Nutritional Ecology of Brown Bears on the Coast of Katmai National Park

Project ID: P15AC00632

Federal Agency: National Park Service

Partner Institution: Washington State University

Fiscal Year: 2015

Initial Funding: $32,000

Total Funding: $32,000

Project Type: Research

Project Disciplines: Biological

National Park: Katmai National Park and Preserve

Principal Investigator: Robbins, Charles

Agreement Technical Representative: Adema, Guy

Abstract: Nutritional resources drive brown bear survival, productivity, and population density. Abundance, availability, quality, and seasonality are all factors influencing energetic and protein economies of bears. While bears gain significant weight in fall to support costs of hibernation and cub production, spring is also critical for female bears to support the additional costs of lactation and cub rearing. Marine intertidal invertebrates (MII), including clams, mussels, and barnacles, have been shown to be consumed by, and potentially important to, brown bears in spring in coastal southwest Alaska because of their high relative nutritive value compared to alternative resources. Thus, abundance and distribution of MII is likely an important driver of bear use of coastal and intertidal areas. The presence of bears attracts visitors to these areas for viewing and photography. While this is a highly desirable experience for visitors, it has potential to constrain access of bears to important forage resources if the presence of humans reduces their use. Thus, bear population health, bear use of intertidal areas, and the opportunity for humans to view bears in the spring and early summer may all be dependent on status of MII. This is a collaborative project between the National Park Service and Washington State University to evaluate brown bear reliance on these forage resources by assessing seasonal dietary composition (terrestrial vs. marine) using stable isotope analyses and determining seasonal body mass and composition of bears. The evaluation will include linking the relative proportion of MII compared to other food items in spring and summer bear diets to their body mass dynamics and energetics. Expected products include educational outreach materials and a manuscript to be submitted to a peer reviewed journal that describes the importance of marine intertidal invertebrates as nutritional resources to brown bears along the Katmai coast and how human presence may affect bear access to these valuables resources.