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

Abstract

Wildlife reintroduction regulations require feasibility assessment to inform planning. The study aims to contribute to the existing knowledge on northern Gonarezhou National Park (GNP), southeastern Zimbabwe, prior to the black rhino re-introduction project. The study objective was to assess browse availability and suitability for black rhino re-introduction in northern GNP.We stratified the study area into two strata, i.e. north and south of Runde River in GNP. A total of 96 sample plots measuring 20 m × 30 m (i.e., 48 plots in each study stratum) were randomly placed across the study strata, between March and April 2011. Woody plant variables recorded are: shrub height, shrub canopy diameters, evidence of browsing on woody plants, number of shrubs and woody species. Principal browse frequency of occurrence and proportional quality of woody species were categorized and analyzed in combination with knowledge on the woody species' value to black rhino diet. Preferred woody species were determined using browse suitability/electivity index. A total of 3201 woody plants were recorded across the study strata. Woody species diversity and black rhino's browse suitability/electivity value significantly (p = 0.001) differed across the study strata. However, there were no significant differences in shrub density, shrub canopy volume and density of browsed plants. Common principal forages were recorded and included: knob thorn Acacia (Acacia nigrescens), small-leaved sickle-bush (Dichrostachys cineria) and tamboti (Spirostachys africana). The study suggested that black

Does variation in plant diversity and abundance influence browsing intensity in black rhinos?

“…Analysis of forage edible in fourteen rhino range areas shows that species belongs to genera Barleria, Commiphora, Euclea, Maerua, Solanum, and Ziziphus are mostly consumed during wet seasons while Balanites, Caesalpinia and Euphorbia are mostly consumed during the dry seasons. Also, species of Acacia, Grewia, Azima, Dichrostachys, Indigofera and Plumbago genera are consumed throughout the year irrespective of seasonality (Buk & Knight, 2010; Ganqa et al, 2005; Goddard, 1970; Goza et al, 2019; Gyöngyi & Elmeros, 2017; Kotze & Zacharias, 1993; Makaure & Makaka, 2013; Muya & Oguge, 2000; Oloo et al, 1994). Similarly, black rhinos in MRS consume forages belonging to the same genera in both seasons.…”

“…A Global Positioning System (GPS) receiver was used to locate each sampling plot on the survey grids (Mikulyuk et al, 2010). We used field observation method (Goddard, 1970; Goza et al, 2019; Kotze & Zacharias, 1993; Muya & Oguge, 2000) to study total plant species available and those foraged by black rhinos in MRS. We further used indirect observation technique to identify and collect data on plant species browsed by rhinos (Hall‐Martin et al, 1982; Oloo et al, 1994) due to presence of thick vegetation cover in some areas limiting direct observation of browsing rhinos. Freshly browsed trees, shrubs and herbs with a maximum canopy and branches height of 2 m were identified and recorded based on the browse characteristics of scissor‐like oblique clips on the cut surface of shoots and twigs by black rhinos as described by Kotze and Zacharias (1993).…”

“…A Global Positioning System (GPS) receiver was used to locate each sampling plot on the survey grids (Mikulyuk et al, 2010). We used field observation method (Goddard, 1970;Goza et al, 2019;Kotze & Zacharias, 1993;Muya & Oguge, 2000) to study total plant species available and those foraged by black rhinos in MRS. We further used indirect observation technique to identify and collect data on plant species browsed by rhinos (Hall-Martin et al, 1982;Oloo et al, 1994) due to presence of thick vegetation cover in some areas limiting direct observation of browsing rhinos.…”

“…Studies of black rhino dietary assessment have largely been carried out by indirect observation method (Goza et al, 2019;Hall-Martin et al, 1982;Kotze & Zacharias, 1993;Muya & Oguge, 2000), direct observation or backtracking of the browsing path of mega-herbivores (Anderson et al, 2020;Emslie & Adcock, 1994;Ganqa et al, 2005;Goddard, 1968;Mukinya, 1977;Muya & Oguge, 2000) and faecal analysis technique (Anderson et al, 2020;Hall-Martin et al, 1982;Van Lieverloo et al, 2009) reserve with an area of approximately 3245 km 2 . MRS was established in 1997 purposely for breeding black rhinos and later restocking areas that previously had black rhinos within Tanzania.…”

“…Studies of black rhino dietary assessment have largely been carried out by indirect observation method (Goza et al, 2019; Hall‐Martin et al, 1982; Kotze & Zacharias, 1993; Muya & Oguge, 2000), direct observation or backtracking of the browsing path of mega‐herbivores (Anderson et al, 2020; Emslie & Adcock, 1994; Ganqa et al, 2005; Goddard, 1968; Mukinya, 1977; Muya & Oguge, 2000) and faecal analysis technique (Anderson et al, 2020; Hall‐Martin et al, 1982; Van Lieverloo et al, 2009) or both. Here we used indirect method to identifying forage species eaten by rhinos as an indirect indicator of its diet and compared results with literature data on rhino feeding from fourteen rhino range areas in Africa savannah to ascertain forage species consumed by rhinos in wet and dry seasons in MRS.…”