Cooperative Fish and Wildlife Research Units Program: Headquarters
Education, Research and Technical Assistance for Managing Our Natural Resources

The U.S. Fish and Wildlife Service is tasked with setting objectives and measurable criteria for delisting species or populations listed under the Endangered Species Act. Determining the acceptable threshold for extinction risk for any species or population is a challenging task, particularly when facing marked uncertainty. The Alaskan breeding population of Steller’s Eiders (Polysticta stelleri) was listed as threatened under the Endangered Species Act in 1997 due to a perceived decline in abundance and nesting range and geographic isolation from the Russian breeding population. However, previous genetic studies and modeling efforts suggest that there may be dispersal from the Russian breeding population. Additionally, there is evidence of population level non-breeding events. This research is aimed to estimate population viability of the Alaskan breeding population of Steller’s eiders using both an open and closed model of population process for this threatened population. Projections suggest under a closed model of population process this population has a 100% probability of extinction within 42 years. Projections from the open population model suggest that with immigration there is no probability of permanent extinction. However, due to random immigration process and non-breeding behavior it is likely that this population will continue to be present in low and highly variable numbers on the breeding grounds in Alaska. Monitoring the winter population, which contains both Russian and Alaskan breeding birds, may offer a more comprehensive indication of population viability.