Presented by Jackson W. Kusack - Email: jkusack@uwo.ca
Conservation and management of waterfowl requires accurate information on migratory connectivity between breeding and harvest areas. The international adaptive harvest management strategy between Canada and the US for the American Black Duck (Anas rubripes) uses information from harvested and banded individuals and assumes that they originate from the same geographic extent, although growing evidence suggests that this may not be the case. The northern part of the black duck breeding range in the boreal is not sampled by banding, making banding data biased to the southern portion of the breeding range. By contrast, individuals harvested in at least some regions are known to originate from throughout the boreal region. There are also differences in the adjusted age ratios that go into the strategy based on banding and harvest data when calculated only for Canada or only for the US, which may further suggest differences in the spatial extent of the origin of banded compared to harvested individuals among the two countries. Our objective was to utilize ratios of naturally-occurring stable isotopes (2H) within wing feathers to determine probabilistic origin of American Black Ducks harvested within black duck conservation regions located throughout Canada and the US. Feathers were collected from wings submitted by hunters to the species composition and parts collection surveys (2016 2019). Probabilistic origin was determined using likelihood-based assignment algorithms based on a predicted feather 2H isoscape. Using this information, we tested how origin of harvested individuals varies with (i) age (adults and hatch-years), (ii) sex, (iii) timing of harvest, and (v) conservation region. To further refine assignment of origin, additional priors (e.g., breeding density) and additional stable isotopes (13C, 15N) will be employed. Results from our integrative approach will be useful for evaluating and potentially improving the adaptive harvest management strategy.P.2-11: Origins of harvested American Black Ducks: a stable isotope approach
Jackson W. Kusack, Western University, London, Ontario
Douglas C. Tozer, Long Point Waterfowl and Wetlands Research Program, Bird Studies Canada, Port Rowan, Ontario
Keith A. Hobson, Western University, London, Ontario
Douglas C. Tozer, Long Point Waterfowl and Wetlands Research Program, Bird Studies Canada, Port Rowan, Ontario
Keith A. Hobson, Western University, London, Ontario