Utilization of woody browse and habitat by the black rhino (Diceros bicornis)in western Itala Game Reserve

Abstract

Black rhinoceros browse utilization was assessed at the woody plant species and community levels in western Itala Game Reserve, South Africa, using a semi-quantitative, plant-based method. Theis knowledge was used to hypothesize the possible effects of vegetation change on the black rhinoceros (Diceros bicornis). Acacia nilotica, Acacia karroo, and Dichrostachys cinerea contributed most to the diet, and Cassine transvaalensis, Rhus guenzii, and Acacia gerrardii were the most preferred species. Eightysix percent of the recorded browse was from plants <2.5 m, suggesting that a change from open woodland, with many trees, to a closed woodland, with a few small trees, would disadvantage black rhino. Plant communities ranged from highly utilized (bottomland scrub forest) to unutilized (Combretum apiculatum sparse woodland). The extremely patchy distribution of browse utilization within communities suggests that there are other important factors affecting browse utilization besides plant species composition. It appears that tall grass detracts from browse value, while factors that improve access, such as gentle slopes and paths, enhance habitat suitability. It is hypothesized that forest verges provide important black rhino feeding areas.

The influence of dietary tannin supplementation on digestive performance in captive black rhinoceros (Diceros bicornis)

“…African browse consumed by giraffe (Giraffa camelopardalis) for condensed tannin (CT) content; many plant species investigated in that study have also been reported to be eaten by the black rhinoceros (Joubert and Eloff, 1971;Ghebremeskel et al, 1991;Kotze and Zacharias, 1993;Atkinson, 1995;Dierenfeld et al, 1995), and invariably contained tannins. Quantified tannin levels in plants consumed by freeranging black rhinoceros are summarized in Table 1.…”

“…Several authors have demonstrated the presence of tannins in natural forage consumed by free‐ranging black rhinoceros (Loutit et al., 1987; Atkinson, 1995; Wright, 1998; Muya and Oguge, 2000). Furstenburg and van Hoven (1994) analysed African browse consumed by giraffe ( Giraffa camelopardalis ) for condensed tannin (CT) content; many plant species investigated in that study have also been reported to be eaten by the black rhinoceros (Joubert and Eloff, 1971; Ghebremeskel et al., 1991; Kotze and Zacharias, 1993; Atkinson, 1995; Dierenfeld et al., 1995), and invariably contained tannins. Quantified tannin levels in plants consumed by free‐ranging black rhinoceros are summarized in Table 1.…”

Forage quality, twig diameter, and growth habit of woody plants browsed by black rhinoceros in semi-arid subtropical thicket, South Africa

“…Like other mammal herbivores, black rhinos are known also to compile their diets according to various characteristics of plants and plant parts (Ganqa et al, 2005;Muya and Oguge, 2000;Oloo et al, 1994;). For browsers that ingest much of their diet by biting twigs (including leaves), such as black rhino, variations in forage quality among twigs of different diameters are likely to be important in determining their foraging efficiency (e.g., rate of energy intake) and therefore their reproductive success (Kotze and Zacharias, 1993;Shipley et al, 1999). This is because correlations between forage quality and twig size compel browsers to compromise between nutrient intake and dry matter intake (Shipley et al, 1999).…”

Dry Season Browse Preference for the Black Rhinoceros (Diceros bicornis): The Case of the Midlands Black Rhino Conservancy (MBRC), Zimbabwe

“…Acacia species were principal and preferred food plants in Karoo and Valbos National Parks, South Africa (Buk and Knight, 2010). Acacia species were also important black rhino food plants in Itala-South Africa, Masai Mara-Kenya, and NairobiKenya (Kotze and Zacharias, 1993;Mukinya, 1977;Muya and Oguge, 2000). There were slight differences although not significant in the species composition of the black rhino diet in the MBRC between the early dry and late dry seasons.…”

“…Although little is known about the minimum habitat that can be managed effectively to sustain a viable rhino population, food availability and quality are major factors that determine habitat suitability. For large browsers such as black rhinoceros that ingest much of their diet by biting twigs (Kotze et al, 1993), variations in physical and chemical characteristics among twigs of different diameter are likely to be important in determining foraging efficiency, and therefore reproductive success (Shipley et al, 1999).…”