The Yukon–Kuskokwim Delta of Alaska,USAis a globally important region for numerous avianspecies including millions of migrating and nesting waterbirds.However, data on the current spatial distributionof critical nesting areas and the importance of environmental variables in the selection of nest locations aregenerally lacking for waterbirds in this region.We modeled nest densities for 6 species of geese and eiders thatcommonly breed on the Yukon–Kuskokwim Delta, including cackling goose (Branta hutchinsii minima),emperor goose (Chen canagica), black brant (B. bernicla nigricans), greater white-fronted goose (Anser albifronsfrontalis), spectacled eider (Somateria fischeri), and common eider (S. mollissima).Thedata used were fromsinglevisitnest searches on 2,318 plots sampled during 29 years from1985 to 2013.Wemodeled nest density for eachspecies by combining data across years and using random forests methods and time-static landscapeenvironmental variables. These models provide the first habitat-specific predictive distributions of nest densityfor these species breeding on the Yukon–Kuskokwim Delta of Alaska. Predictive performance of the randomforests models varied among species, explaining 13–69% of the variance in nest density. For most species, nestdensity was greatest near the coast and within lowland habitats. Predicted nest densities mapped across thecoastal zone of the Yukon–Kuskokwim Delta revealed areas of high and low nest densities that can be used toinform management and conservation decisions.
