ROTH, J.D.*; WIESEL, I.; DREA, C.M.; University of Central Florida; Brown Hyena Research Project, Namibia; Duke University: Variation in seal consumption by brown hyenas in the Namib desert estimated using stable isotopes

Coastal areas often receive substantial inputs of energy and nutrients from the ocean, and these allochthonous inputs can be important for terrestrial consumers. The Namib desert is a hyper-arid desert with very low primary productivity, but the highly productive ocean along the coast of southwestern Africa supports large, permanent colonies of seabirds and seals that can be an important food source for terrestrial consumers. We used stable isotope analysis to reconstruct the diet of brown hyenas (Hyaena brunnea) along the coast of the Namib desert, where the primary prey available are Cape fur seals (Arctocephalus pusillus). Stable-nitrogen and carbon isotope ratios of hyena hair were compared with samples collected from seals and other prey species. Hyena diets were influenced by proximity to seal colonies, with decreasing stable-nitrogen and carbon isotope ratios as distance from colonies and from the ocean increased. Age class also affected diet, with older hyenas consuming a greater proportion of marine-based foods. Since desert soils are so nutrient-poor, the nutrient additions from allochthonous marine inputs transported by brown hyenas could be an important resource for the desert ecosystem.