Inter‐ and intrahabitat dietary variability of chacma baboons (Papio ursinus) in South African savannas based on fecal δ¹³C, δ¹⁵N, and %N

Abstract

Baboons are dietary generalists, consuming a wide range of food items in varying proportions. It is thus difficult to quantify and explain the dietary behavior of these primates. We present stable carbon (delta(13)C) and nitrogen (delta(15)N) isotopic data, and percentage nitrogen (%N), of feces from chacma baboons (Papio ursinus) living in two savanna environments of South Africa: the mountainous Waterberg region and the low-lying Kruger National Park. Baboons living in the more homogeneous landscapes of the Waterberg consume a more isotopically heterogeneous diet than their counterparts living in Kruger Park. Grasses and other C(4)-based foods comprise between approximately 10-20% (on average) of the bulk diet of Kruger Park baboons. Carbon isotopic data from the Waterberg suggest diets of approximately 30-50% grass, which is higher than generally reported for baboons across the African savanna. Based on observations of succulent-feeding, we propose that baboons in the Waterberg consume a mix of C(4) grasses and CAM-photosynthesizing succulents in combined proportions varying between approximately 5-75% (average, approximately 35%). Fecal delta(15)N of baboons is lower than that of sympatric ungulates, which may be due to a combination of low levels of faunivory, foraging on subterranean plant parts, or the use of human foods in the case of Kruger Park populations. Fecal N levels in baboons are consistently higher than those of sympatric ungulate herbivores, indicating that baboons consume a greater proportion of protein-rich foods than do other savanna mammals. These data suggest that chacma baboons adapt their dietary behavior so as to maximize protein intake, regardless of their environment.

Stable isotope-based diet reconstructions of Turkana Basin hominins

“…Baboons have been suggested as an important study analog for early hominins (59,60); thus future studies of baboon diets, coupled with stable isotope analyses, will be a fruitful avenue of research.…”

What Insights Can Baboon Feeding Ecology Provide for Early Hominin Niche Differentiation?

“…A third photosynthetic pathway, crassulacean acid metabolism (CAM), most common among succulents, has δ 13 C values that may be intermediate between the 2 end points, or may be indistinguishable from C 3 or C 4 plants, depending on whether they are obligate CAM-photosynthesizers or capable of switching between C 3 , C 4 , and CAM (Keeley and Rundel 2003). In our study areas, i.e., southern African subtropical savanna habitats, most CAM plants have a C 4 carbon isotopic signature (Codron et al 2006). Therefore, the δ 13 C of herbivores feeding here reflect proportions of C 3 to C 4 /CAM biomass consumed.…”

“…By contrast, carbon isotope data from both fossil and extant baboons (Papio spp., Parapapio spp., and Theropithecus spp.) implies that all consumed some C 4 foods, in varying proportions that may be similar to that of the early hominin specimens (Codron et al 2005a(Codron et al , 2006LeeThorp et al 1989a;Thackeray et al 1996).…”

“…We aimed to explore analogies between the ecology of baboons with hominins. We combine new and previously published (Codron et al 2006; feces only) stable isotope data from feces, hair, and tooth dentine collagen specimens of chacma baboons (Papio ursinus) from several savanna habitats in South Africa to assess the magnitude of variation in their diets and the habitat types that favor C 4 consumption. We then use this information to raise possibilities for early hominin ecology, and test the predictions by comparing carbon isotope trends in baboons with the ones reported for early hominins.…”

A reconstruction of the Vienna skull of Hadropithecus stenognathus

“…Exceptionally high ␦ 15 N values (9) may suggest a preference for CAM over C4 plants, however. Codron et al (21,22) The degree to which heavy microwear pitting reflects high exogenous grit as opposed to the consumption of hard foods per se will also require further exploration (9); the dental microstructure of Hadropithecus is better suited to resist tough foods than to resist hard foods (see ref. 24).…”