Volume 31, Issue 3 & 4, October 2001

The avifauna of riparian-Pinus habitat edges at Mooiplaas forestry estate, KwaZulu-Natal, South Africa
Malan, G. 73-84

Abstract: This study investigated species diversity and habitat use by birds of riparian-plantation edges. These edges represent the boundary between extensive, exotic pine plantations and narrow, indigenous riparian strips. The avifauna was sampled in the middle of four riparian thickets (dense shrubs and low forest trees), on the riparian-plantation edges and inside seven-year-old commercial pines on a forestry estate in KwaZulu-Natal province, South Africa. Of the 49 bird species recorded, 65% were recognized edge species. Very abundant birds were also predominantly edge species that occurred in two or all three of the habitats. Hole-nesting species avoided the edge and plantation, whereas birds that crossed from the riparian thicket into the plantation were mostly species with wide habitat tolerances and diet preferences. Species richness, abundance (per 25-m radius point count) and diversity decreased from the riparian thicket, through the edge to the plantation habitat. Given that an estimated 42 549 km of riparian-plantation edge has been established on 531 860 ha of commercial plantations in KwaZulu-Natal, even if the above trends signal a small diversity loss on a local scale, the overall negative effect on riparian bird diversity may be substantial and requires further investigation.

Relationship between distribution of kudu and woody plant structure
Dorgeloh, W.G. 85-91

Abstract: The seasonal distribution of kudu (Tragelaphus strepsiceros) in relation to the woody plant structure and forage availability has not yet been investigated in the Nylsvley Nature Reserve. The objective was to identify significant habitat variables influencing the distribution of kudu and to construct a model for predicting kudu distribution. Manly's a index showed that kudu selected the Aristida bipartita-Setaria sphacelata Savanna variation throughout the year, probably because of the abundance of young Acacia karroo in this plant community. Bachelor males also preferred plant communities on lithosol soils, with Combretum species as the common tree. The analysis of variance and Tukey's test showed that plant communities generally differed significantly (P < 0.05) from one another in terms of woody plant structure and forage availability. Multiple regression analysis was used to construct predictive models for kudu breeding distribution. Eight significant habitat variables were isolated for the summer model y = b₁ woody plant density + b₂ %woody canopy cover + b₃ leaf volume + b₄ leaf mass + b₅ leaf mass below 2 m + b₆ browse tree equivalent + b₇ foliage height diversity of maximum canopy diameter + b₈ foliage height diversity at lowest leaf. The winter model consists of four variables y = b₁ woody plant density + b₂% woody plant canopy cover + b₃ foliage height diversity of maximum canopy diameter + b₄ foliage height diversity of lowest leaf. Model variables suggest that habitat utilization by breeding herds was influenced by forage availability, measured as leaf volume and leaf mass, within a feeding height of <2 m and with a high structural diversity. Woody plant density and percentage canopy cover probably also serve as cover for protection. The winter model would be most applicable to predict breeding herd distribution. However this needs to be tested against independent data before it can be applied successfully.

Gross bacterial contamination associated with mortality in catfish fingerlings during transportation
Nzeako, B.C.Okafor, N.Inyang, M.M. 93-97

Abstract: The causes of mortality in catfish (Clarias gariepinus) fingerlings during transportation to stocking ponds are described. Twenty of 150 fingerlings collected from perennial ponds died on their way to the stocking ponds, and on bacteriological examination of their kidneys, livers and spleens, Aeromonas hydrophila (64.3%), Klebsiella pneumoniae (7.1%), Burkholderia cepacia (14.2%), Plesiomonas shigelloides (7.1%) and Acinetobacter anitratus (7.1%) were isolated. On re-inoculation of isolates of A. hydrophila into new fingerlings, 60% of the inoculated fish died. When oxytetracycline (31 mg/l) was added to water in which the fingerlings were transported, the mortality rate was reduced from 13.3% to 4.0%. It is recommended that the stocking of ponds with fingerlings scooped from the banks of rivers should be discontinued and that ponds should rather be stocked with fingerlings from hatcheries for which the brooding stock and bacterial profiles are known. Although the addition of oxytetracycline to water used for transporting fingerlings reduced the mortality rate, environmental considerations such as the possible emergence of antibiotic-resistant strains of bacteria render this practice unacceptable.

