Tuesday, August 4, 2009 - 8:40 AM

COS 17-3: Sharing the ecological pie: Community-level differences in prey specialization among African carnivores throughout the 20th century

Justin D. Yeakel, Paul L Koch, and Nathaniel J Dominy. University of California, Santa Cruz

Background/Question/Methods African ecosystems are distinguished by relatively large numbers of co-occurring carnivores. Because behavioral interactions between carnivores are difficult to quantify, there exists uncertainty as to how these relationships affect food-web structure and stability across a range of habitats and throughout extended periods of time. Stable isotope ratios record aspects of dietary input and are preserved in biological tissue. Accordingly, analysis of carbon and nitrogen isotope ratios of predators and potential prey in related systems is poised to elucidate aspects of large-scale carnivore community structure through space and time, thereby allowing comparative relationships between species to be analyzed quantitatively. Here we investigate competitive interactions among large-bodied carnivore species (lions, hyenas, and canids) within historical (1908-1911; from the Roosevelt/Rainey East African Expedition) and modern (1980-2000) sites that range from central to southwestern Kenya. Sampling was conducted in field and museum settings, while both hair and/or bone tissue from carnivores and potential prey were used in the analysis.

Results/Conclusions Our results reveal shifting community-level foraging strategies that suggest very different interaction dynamics between groups of sympatric carnivores throughout the 20th century. Our analysis of carbon and nitrogen isotope ratios of modern fauna indicate a high degree of prey specialization among species, while values from historical carnivores indicate a significant amount of foraging similarity. Differences in such community-level interactions are thought to have a profound impact on food-web dynamics. Future research will be directed towards assessing the fragility of these systems within the context of environmental and anthropogenic variables that are known to have influenced ecosystems in southern Kenya throughout the 20th century.