manica (Dep. of Zoology, University of Cambridge) and Ana Rodrigues (équipe DPB, CEFE)