The influence of tree thinning on the vegetative growth and browse production of Colophospermum mopane
Smit, G.N. 99-114

Abstract: The vegetative growth and browse production dynamics of Colophospermum mopane trees were studied over a period of three years on six plots where the trees were thinned to the approximate equivalents of 75, 50, 35, 20, and 10% of tree density of the control plot (2711 trees/ha). Thinning reduced inter-tree competition which resulted in significant increases in the vegetative growth of the remaining trees. As the intensity of thinning increases, the magnitude of these increases also increases. On a structural basis, vegetative growth within the trees was not uniform and the trees showed increases in canopy cover rather than increases in tree height. Although the vegetative growth per tree was higher in the low tree density plots, the larger number of trees in the high tree density plots ensured that the total seasonal leaf dry mass increase exceeded that of the low tree density plots. September to December are the critical months as far as vegetative growth is concerned. Tree thinning reduced the available browse at peak biomass, but trees from the low tree density plots displayed a better distribution of browse, having leaves in comparatively younger phenological states over an extended period. Marked differences in the nutritional composition and water content of C. mopane leaves existed in different phenological states.

Habitat selection and small mammal prey availability of the gaboon adder in Zululand (KwaZulu-Natal), South Africa
Perrin, M.R.Bodbijl, T. 115-126

Abstract: In Zululand, the gaboon adder (Bitis gabonica gabonica) requires a forest-thicket-grassland mosaic that enables foraging along forest margins and adjacent grasslands. Since it faces a decline in prime habitat owing to a numerically and spatially increasing human population, habitat conservation is essential. This can be achieved by maintaining forest-thicket-grassland mosaics, and by linking these, through migration corridors, to existing natural habitat. Small mammals (Otomys spp. and Aethomys chrysophilus) are the major prey of gaboon adders and are common in its preferred habitat. Seasonal variation in relative small mammal abundance was correlated temporally with the autumnal breeding season following rains.

Diet and prey selection of the gaboon adder in Zululand (KwaZulu-Natal), South Africa
Perrin, M.R.Bodbijl, T. 127-134

Abstract: Following gut content analyses and observation of prey selection, the diet of gaboon adders (Bitis gabonica gabonica) was determined in relation to prey abundance in Zululand (northern KwaZulu-Natal Province), South Africa. Examination of live, wild-caught snakes and preserved museum specimens revealed a diet comprising predominantly small mammals (82.3%) and ground-dwelling birds (17.7%). Adult snakes fed mainly on common, large rodents (vlei rats, Otomys spp., and red veld rat, Aethomys chrysophilus), weighing 5-20% of the snake's body mass, whereas juvenile snakes preyed on shrews (Suncus sp.) and juvenile A. chrysophilus. Gaboon adders required an old-growth forest/grassland mosaic where prey were abundant.

Immobilization of free-ranging adult male southern elephant seals with Immobilon™ (etorphine/acepromacine) and ketamine
Ramdohr, S.Bornemann, H.Plotz, J.Bester, M.N. 135-140

Abstract: Twenty-seven free-ranging adult male southern elephant seals (Mirounga leonina) were immobilized to enable attachment of satellite-linked dive recorders (SLDRs) and to obtain biopsy specimens. Large Animal Immobilon^™ (LA Immobilon^™) was injected remotely to achieve initial sedation (x = 0.0009 mg/kg etorphine; 0.0037 mg/kg acepromacine) while ketamine was injected manually on demand to maintain narcosis (x = 81 min). The total dosages (x = 1.7 mg/kg) of ketamine required were negatively correlated with those of LA Immobilon^™ (P < 0.01). The dosages of LA Immobilon™ were approximately 15-30 times lower than recommended for other large-sized mammal species, and the therapeutic range was low. Nine cases required the application of the etorphine antidote Large Animal Revivon^™ (x = 0.0052 mg/kg diprenorphine) injected intravenously (n = 3), intramuscularly (n = 5) or sublingually (n = 1). LA Immobilon^™ appears to be useful to attain immobilization in free-ranging, adult male southern elephant seals by remote injection owing to its high potency and hence small volume required. It must, however, be used sparingly and ideally only for initial sedation owing to its potential danger and narrow therapeutic margin.

Economic returns and allocation of resources in the wildlife sector of Botswana
Barnes, J.I. 141-153

Abstract: Wildlife utilization in Botswana was studied to find out (1) whether it generates positive contributions to national income, and (2) which combinations of uses can generate most income. Financial and economic models of different land uses were combined in linear programming and cost-benefit analyses. Results show that the wildlife resource in Botswana can contribute positively to national income, and this justifies government investment in the sector. The sector is economically efficient, and contributes to Botswana's economic development. Wildlife uses need to be fully developed in ways that maximize their economic contributions. Non-consumptive tourism on high-quality wildlife land will give the greatest economic returns, and should get priority. Safari hunting, community-based wildlife use (where viable), and limited intensive ostrich and crocodile production should also be given priority for investment. Other uses should get lower priority, but all should be developed. On about a third of wildlife land, wildlife uses have a clear economic advantage over livestock uses. The remaining two thirds of wildlife land has poor capacity to generate use value. Here, commercial livestock ranching is not an economic threat, but traditional livestock keeping is. A ban on consumptive wildlife uses in Botswana would significantly exacerbate this threat.

