Assessing the impact of climate variation on survival in vertebrate populations

Authors

  • V. Grosbois,

    Corresponding author
    1. Centre d’Ecologie Fonctionnelle et Evolutive, UMR 5175, 1919 Route de Mende, F-34293 Montpellier Cedex 5, France
    2. Laboratoire Biométrie et Biologie Evolutive, UMR 5558, Bat. Gregor Mendel Université Claude Bernard Lyon 1, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France
      * Tel: 0033 (0)4 72 44 81 70; Fax: 0033 (0)4 72 43 13 88; E-mail: vladimirgrosbois@hotmail.com
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  • O. Gimenez,

    1. Centre d’Ecologie Fonctionnelle et Evolutive, UMR 5175, 1919 Route de Mende, F-34293 Montpellier Cedex 5, France
    2. University of St Andrews, the Observatory, Buchanan Gardens, St Andrews, FIFE, Scotland, KY16 9LZ.
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  • J.-M. Gaillard,

    1. Laboratoire Biométrie et Biologie Evolutive, UMR 5558, Bat. Gregor Mendel Université Claude Bernard Lyon 1, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France
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  • R. Pradel,

    1. Centre d’Ecologie Fonctionnelle et Evolutive, UMR 5175, 1919 Route de Mende, F-34293 Montpellier Cedex 5, France
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  • C. Barbraud,

    1. Centre d’Etude Biologique de Chizé, CNRS UPR 1934, F-79360 Villiers en Bois, France
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  • J. Clobert,

    1. Laboratoire Evolution et Diversité Biologique, Station Biologique du CNRS a Moulis, Moulis, F-09200 Saint-Girons, France
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  • A. P. Møller,

    1. Laboratoire de Parasitologie Evolutive, CNRS UMR 7103, Université Pierre et Marie Curie, Bâtiment A, 7ème étage, 7 quai St. Bernard, Case 237, F-75252 Paris Cedex 05, France
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  • H. Weimerskirch

    1. Centre d’Etude Biologique de Chizé, CNRS UPR 1934, F-79360 Villiers en Bois, France
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Errata

This article is corrected by:

  1. Errata: Corrigendum Volume 84, Issue 3, 515, Article first published online: 23 July 2009

* Tel: 0033 (0)4 72 44 81 70; Fax: 0033 (0)4 72 43 13 88; E-mail: vladimirgrosbois@hotmail.com

Abstract

The impact of the ongoing rapid climate change on natural systems is a major issue for human societies. An important challenge for ecologists is to identify the climatic factors that drive temporal variation in demographic parameters, and, ultimately, the dynamics of natural populations. The analysis of long-term monitoring data at the individual scale is often the only available approach to estimate reliably demographic parameters of vertebrate populations. We review statistical procedures used in these analyses to study links between climatic factors and survival variation in vertebrate populations.

We evaluated the efficiency of various statistical procedures from an analysis of survival in a population of white stork, Ciconia ciconia, a simulation study and a critical review of 78 papers published in the ecological literature. We identified six potential methodological problems: (i) the use of statistical models that are not well-suited to the analysis of long-term monitoring data collected at the individual scale; (ii) low ratios of number of statistical units to number of candidate climatic covariates; (iii) collinearity among candidate climatic covariates; (iv) the use of statistics, to assess statistical support for climatic covariates effects, that deal poorly with unexplained variation in survival; (v) spurious detection of effects due to the co-occurrence of trends in survival and the climatic covariate time series; and (vi) assessment of the magnitude of climatic effects on survival using measures that cannot be compared across case studies. The critical review of the ecological literature revealed that five of these six methodological problems were often poorly tackled. As a consequence we concluded that many of these studies generated hypotheses but only few provided solid evidence for impacts of climatic factors on survival or reliable measures of the magnitude of such impacts.

We provide practical advice to solve efficiently most of the methodological problems identified. The only frequent issue that still lacks a straightforward solution was the low ratio of the number of statistical units to the number of candidate climatic covariates. In the perspective of increasing this ratio and therefore of producing more robust analyses of the links between climate and demography, we suggest leads to improve the procedures for designing field protocols and selecting a set of candidate climatic covariates. Finally, we present recent statistical methods with potential interest for assessing the impact of climatic factors on demographic parameters.

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