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Démographie de l’hirondelle bicolore: le déclin d’une population d’insectivore aérien.
De nombreuses espèces d'oiseaux sont en déclin en Amérique du Nord. La situation des insectivores aériens est particulièrement inquiétante. Par exemple, l'abondance des hirondelles bicolores a diminué de 4,2% par an au cours des 20 dernières années au Québec. Le principal suspect de ce déclin a longtemps été l'intensification des pratiques agricoles dans les aires de reproduction. L'intensification agricole (IA) est caractérisée par l'homogénéisation du paysage et de l'habitat et l'utilisation accrue de pesticides. Tous ces facteurs pourraient affecter négativement la valeur adaptative de l'hirondelle bicolore, soit directement, soit indirectement par une réduction de la disponibilité des ressources. Cependant, malgré de nombreuses études, nous ne trouvons que de faibles effets négatifs de l’IA sur la reproduction et la survie. Cela nous porte donc à croire que la dégradation des conditions environnementales lors de la migration ou durant l'hivernage pourrait jouer un rôle dans le déclin observé chez l'hirondelle bicolore dans le sud du Québec. Le but de mon étude est de (a) construire un modèle de capture-recapture pour estimer les taux vitaux de l'hirondelle bicolore en fonction de l'IA et du climat pendant les migrations et l'hiver. Je vais ensuite (b) construire un modèle démographique pour quantifier l’importance relative de ces facteurs dans le déclin observé et faire des projections des tendances démographiques attendues selon divers scenarios. |
Demography of tree swallow: explaining the contemporary decline of an aerial insectivore population.
Many species of bird have shown declines abundance in north America. Most worrisome among them are aerial insectivore. For example, tree swallow abundance has declined by 4.2 % per year over the past 20 years in Québec. The prime suspect for this decline has long been the intensification of agricultural practices in breeding grounds. Agricultural intensification (AI) is characterized by homogenization of landscape and habitat structure and the augmented use of pesticides. All of these were expected to negatively affect fitness on tree swallow either directly, or indirectly via a reduction in resource availability. However, despite numerous studies, we only find weak negative impact of AI on reproduction and survival. This leads us to believe that degraded environmental conditions during migration or in wintering habitat, may play a role in the observed decline of tree swallow in southern Quebec. The aim of my study is to (a) build a capture-recapture model to estimate vital rates of tree swallow as a function of AI and climate during migrations and winter. I will then (b) build a demographic model to quantify the relative role of these factors in driving the observed decline and make projections of expected population trends.
Many species of bird have shown declines abundance in north America. Most worrisome among them are aerial insectivore. For example, tree swallow abundance has declined by 4.2 % per year over the past 20 years in Québec. The prime suspect for this decline has long been the intensification of agricultural practices in breeding grounds. Agricultural intensification (AI) is characterized by homogenization of landscape and habitat structure and the augmented use of pesticides. All of these were expected to negatively affect fitness on tree swallow either directly, or indirectly via a reduction in resource availability. However, despite numerous studies, we only find weak negative impact of AI on reproduction and survival. This leads us to believe that degraded environmental conditions during migration or in wintering habitat, may play a role in the observed decline of tree swallow in southern Quebec. The aim of my study is to (a) build a capture-recapture model to estimate vital rates of tree swallow as a function of AI and climate during migrations and winter. I will then (b) build a demographic model to quantify the relative role of these factors in driving the observed decline and make projections of expected population trends.