Tourism, protected areas and development in South Africa : views of visitors to Mkambati Nature Reserve
Kepe, T. 155-159

Abstract: Tourism to areas of natural beauty has recently been seen as one of the fastest growing interests in many countries around the world. This brand of tourism also encompasses celebrating and sharing with tourists the uniqueness and diversity of different cultures in areas visited. Through a case study of current tourism trends in Mkambati Nature Reserve on the Wild Coast, where an ambitious ecotourism project under the auspices of the Spatial Development Initiative (SDI) is planned, this paper attempts to emphasize the role played by local visitors in making ecotourism a success or failure. The study found that local tourists are currently the majority of visitors to Mkambati Nature Reserve. It also shows that while unimpressed with infrastructure and other services, local tourists are prepared to spend money to enjoy the quietness that is offered by protected environments. However, local tourists to Mkambati are not as enthusiastic about visiting and sharing experiences in adjacent rural areas. If based on current trends, then planning of ecotourism ventures should, at least initially, be based on local visitors' patterns.

Declining populations of helmeted guineafowl in the Midlands of KwaZulu-Natal, South Africa : a review of causes and remedies
Ratcliffe, C.S.Crowe, T.M. 161-171

Abstract: Populations of helmeted guineafowl (Numida meleagris) have declined significantly within the Midlands of KwaZulu-Natal Province, South Africa, since the early 1980s. A three-phase project was initiated in 1995 to assess the possible cause(s) of this decline. Initial research investigated socioeconomic factors such as illegal hunting, whereas subsequent statistical analyses, based on questionnaires, revealed correlations between guineafowl population densities and certain land-use practices. Further research focused on other possible causal factors including hyper-fragmentation of the habitat matrix, misuse of agrochemicals, disease, genetic contamination and dietary constraints. Results indicate that, although all these factors might have proximal, negative effects on local populations, there is no evidence to suggest widespread action of any single factor. Radio-tracking of guineafowl at several sites revealed that healthy guineafowl populations thrive in moderately fragmented landscapes, and that hyper-fragmentation of these habitats through increased, intensive crop agriculture, coupled with modern, `clean' farming techniques, is largely responsible for observed declines in guineafowl populations due to population fragmentation and an undermining of meta-population structure. Resuscitating guineafowl populations to sustainable levels involves creating suitable habitats on a landscape level through management strategies at the conservancy level, with the objective being to strive for habitat diversity and connectivity.

The nature, antecedents and role of South African kudu hunters' expectations in sustaining a competitive advantage
Radder, L. 173-178

Abstract: Hunting is an experience that, to a great extent, consists of ideas, expectations and a hope for fulfillment. Knowing what the hunter expects is the first and possibly the most critical step in delivering a quality experience. Being wrong about what the hunter wants could mean: losing his business if another game rancher better meets his expectations, or expending money, time, and other resources on products and services that do not matter to him. This could result in failing in a progressively competitive market. Because customer expectations are pre-trial beliefs or desires about service delivery that serve as points of reference against which performance and quality is judged, it is important that game ranchers understand the nature and antecedents of hunters' expectations. Effectively managing adequate, desired and predicted expectations about the hunting experience, along with perceived performance, can intensify hunters' loyalty to a point where they are unreceptive to competitive offers. To develop immutable loyalty, ranchers should stay alert to the need for service improvements and consistently exceed both adequate and desired service levels.

Assisted re-establishment of a resident pride of lions from a largely itinerant population
Hoare, R.E.Williamson, J. 179-182

Abstract: Lions (Panthera leo) resident around the shores of Lake Kariba in Zimbabwe are vulnerable if their home ranges include communal lands inhabited by subsistence farmers. The primary cause of death is strangulation in wire snares set by game-meat poachers but illegal poisoning of carcasses, legal safari hunting and natural predation also contribute to mortality. A protected enclave of land on the lakeshore supported a resident pride of lions which was gradually eliminated in 1995. Tourist demand warranted an attempt to reintroduce lions which was assisted and probably accelerated by the capture and temporary confinement of an adult female lion and her three cubs in a stoutly constructed boma. The female came into oestrus and attracted several itinerant young male lions back to the area. The subsequently released lion family and five immigrant males formed the basis of a new resident pride which reproduced and behaved normally, attracting other lions who challenged the social hierarchy.