Diet preference of black rhinoceros Diceros bicornis at Welgevonden Game Reserve, South Africa, across seasons

Abstract

Diet preference of the black rhinoceros Diceros bicornis was determined in Welgevonden Game Reserve (WGR), located in the Waterberg region of Limpopo Province, South Africa. Fieldwork was conducted in the dry, early wet and late wet seasons. Diet preference was determined using microhistological faecal analysis and browse availability surveys. A chi-square goodness-of-fit test assessed similarity between the observed diet composition based on dung samples and the expected diet composition. To account for potential non-independence between browse availability and diet composition, a weighted approach was employed where browse availability was just one of several contributing factors to the expected composition. Plant species selectivity was quantified by Ivlev’s electivity index. Results obtained from this indicated that these black rhinos preferentially browsed certain plant species across different seasons. Plant species observations in the dung samples from the dry season totalled 3 984, with the evergreen Natal gum Euclea natalensis dominating the diet; for the early wet season, plant observations in the dung totalled 1 479, with buffalo thorn Ziziphus mucronata dominating in the diet; for the late wet season, plant observations in the dung totalled 4 424, with the small deciduous tree Ochna pulchra dominating in the diet. By obtaining information on food selection and the availability of browse species across seasons, this study provides a clearer understanding of black rhinos’ forage preference in WGR.