Long-term monitoring of breeding activity of avian predators on Bylot Island, Nunavut

Predators may play a key role in the functioning of arctic tundra ecosystems and could potentially control the abundance of their prey. Avian predators, mostly raptors and seabirds, are the most diverse groups of predators in the Arctic and range from highly specialists to highly generalists. Measuring annual variation in their abundance is thus essential to understand trophic interactions in the tundra. Annual reproductive success sets the stage for an individual's contribution to the gene pool and is one of the determinants of population growth (or decline). It is governed by a depreciative process that starts with an initial investment of eggs and ends (from a northern perspective) with the fledging of young and their movement south during migration. The depreciation involves a cascade of interactions with the habitat (e.g. quantity and quality of forage), competitors, predators and parasites. In many areas, predation is the leading cause of nesting failure in birds, and thus nesting success is a major component of predator-prey interactions. Quantifying the annual variation in their diet (through blood samples or regurgitation pellets) according to the availability of their prey will also help us better understand trophic interactions in the tundra.