Environmental change, seasonal interactions, and demographic responses of arctic-breeding birds

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Many shorebird species travel the length of the hemisphere from breeding grounds in the Arctic to wintering grounds in Central and South America. The conditions they encounter throughout the annual cycle can have interactive and profound influences on behaviour, physiological condition and ultimately demography. These seasonal interactions, or carry-over effects, can explain patterns that would be inexplicable at any one site in isolation and are increasingly viewed as important determinants of demographic processes. The harsh and unpredictable breeding conditions of the Arctic provide substantial variation with which to test hypotheses about seasonal interactions. This, coupled with arctic-breeding shorebirds' use of a restricted set of stopover sites during migration, makes for an ideal system within which to study the role of carry-over effects.****** My long-term research objective is to understand the times and locations at which populations of arctic birds are limited. Carry-over effects among seasons may play a crucial role in these demographic constraints. This proposal explores 1) how life history and individual behaviour influence the timing of arrival to the breeding grounds, body condition upon arrival and timing of breeding, 2) whether and how energetic constraints during the breeding season translate into fitness costs and 3) how environmental conditions at staging sites, including extreme weather events, can influence the timing of migration and birds' survival through the migratory phase. Collectively, these projects contribute to an understanding of shorebirds' population regulation throughout the annual cycle. *** *** The progression from site-based studies to whole-life-cycle modelling represents an important paradigm shift for ecologists in North America. The links among phases of the annual cycle are both fertile ground for scientific exploration and of substantial relevance for conservation. In North America and around the globe, long-distance migrants are declining more than other bird species. This pattern extends to shorebirds, most of which are declining and some of which have been recently listed under Species at Risk programs in Canada and the United States. A more complete understanding of seasonal interactions could better inform the management of these species by identifying the time periods and locations where conservation action is most urgently needed.