Mouvements et utilisation de l'habitat en hiver chez un prédateur nomade: le harfang des neiges

• Main Author: Robillard, Audrey
• Other Authors: Gauthier, Gilles, Bêty, Joël
• Format: Thesis
• Language: French
• Published: Université Laval 2017
• Subjects: envir; geo; Arctic; snowy owl; harfang des neiges
• Online Access: https://hdl.handle.net/20.500.11794/27894

Migration is an ecological process allowing individuals to exploit habitats where food resources and environmental conditions fluctuate seasonally. Some species have highly variable and unpredictable migratory behaviours, and especially facultative migrants. The general aim of this thesis is to better understand the wintering ecology of migratory species with unpredictable movement patterns during winter, which may affect their subsequent breeding. My project focused on the snowy owl, an avian predator considered both a nomadic and irruptive migrant. The specific objectives consisted in determining the interindividual variability in movements, habitat use, wintering site fidelity and contribution of prey from different habitats to their diet in winter through an approach integrating multiple analytical methods. To achieve this, 31 adult females were tracked by satellite telemetry between 2007-2016 to characterise space and habitat use and evaluate the impact of some environmental factors on them. Stable isotope analyses (¹³C et ¹⁵N) of feathers sampled on snowy owls in summer were used to estimate the contribution of marine and terrestrial habitats to their winter diet. Finally, citizen-based data on winter abundance of snowy owls from Christmas Bird Count coupled with estimates of summer prey abundance in the Arctic allowed to shed new lights on the causes of snowy owls’ winter irruptions at temperate latitudes. Satellite tracking confirmed the extensive use of the Arctic and marine environments by wintering snowy owls. Snow cover and lemming abundance could explain part of the interindividual variability in space use. We also show that snowy owls were generally consistent from one year to the next in their use of latitudinal zones (Arctic vs temperate areas) and habitats (terrestrial vs marine) in winter and that they showed a greater fidelity to wintering than to breeding sites. Our analyses show that periodic winter irruptions at temperate latitudes are at least in part attributable to high reproductive ...