Janvier 2020 : Taille et dynamique de la population de grands tétras dans le canton de Schwyz

    Une étude réalisée dans le canton de Schwyz entre 2009 et 2015 a fourni des estimations de la taille de la population, de la survie et de la reproduction de la population locale de grands tétras. Une nouvelle publication vient de paraître. Pour des raisons légales, nous ne sommes pas autorisés à mettre à disposition le PDF pour téléchargement, mais il peut être demandé chez Pierre Mollet (pierre.mollet@vogelwarte.ch).

     

    Augustine, B. C., M. Kéry, J. Olano Marin, P. Mollet, G. Pasinelli & C. Sutherland (2019): Sex-specific population dynamics and demography of capercaillie (Tetrao urogallus L.) in a patchy environment.

    Abstract
    Modeling the population dynamics of patchily distributed species is a challenge, particularly when inference must be based on incomplete and small data sets such as those from most species of conservation concern. Here, we develop an open population spatial capture–recapture (SCR) model with sex-specific detection and population dynamics parameters to investigate population trend and sex-specific population dynamics of a capercaillie (Tetrao urogallus) population in Switzerland living in eight distinct forest patches totaling 22 km2 within a region of 908 km2 and sampled via scat collection. Our model accounts for the patchy distribution of habitat and the uncertainty introduced by collecting data only every third year, while producing sex by patch population trajectories. The estimated population trajectory was a decline of 2% per year; however, the sex specificity of the model revealed a decline in the male population only, with no evidence of decline in the female population. The decline observed in males was explained by the demography of just two of the eight patches. Our study highlights the flexibility of open population SCR models for assessing population trajectories through time and across space and emphasizes the desirability of estimating sex-stratified population trends especially in species of conservation concern.