In the Central Karoo, small livestock losses to predators like jackals (Canis mesomelas) and caracals (Caracal caracal) are a chronic challenge to farmers and the leading cause of conflict with wildlife. Recently, farmers reported that chacma baboons (Papio ursinus) have added to their losses by targeting sheep. Here we use carbon and nitrogen isotopes ratio measured from hair of 33 baboons to assess whether animal protein constitutes a significant part of their diet. We then investigated variations in chronological values of stable isotopes in relation to seasonal variations in food sources using sequential analysis. The δ¹³C and δ¹⁵N results confirmed baboons largely vegetarian diet. Baboons mostly fed on C3 plants accessible near riverbeds. Invertebrates and C4 plants, including maize used by farmers to supplement the sheep, both contributed to a smaller portion of their diet. δ¹⁵N values were higher for males than females, but remained very low in comparison to livestock δ¹⁵N values. Only one individual showed significantly higher δ¹⁵N values over time. Sequential analysis revealed marked seasonal variations for both carbon and nitrogen, strikingly homogenous among individuals. Variations in δ¹⁵N values were likely related to short availability of preferred legume species following rain events. While the recurrence of drought events may have driven baboons toward alternative food sources when natural resources are scarce, only few individuals are probably involved in livestock predation. In the light of climate change, we emphasize the need for alternative management methods and discuss the use of stable isotopes as a tool for conservation.