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Assessment of hypotheses about dispersal in a long-lived seabird using multistate capture–recapture models

Authors

  • Emmanuelle Cam,

    Corresponding author
    1. Institut Mediterrani d’Estudis Avançats (IMEDEA), CSIC-UIB, 07190 Esporles, Mallorca, Spain, and Laboratoire Evolution et Diversité Biologique, UMR CNRS 5174 – Bât. 4R3, Salle 209, Université P. Sabatier, Toulouse III, 118 route de Narbonne, 31062 Toulouse Cedex 04, France;
      Emmanuelle Cam, Laboratoire Evolution et Diversité Biologique, UMR CNRS 5174, Bât. 4R3, Salle 209, Université P. Sabatier, Toulouse III, 118 route de Narbonne, 31062 Toulouse cedex 04, France. Fax: + 33561557327; E-mail: emmacam@cict.fr
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  • Daniel Oro,

    1. Institut Mediterrani d’Estudis Avançats (IMEDEA), CSIC-UIB, 07190 Esporles, Mallorca, Spain;
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  • Roger Pradel,

    1. Centre d’Ecologie Fonctionnelle et Evolutive, CNRS, 1919 route de Mende, 34293 Montpellier Cedex 5, France
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  • Juan Jimenez

    1. Servicio de Conservación y Gestión de la Biodiversidad, Dirección General de Planificación y Gestión del Medio, Francisco Cubells 7, 46011 Valencia, Spain
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Emmanuelle Cam, Laboratoire Evolution et Diversité Biologique, UMR CNRS 5174, Bât. 4R3, Salle 209, Université P. Sabatier, Toulouse III, 118 route de Narbonne, 31062 Toulouse cedex 04, France. Fax: + 33561557327; E-mail: emmacam@cict.fr

Summary

  • 1Dispersal contributes to spatio-temporal variation in population size and is a key process in studies of life history evolution and studies with conservation implications. However, dispersal is still one of the major gaps in our knowledge of ecological dynamics. The very large literature on metapopulation dynamics lacks empirical bases on dispersal and relevant behavioural parameters. We used multistate capture–recapture models (data from 1988 to 2001) to address hypotheses about movement probability and habitat selection within a system of two breeding colonies in Audouin's gulls (Larus audouinii), an endemic species breeding in the Mediterranean and considered as threatened.
  • 2Movement probability varied over time, and differed greatly between the colonies.
  • 3We did not find evidence of an influence of colony size or density of predators on movement probability.
  • 4In dispersers, our results did not support the hypotheses that movement probability between year t and t+ 1 was influenced by mean breeding success in the colony of origin (i.e. an indicator of habitat quality) or the destination colony in year t or t+ 1, or by the ratio of breeding success in these colonies in year t or t + 1 (i.e. quality gradient).
  • 5Overall, movement probability was higher from the smaller colony to the larger, and from the colony with lower breeding success in year t to the more productive one. This provides slight support for two nonexclusive hypotheses about habitat selection (conspecific attraction and conspecific success attraction).
  • 6Movement probability from the smaller, less productive colony was very high in some years, suggesting that the dynamics of both colonies were strongly influenced by adult dispersal. However, in absolute numbers, more individuals moved from the larger, more productive colony to the smaller one. This suggests that the system may function as a source–sink system.
  • 7Use of multistate models to re-assess local survival showed that survival was lower in the less productive colony with higher emigration probability. This may reflect genuine differences in mortality between colonies, or more probably differences in permanent emigration from the study area.

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