Interactions between migratory shorebirds and soft-sediment intertidal systems in Atlantic Canada

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Many species of North American shorebirds are experiencing population declines. Shorebirds that migrate long distances are vulnerable to habitat degradation throughout their range, including on migratory stopover sites. Preserving integrity of stopover sites is thus an important conservation objective, and appropriate habitat management is facilitated by a clear understanding of the structure and function of the ecosystems involved. Coastal areas of Atlantic Canada provide stopover sites for large populations of shorebirds migrating from the Arctic to southern wintering grounds in late summer and fall. The Bay of Fundy is a critical stopover area for Semipalmated Sandpipers. Considerable research has been done on use of the Bay by these birds, and on the ecological community associated with mudflats in the region. However, other coastal sites, such as in eastern New Brunswick and southern Nova Scotia, are also important to multiple species but have received much less attention. I propose to examine how shorebirds interact with and use these sites. Specifically, I will use radio-tracking technology to examine movements, habitat use and duration of stay of Semipalmated Sandpipers and Semipalmated Plovers. I will also examine behaviour of birds at sites and link that to habitat characteristics and availability of prey. I will conduct a broad-scale sampling study to assess site characteristics across the study area, and link those with abundance of shorebirds. Following identification of important sites, I will conduct manipulative experiments to assess the ecological interactions that structure communities at these sites. I will also investigate how use of different habitats affects sandpiper diets and fattening rates. To achieve this, I will collect blood samples from birds in the Bay of Fundy and at other coastal sites, and analyze plasma triglyceride levels (an indication of fattening rates) and stable isotope levels (a way to estimate diet). I will then radio-track birds in both areas to determine how long they remain in the region. Finally, following up on previous work in this area, I will conduct manipulative experiments on intertidal mudflats to help us to understand the effects of order of colonization on development of the mudflat community, and resulting prey availability for shorebirds. The work proposed here will enhance our understanding of shorebird use of migratory stopover sites in this region. It will allow us to test hypotheses about movement and duration of stay relative to diet and fattening rate, and will contribute to predictive models identifying key shorebird habitat. Canada hosts a large proportion of the population of both shorebird species I propose to study. As such, we have a significant responsibility their conservation. My work will contribute to this effort, providing some of the information necessary to make informed conservation decisions.