Predicting waterbird nest distributions on the Yukon-Kuskokwim Delta of Alaska

The Yukon–Kuskokwim Delta of Alaska, USA is a globally important region for numerous avian species including millions of migrating and nesting waterbirds. However, data on the current spatial distribution of critical nesting areas and the importance of environmental variables in the selection of nest locations are generally lacking for waterbirds in this region. We modeled nest densities for 6 species of geese and eiders that commonly 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 albifrons frontalis), spectacled eider (Somateria fischeri), and common eider (S. mollissima). The data used were from single-visit nest searches on 2,318 plots sampled during 29 years from 1985 to 2013. We modeled nest density for each species by combining data across years and using random forests methods and time-static landscape environmental variables. These models provide the first habitat-specific predictive distributions of nest density for these species breeding on the Yukon–Kuskokwim Delta of Alaska. Predictive performance of the random forests models varied among species, explaining 13–69% of the variance in nest density. For most species, nest density was greatest near the coast and within lowland habitats. Predicted nest densities mapped across the coastal zone of the Yukon–Kuskokwim Delta revealed areas of high and low nest densities that can be used to inform management and conservation decisions. © 2017 The Wildlife Society.