The Potential Distributions, and Estimated Spatial Requirements And
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The potential distributions, and estimated spatial requirements and population sizes, of the medium to large-sized mammals in the planning domain of the Greater Addo Elephant National Park project A.F. BOSHOFF, G.I.H. KERLEY, R.M. COWLING and S.L. WILSON Boshoff, A.F., G.I.H. Kerley, R.M. Cowling and S.L. Wilson. 2002. The potential distri- butions, and estimated spatial requirements and population sizes, of the medium to large-sized mammals in the planning domain of the Greater Addo Elephant National Park project. Koedoe 45(2): 85–116. Pretoria. ISSN 0075-6458. The Greater Addo Elephant National Park project (GAENP) involves the establishment of a mega biodiversity reserve in the Eastern Cape, South Africa. Conservation planning in the GAENP planning domain requires systematic information on the potential distri- butions and estimated spatial requirements, and population sizes of the medium to large- sized mammals. The potential distribution of each species is based on a combination of literature survey, a review of their ecological requirements, and consultation with con- servation scientists and managers. Spatial requirements were estimated within 21 Mam- mal Habitat Classes derived from 43 Land Classes delineated by expert-based vegeta- tion and river mapping procedures. These estimates were derived from spreadsheet models based on forage availability estimates and the metabolic requirements of the respective mammal species, and that incorporate modifications of the agriculture-based Large Stock Unit approach. The potential population size of each species was calculat- ed by multiplying its density estimate with the area of suitable habitat. Population sizes were calculated for pristine, or near pristine, habitats alone, and then for these habitats together with potentially restorable habitats for two park planning domain scenarios. These data will enable (a) the measurement of the effectiveness of the GAENP in achieving predetermined demographic, genetic and evolutionary targets for mammals that can potentially occur in selected park sizes and configurations, (b) decisions regard- ing acquisition of additional land to achieve these targets to be informed, (c) the identi- fication of species for which targets can only be met through metapopulation manage- ment, (d) park managers to be guided regarding the re-introduction of appropriate species, and (e) the application of realistic stocking rates. Where possible, the model predictions were tested by comparison with empirical data, which in general corrobo- rated the predictions. All estimates should be considered as testable hypotheses. Key words: conservation planning, mammals, distribution, density, population esti- mates, Addo, South Africa. A.F. Boshoff, G.I.H. Kerley and S.L. Wilson, Terrestrial Ecology Research Unit, Depart- ment of Zoology, University of Port Elizabeth, Port Elizabeth, 6013, Republic of South Africa; R.M. Cowling, Terrestrial Ecology Research Unit, Department of Botany, Uni- versity of Port Elizabeth, Port Elizabeth, 6013, Republic of South Africa. Introduction “greater” Addo Elephant National Park In November 2000, the Global Environment (GAENP). The SW boundary of the Addo Facility (GEF) approved a grant to South Elephant National Park (AENP) is some African National Parks (SANParks) to 35 km east of the city of Port Elizabeth research and prepare a full proposal to the (33°58'S, 25°31'E), South Africa. The vision GEF for the planning and establishment of a for an expanded Addo Elephant National ISSN 0075-6458 85 Koedoe 45/2 (2002) Park was developed and documented by because it is likely that if their minimum area Kerley & Boshoff (1997, 2002, www.zoo. requirements are met, adequate survival con- upe.ac.za/teru). Systematic conservation ditions will be simultaneously met for other planning forms an integral and critical com- biota. In this regard, many of these mammals ponent of the implementation of the GAENP qualify as “umbrella” species (sensu Wilcox project, managed by South African National 1982) since their minimum area require- Parks (“http://www.addoelephantpark.com” ments are likely to be at least as comprehen- www.addoelephantpark.com). Note that the sive as those for the remainder of the com- original boundary of the proposed expansion munity. Mammals with a large body size to the AENP (Kerley & Boshoff 1997) has (e.g., some ungulates) or which occupy a been modified, by SANParks, for the pur- high trophic level (e.g., carnivores) are poses of the conservation planning exercise regarded as good candidates for target for GAENP, by the addition of a 5-km buffer species acting as “umbrella” species (Wilcox that follows cadastral boundaries. 