Abstracts

Presented by Bradley Fedy - Email: bfedy@uwaterloo.ca

The boreal forest is one of North Americas most important breeding areas for ducks, but knowledge of duck nesting ecology in the region is limited. We collected microhabitat data related to vegetation structure and composition at 157 duck nests and paired-random available locations from 2016 2018 in the western boreal forest (WBF) of Alberta, Canada. We identified fine scale microhabitat features selected by ducks for all species, nesting guilds, and 5 individual species using conditional logistic regression. Boreal ground nesting ducks selected nest sites that provided greater overhead and graminoid cover, but selected for less forb cover. Upland and overwater nesting guilds selected similar features, with the differentiation of selection of greater shrub cover and less lateral concealment by upland nesting species and selection for less shrub cover by overwater nesting species. We also estimated species-specific microhabitat nest-site selection for American Wigeon, Blue-winged Teal, Green-winged Teal, Mallard, and Ring-necked Duck. We observed variation in selection of vegetation composition among species, which may facilitate species coexistence at a regional scale. In addition to quantifying nest site selection, we also used our data to evaluate support for the nest concealment hypothesis. The nest concealment hypothesis assumes that birds select nest sites surrounded by dense vegetation to avoid detection by predators, because avian species are under intense selective pressure in choosing a safe nest site, where predation is the primary cause of nest failure. Our results suggest a tradeoff is made by upland nesting species, where females might balance the need for concealment from aerial predators with the need for increased vigilance and escape from terrestrial predators. Subsequent alteration in vegetation heterogeneity or predator communities in the boreal caused by climate and land use change may affect nest-site selection strategies used by boreal ducks. Therefore, we recommend further investigation of nest-site selection and survival at multiple spatial scales for boreal conservation and management.