Evaluation of a Dual-frame Design to Estimate Occupancy and Productivity of Bald Eagle Nests in Kenai Fjords National Park

Bald eagles (Haliaeetus leucocephalus) are keystone predators on avian (e.g., seabirds) and fish (e.g., salmon) populations and hence serve an important ecological role in freshwater and marine coastal systems in national parks within the Southwest Alaska Network (SWAN; Figure 1) of the National Park Service (NPS). Three of these parks, Katmai National Park and Preserve (KATM), Kenai Fjords National Park (KEFJ), and Lake Clark National Park and Preserve (LACL), contain large breeding populations of bald eagles. Nonetheless, bald eagle populations in general are under continuing threat from human-related impacts such as ecotourism, sport and commercial fishing, timber harvest, potential mining activities adjacent to the parks, and potential oil spills or other accidents along marine coastlines (Buehler 2000). Further, global climate change will have an unknown effect on their forage base and nesting habitat (e.g., see Agler et al. 1999). Consequently, bald eagles were selected as a vital sign to monitor in SWAN parks and this vital sign was rated as highly desirable in the prioritization process (Bennett et al. 2006).