1982). In addition, the distributions and spa- While the impressive plant diversity remains tial requirements/densities of the larger a major focus of conservation planning in the mammals are probably better known, or can establishment of a GAENP (Kerley & be better estimated, than those of the small- Boshoff 1997), other biota and ecological sized mammals in the GAENP planning processes which impact on the park’s biodi- domain. In any case, realistic data for these versity must be taken into account in two population parameters are essential for attempting to achieve its broad conservation any conservation exercise that deals with the objectives. The species’ patterns and ecolog- establishment and maintenance of minimum ical and evolutionary processes in the viable populations of the larger mammalian GAENP planning domain include the medi- fauna (Caughley 1994; Caughley & Sinclair 1994; Lande & Barrowclough 1987). um to large-sized mammals and the process- es that they drive, many of which (a) are in An additional consideration for determining need of conservation intervention, and (b) minimum area requirements for preserving may have an important impact on the park’s biological diversity is that of the estimation biota, at the species, community and ecosys- of minimum viable populations (MVP) for tem functioning levels. Herbivory is known “target” species (Wilcox 1982; Soulé 1987). to have an impact on the species composi- The MVP is a set of specifications concern- tion, structure and dynamics of fynbos vege- ing the size and structure of the populations tation (Campbell 1986; Johnson 1992) and of a species that is necessary to provide a thicket vegetation (Barratt & Hall-Martin margin of safety from extinction. The MVP 1991; Johnson et al. 1999; Lombard et al. for a species can be translated into the mini- 2001; Moolman & Cowling 1994; Penzhorn mum area requirements by determining the et al. 1974; Stuart-Hill 1992; Stuart-Hill & amount and type of habitat that will satisfy Aucamp 1993). The important role that the the MVP. In view of this, it is necessary for proposed mega reserve will play in conserv- realistic estimates of the spatial require- ing a diverse array of larger mammals, ments/densities of each the selected species including the top predators and a number of in the GAENP planning domain to be megaherbivores, is emphasised by Kerley & obtained. Boshoff (1997). The numerous ecological In summary, systematic data and information processes that are mediated by the larger are required to enable conservation planners mammals, or that they participate in, are to calculate the potential numbers of individ- reported on elsewhere (Boshoff et al. uals of each mammal species, within the 2001a). mammal habitats within various park config- The medium to large-sized mammals were uration scenarios. These data will enable selected as “target” species (sensu Wilcox planners to measure the effectiveness of the 1982) for the GAENP planning exercise proposed GAENP in achieving predeter- Koedoe 45/2 (2002) 86 ISSN 0075-6458 mined demographic, genetic and evolution- DISTRIBUTIONS ary targets for medium to large-sized mam- mals that can potentially occur in the park. In addition, they will inform decisions regard- Methods ing acquisition of additional land, where Two steps were followed in determining the poten- necessary, to achieve these targets, and help tial distribution of each species, within each MHC in identify species for which targets can only be the GAENP planning domain. met through metapopulation management. 1. Collation and interpretation of evidence that a species occurred, or could poten- APPROACH tially occur in all, or in a specific part, of the GAENP planning domain. The indigenous mammal species included in The early and recent published literature was con- this study (Table 1) are those with a mass sulted, as were conservation scientists and managers greater than ca. 2 kg (cf. Chew 1978), that with a good knowledge of the macro fauna of the are the most prominent on the landscape, and existing Addo Elephant National Park (AENP) and which are generally amenable to direct man- close environs (see Boshoff & Kerley 2001 and Boshoff et al. 2001b for details of the methods used). agement. As part of a separate exercise, 43 The mammal checklist for the AENP was also con- Land Classes were delineated through field sulted, as were the mammal collection registers of mapping by Kruger & Sykes (2002), using the Amatole Museum in King William’s Town, as a basis the hierarchical classification of where the terrestrial mammal collections from the Subtropical Thicket by Vlok & Euston- four provincial museums in the Eastern Cape are now housed. Brown (2002). It was considered impractical to use this detailed classification for deriving The present study attempts to reconstruct the distrib- utions