Department of biology, chemistry and geography, UQAR
Des Ursulines Building
300 Allée des Ursulines
418.723.1986 extension 1566
Predator-mediated effects of herbivores on tundra nesting insectivorous birds
Global changes, particularly pronounced in the Arctic, threaten biodiversity and transform Arctic terrestrial communities. One of these transformations, observed at the circumpolar scale, is the explosion of geese populations. As geese reach record population levels, lemming cycles are fading in several parts of the Arctic and shorebird populations are experiencing marked declines at the circumpolar scale. Geese, lemmings and shorebirds share common predators and are therefore closely linked through indirect trophic interactions. Shared predation can affect species abundance and coexistence at the community level through a variety of indirect effects (e.g. apparent mutualism, apparent competition). Despite a large number of studies on trophic interactions involving shorebirds, predator-mediated effects of herbivores on shorebirds remain poorly understood. By adopting a multi-sites approach combined with long-term ecosystem monitoring, this thesis addresses predator-prey interactions and their potential indirect impact on shorebirds experiencing significant population declines. The main objective of my project is to determine the role of indirect trophic interactions on Arctic shorebirds. Specifically, we aim to i) determine predation thresholds that shorebird populations can support using population models, ii) define the nature of indirect interactions involving shorebirds by using empirically-based models and iii), investigate how changes in lemmings and geese population dynamics affect shorebirds demography. This project combines a theoretical and empirical approach in collaboration with researchers working in various sites at a circumpolar scale (Canada, United States, Norway, Russia and Greenland). This project also relies on long-term ecosystem monitoring datas (> 25 years) from Bylot Island (73 ° N, 79 ° W, NU). Understanding indirect interactions is necessary to maintain the ecological integrity of protected ecosystems and to preserve Arctic biodiversity. How species interact have fascinated and continue to generate great interest among the scientific community and the relative simplicity of the Arctic vertebrate community provides an ideal theoretical framework to address these questions.
Beardsell, A., Gauthier, G., Fortier, D., Therrien, J.-F., Bêty, J., 2017. Vulnerability to geomorphological hazards of an arctic cliff-nesting raptor, the rough-legged hawk. Arctic Science, 3(2): 203-219. DOI: 10.1139/AS-2016-0025.
Therrien, J.-F., Lecomte, N., Zgirski, T., Jaffré, M., Beardsell, A., Goodrich, L.J., Bêty, J., Franke, A., Zlonis, E., Bildstein, K.L., 2017. Long-term phenological shifts in migration and breeding-area residency in eastern North American raptors. The Auk: Ornithological Advances, 134: 871-881. DOI: 10.1642/AUK-17-5.1.
Beardsell, A., Gauthier, G., Therrien, J.-F., Bêty, J., 2016. Nest site characteristics, patterns of nest reuse, and reproductive output in an Arctic-nesting raptor, the Rough-legged Hawk. The Auk: Ornithological Advances, 133(4): 718-732. DOI: 10.1642/AUK-16-54.1.