A comparison of woody browse selection by hand-raised, boma-adapted and wild black rhinoceros, <i>Diceros bicornis,</i> L. in Matusadona National Park, Zimbabwe

Abstract

. Boma-adapted rhinoceros were animals that were subjected to hand-raising and were kept in bomas (enclosures) over night. The feeding behaviour was different between the three rhinoceros groups. All rhinoceros groups utilised and selected for a few browse species in common, at different preference levels in the same habitat types according to season. Wild rhinoceroses browsed most in Colophospermum-Terminalia-Combretum woodland in the wet season and in thicket in the dry season. Hand-raised rhinoceroses browsed most in Colophospermum-Terminalia-Combretum woodland and boma-adated rhinos in thickets in both the wet and the early dry seasons. Hand-raised and bomaadapted rhinos changed their habitats less for browse selection than wild rhinos. This can be ascribed to a relative restriction of home range in the hand-raised group and a herding effect for the boma-adapted animals. These situations might have accounted for differences in seasonal browse selection by the rhinoceros groups.

Assessment of Browse Availability and Suitability for Black Rhino’s Re-Introduction in Northern Gonarezhou National Park, Southeastern Zimbabwe

“…Measured variables were tested for differences between the study strata using the two tailed Student t-test. Black rhino's principal browse frequency of occurrence and proportional quality of woody species was categorized and analyzed following a standard procedure by [20]. Browse quality ranking was conducted in combination with the knowledge on the woody species' value to potential black rhino diet following [21] known forage data as reference.…”

“…The browse suitability/electivity index was calculated after [21], from the equation E i . Principal woody species were defined as those that comprised ≥ 5% of the total number of bites made by the black rhino as earlier reported elsewhere in Matusadonha National Park, northern Zimbabwe [20] and [21]. Preferred woody species were determined using the browse suitability/electivity index described above and in [22].…”

“…Preferred woody species were determined using the browse suitability/electivity index described above and in [22]. Following several studies [20] [21] [22], those taxa with browse suitability/electivity indexes greater than 0.4 and comprising at least 1% of total measured diet are reported and discussed in this present study.…”

“…Spirostachys, Dichrostachys and Acacia genera which are known palatable quality browse suitable for black rhino's feed [20] [21] were recorded with high frequency occurrence within the northern side of the Runde River study stratum, suggesting it to be a more suitable sanctuary space for the proposed re-introduction of black rhinos in northern GNP. Earlier studies in GNP confirmed abundance of Spirostachys woodlands [31] and Acacia woodlands [24] within northern GNP.…”

“…Consistent with other studies, we recorded woody species of the following genera, the African bush willow (Combretum), mallow-leaved cross-berry (Grewia), bush guarri (Euclea), small-fruited potato bush (Phyllanthus), apple-ring acacia (Faidherbia), and chaste tree (Vitex), which are important food sources/forage for black rhinos in southern Africa [32] [33]. The woody plant genera that rank high in the diet of black rhinos in Zimbabwe are diverse, namely, Acacia, Aloe, Bauhinia, Combretum, Commiphora, Cordia, Croton, Diospyros, Diplorhynchus, Euphorbia, Grewia, Vitex and the fallen fruits of Kigelia africana [20] [34]. It was a positive finding that most of these woody species were recorded in northern GNP during the present study, over and above other recorded habitat forage status suggesting north of the Runde River as the most appropriate sanctuary of the proposed IPZ for black rhino re-introduction.…”