Effects of Mean Annual Precipitation and Temperature on Carbon and Nitrogen Isotopes in Neighboring Chimpanzee Sites Within Gombe and Ugalla National Parks

Diet inuences carbon and nitrogen stable isotope ratios (δ 13 C and δ 15 N values) in animal tissues; and here we explore the inuences of the local ecology on those values in six separate troops of chimpanzees (Pan troglodytes). In this study we build upon Schoeninger et al.’s 2016 paper by exploring the inuence of environmental factors by comparing three separate chimpanzee sites within Gombe Park to another three sepa- rate sites in neighboring Ugalla Park. We present new δ 13 C and δ 15 N values by using hairs collectedfrom night nests in the 90’s and early 2000’s from Gombe and Ugalla. We then compare these new chimpanzee δ 13 Chair and δ 15 Nhair values to local Mean Annual Precipitation (MAP), Mean Annual Temperature (MAT), and the relationship between MAP and MAT. We used these compari- sons to test hypotheses based on known effects of these variables on the δ 13 C and δ 15 N values in plant tissues that may be consumed by the chimpanzees. The comparisons show that hair from chimpanzees living in sites with lower MAP have higher δ 13 Chair and δ 15 Nhair values than do chimpanzees living in sites with higher MAP. Neither δ 13 Chair or δ 15 Nhair were signicantly related to MAT, however, the relationship between MAP and MAT was seen to be signicant. These results suggest the potential of using δ 13 C and δ 15 N values in primate tissues to infer attributes of their local ecology in circumstances where ecology may be unknown, such as samples collected in the last few hundred years or fossil hominin