Department of biology, chemistry and geography
Joël Bêty (Regular member)
IntroductionNatural communities are structured by a network of interactions between species, which are modulated by the geomorphological environment. Arctic fox predation on birds’ nests in the High Arctic can have a significant effect on their reproductive success. The structure of the environment can generate physical barriers to fox movements and thus create refuges for birds. Birds may use these refuges to reduce or eliminate the risk of predation. Thus, the availability and spatial distribution of refuges could be key determinants of the abundance and distribution of Arctic bird species. ObjectivesThis project aims to better understand the effect of refuges on the spatial distribution and abundance of birds in the Arctic tundra. To achieve this, we need to characterize the available refuges (i.e. islands in lakes and wetlands), to experimentally measure the risk of predation on birds' nests and to analyze the selection of these refuges by different species of birds (geese, loons, gulls) based on their characteristics. Study sitesThis project will be realised at Bylot Island in Sirmirlik National Park, Nunavut, Canada (73°08'N, 80°00'W). Field work will take place on the southern plain of the island, where the landscape is characterized by wetlands and mesic tundra, punctuated by lakes of various sizes and islands with different distance to shore and water depth. Material and methodsI will benefit from various available databases (i.e. on physical characteristics of the environment and on the distribution of several species of breeding birds) to characterize the available islands and to analyze the selection of islands by birds. I will also carry out field experiments with artificial nests in order to obtain a standardized measure of predation risks for refuges with different characteristics. Expected resultsWe anticipate that (i) refuges will either reduce (partial refuge) or eliminate (total refuge) the risk of predation, and (ii) that these effects are determined by thresholds, which in turn are determined by biomechanical constraints (e.g., leg length and ability to pounce) that limit the movement of foxes in the physical landscape.
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