Challenging conservation of migratory species: Sahelian rainfalls drive first-year survival of the vulnerable Lesser Kestrel Falco naumanni |
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Authors: | Jean-Baptiste Mihoub Olivier Gimenez François Sarrazin |
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Institution: | a Université Pierre et Marie Curie, UMR 7204 MNHN-CNRS-UPMC “Conservation des Espèces, Restauration et Suivi des Populations”, CP 51, 61 rue Buffon, F-75005 Paris, France b Centre d’Ecologie Fonctionnelle et Evolutive, Campus CNRS, UMR 5175, 1919 Route de Mende, F-34293 Montpellier Cedex 5, France c LPO Mission Rapaces, 26 Avenue Alain Guigue, F-13104 Mas-Thibert, France |
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Abstract: | In the context of attested global changes, accurate estimation of whether climatic fluctuations impact on population demographic parameters is needed for adequate management, especially for migratory species. We present a capture-recapture analysis linking survival rates of the vulnerable Lesser Kestrel (Falco naumanni) to annual rainfalls in the Sahel region, considered as a proxy of climatic conditions on wintering grounds. Recapture data were obtained from field observations of individuals ringed and sexed as juveniles over a 14-year monitoring period (1994-2007). We addressed a common but problematic situation in birds where: (i) sex is known with certainty for first-summer or older birds but only suspected for juveniles, and (ii) a large proportion of individuals never return to the study population (e.g. transient behavior). Transient behavior and unknown sexes were explicitly integrated considering a two age class in a multistate capture-recapture model. Survival was time-varying for juveniles (geometric mean: 0.499 ± 0.021) but constant - and higher - for adults (0.718 ± 0.013). Yearling survival probabilities were strongly correlated with rainfalls in the Sahel, suggesting a high dependence of juvenile upon the wintering conditions. While taking sex uncertainty into account, we detected no sex-dependence in survival. Incorporating the sensitivity of survival of wintering migratory birds to climatic variables such as precipitations in arid Sahelian ecosystem may allow to model conservation scenarios with a greater realism. Finally, we encourage the development of international management strategies for migratory species on wintering areas in addition to the existing conservation actions on summering Mediterranean grounds. |
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Keywords: | Capture-recapture Global changes Raptor conservation Wintering grounds |
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