Stable isotope composition of faeces as an indicator of seasonal diet selection in wild herbivores in southern Africa
Faculty of Computing, Health and Science
School of Natural Sciences
We used stable carbon isotopes and nitrogen contents of faeces to investigate diet selection differences among wild grazers, browsers and mixed-feeders at seasonal intervals across a year in the Hluhluwe–Umfolozi Park, South Africa. Faecal 13C values showed that wildebeest and warthog selected predominantly C4 plant material throughout the year. Impala ingested significantly more C3 plant material during the winter months than in all other months. Nyala also ingested more browse during winter. The nitrogen content of wildebeest faeces was significantly lower in winter than in summer, suggesting a possible decline in diet quality during the dry winter months. No significant seasonal trend in faecal nitrogen content was evident for nyala or warthog. Nitrogen contents of impala faeces were significantly higher in spring than in other seasons. Faecal isotopic and nutrient content analyses appear to be useful indicators of short-term diet selection and nutritional status of free-ranging herbivores. Analyses show resource partitioning among the different herbivores at finer time resolutions than can be obtained from bone collagen or isotopic analysis of tooth enamel.