Habitat use and diet selection of reintroduced white rhinoceros (Ceratotherium simum) in Pafuri, Kruger National Park

[摘要] ENGLISH ABSTRACT: In 2005, six white rhinoceros (Ceratotherium simum) were reintroduced into Pafuri, inthe far northern section of Kruger National Park (KNP), South Africa, as part of alarge mammal reintroduction project. All six individuals were fitted with horn radiotransmitters. Rhinos have been absent from Pafuri for over a century, and this projectaimed to establish a breeding nucleus in the area. The aim of this study was tomonitor post-release movement and habitat use of these animals within the 203 km2study area and assess the short term success of the re-introduction project as well asthe suitability of the five landscape types in Pafuri as a habitat for white rhinoceros.Habitat suitability and selection was assessed at two ecological hierarchical scales: 1)landscape system, analysed further down to the spatial scale of range and territoryestablishment, and 2) feeding station for diet selection. Rhinos were tracked for 12months and a database of 719 sighting records was compiled. These data were used todetermine the utilisation of and preference between the Pafuri landscape types, usingpreference indices that compare utilisation versus availability. An a-LoCoHnonparametric kernel method was used to calculate home ranges and utilisationdistributions of each rhino. Feeding surveys were attempted by backtracking alongfresh rhino feeding paths and recording the grass species present and eaten in 0.7 m x0.7 m quadrats. Faecal samples were collected and analysed using microhistologicaltechniques and dietary composition was assessed for each rhino.Landscape preference analyses showed that the rhinos favoured Colophospermummopane Shrubveld on calcrete in the dry season, and the Punda Maria Sandveld in thewet season. The territory establishment of the dominant bull was substantially larger(44.8 km²) than those of adult male rhinos in the rest of KNP. Ranging areas of themature females (17 – 25.4 km²), were consistent with sizes of previous studies. Thetwo sub-adults ranged far more extensively, establishing an 84.1 km² annual rangeduring the study period. The annual diet consisted of mostly perennial grass species,with moderate grazing value species dominating for most of the year. Dietaryanalyses showed that Schmidtia pappophoroides, Eragrostis superba, Enneapogon cenchroides,Cenchrus ciliaris and Stipagrostis uniplumis were the primary grass species consumed.viiThis study demonstrated that the Pafuri rhinos are behaving similarly to rhinosestablished in other areas, with movements around the landscapes being primarilyinfluenced by rainfall and permanent water sources, and the high quality grazing thatis more abundant in the wet season. Their range and territory sizes were inevitablylarge, for a low density area, but not uncommonly so. The most significant outcomeof this study was the preference shown for the Colophospermum mopane Shrubveld oncalcrete landscape that is classed as unique within South Africa, and was also rankedas 'avoided' by the earlier KNP studies into landscape preferences of rhinos. Thegrass cover in Pafuri, although sparse and very dry, contained a diversity of low tohigh grazing value grasses that the rhinos appeared to exploit to the best of theirability. The abundance of moderate grazing value species in their diets, and the lownumber of low grazing value species suggests that they are maximising theopportunities to graze on nutritious grasses when they are available. Our findingssuggest that the Pafuri area is suitable for the establishment of a small breedingnucleus of white rhinos. The abundance of permanent water, in the form of springs,is a great advantage however, the potential for bush encroachment into grasslands inareas of such low rainfall needs to be considered if the population continues to growat the current rate. The birth of two new calves in 2008 confirms that these rhinoshave settled and adapted to their new habitat, and is a very promising sign for thefuture of this increasing subpopulation.

[发布机构] Stellenbosch University