Will tree euphorbias (Euphorbia tetragona and Euphorbia triangularis) survive under the impact of black rhinoceros (Bicornis diceros minor) browsing in the Great Fish River Reserve, South Africa?

Abstract

The impact of black rhinoceros (Bicornis diceros minor) on the tree euphorbias Euphorbia tetragona and Euphorbia triangularis was studied in the Great Fish River Reserve, South Africa. Black rhinoceros pushed over about 5–7% of the trees in a 2‐month period. There was a preference of rhinos for smaller trees, however this preference did not guarantee euphorbia survival in the larger size classes. This means that tree euphorbias could very well disappear from all areas accessible to rhinos. Rhino feeding choices were correlated with higher plant moisture content, higher nitrogen content, and a higher digestibility.

A comparison of faecal analysis with backtracking to determine the diet composition and species preference of the black rhinoceros (Diceros bicornis minor)

“…The reserve lies within the thicket biome of the Eastern Cape Province (Cowling et al 2005) and is considered to be a good habitat for the black rhinoceros (Lent and Fike 2003), as evidenced by the rapid increase of the population (Heilmann et al 2006). The fieldwork was, for logistical reasons, concentrated on the western side of the Great Fish River, the area with the highest rhino density.…”

Impact of the black rhinoceros (Diceros bicornis minor) on a local population of Euphorbia bothae in the Great Fish River Reserve, South Africa

“…, 2003; Ganqa, Scogings & Raats, 2005). As has been suggested for other species of Euphorbia , E. bothae may also be a seasonally important source of water for the rhinos (Dudley, 1997; Heilmann et al. , 2006).…”

“…Black rhinos destroy Euphorbia tetragona and Euphorbia triangularis Desf. trees by pushing them over to feed upon the tips of the branches (Heilmann et al. , 2006).…”

“…Several scenarios for plant–herbivore interactions are known from the literature. The worst‐case scenario is a predator–prey interaction where the animals kill plants during one feeding event (Heilmann et al. , 2006).…”

The anomalous Kentucky coffeetree: megafaunal fruit sinking to extinction?

“…This hypothesis is entirely consistent with TiVney's (2004) interpretation that megafaunal dispersal is a diVuse process. Elephants (Loxodonta africana Blumenbach) readily eat and disperse some fruits that are not eaten by other animals (Gautier-Hion et al 1985;Dudley 2000), and black rhinoceros in southern Africa often consume the fruits and stems of highly toxic Euphorbia species that are avoided by other animals (Heilmann et al 2006;see Kinghorn 1979). A variety of large non-elephantine mammals may have had similar capacities, followed by mastodont-and mammoth-sized herbivores.…”