| Summary: | Degree: Doctor of Philosophy Abstract: Specialist predators with a limited diet may be less adaptable to environmental change than generalists, which consume a diversity of prey. As the climate changes, ecological homogenization is occurring, where generalist species outcompete specialists, reducing ecosystem complexity. In Arctic ecosystems, temperatures are rising at almost twice the rate of the rest of the planet and summer rainfall has increased significantly over the last century. Arctic peregrine falcons (Falco peregrinus. tundrius) breeding throughout the circumpolar regions of Canada, the USA, and Greenland have a diversity of prey species to choose from, but little is known about how they select for these resources as prey populations fluctuate. To fully appreciate the potential implication of climate change on Arctic peregrine falcon populations, research investigating prey selection and the potential for peregrines to switch to alternative prey is needed. In this dissertation I studied an Arctic tundra ecosystem around Igloolik, Nunavut, and related spatiotemporal variations in all prey species consumed by peregrines to annual variation in weather, while simultaneously monitoring peregrine diet and reproductive output. First, I investigated the relationship between annual variation in weather and spatiotemporal variation in the abundance of multiple avian guilds: songbirds (Passeriformes), shorebirds (Scolopacidae and Charadriidae), gulls (Laridae and Sternidae), loons (Gaviiformes), geese and ducks (Anatidae), and black guillemots (Cepphus grylle). I spatially stratified my study area and conducted distance sampling to estimate strata-specific densities of each guild during the summers of 2010-2012 while also monitoring temperature and rainfall. Shorebirds, songbirds and gulls were less abundant in 2012, which was a cool and wet summer, relative to 2010 and 2011. I monitored annual variation in lemming abundance using snap trapping and assumed spatial variation in lemming density was proportional to ...
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