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H.2-3: An overview of isotopic methods and applications for estimating origins of migratory waterfowl

Presented by Douglas C. Tozer - Email: dtozer@birdscanada.org

Ratios of naturally-occurring stable isotopes (e.g., 2H, 13C, 15N, 18O, 34S) in bird tissues such as claws or feathers are now routinely sampled to estimate migratory connectivity in a variety of bird species including waterfowl. The method takes advantage of variation in the spatial distribution of stable isotopes in the environment that are, in turn, incorporated into bird tissues during tissue growth. Metabolically inert tissues are especially useful because they lock in isotopic values associated with origins of individuals, to be estimated when birds are captured and tissues are sampled at later times and often very distant locations. This comes as a huge advantage for estimating migratory connectivity given that birds only need to be captured or sampled once, unlike other methods, such as banding, that require initial and subsequent captures. However, like any method, using stable isotopes to estimate migratory connectivity comes with limitations that are important to understand. In this talk, we will 1) overview methods for using stable isotopes to estimate origins of sampled waterfowl, 2) discuss some applications that are especially suitable to the method, 3) outline important gaps in waterfowl knowledge that can be filled using the method, and 4) illustrate the usefulness of the method with preliminary findings from some of our recent sampling of stable isotopes in harvested individuals of multiple migratory duck species mainly in the Great Lakes region. During the talk, we will answer the question: are stable isotopes any good for estimating origins of migratory waterfowl? The answer is yes, but as we will show, the answer is yes only for suitable questions asked at appropriate scales.
Session: Movement & Tracking (Thursday, August 29, 13:20 to 15:00)