Department of Forest and Wood Science

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Age assessment of the bushpig Potamochoerus porcus Linn. 1758 in the southern Cape
(Stellenbosch : Stellenbosch University, 1983-12) Seydack, Armin Hans Wilfried; Bigalke, R. C.; Stellenbosch University. Faculty of AgriSciences. Department of Forest and Wood Science.
ENGLISH ABSTRACT: The bushpig (Potamochoerus 2)orcus) is one of the least studied of the larger African mammals. This contrast to the other two African auids, the is in striking warthog (Phacochoerus aethiopicus) and giant forest hog (Hylochoerus meinertzhgeni), which have been subjected to detailed studies i.a. by Cumming (1970), D'Huart (1978) and Mason (1982). Because the bushpig is a prominent species both in the forest biome and on adjacent agricultural land, autecological research on the species is presently being undertaken to provide information needed for multipurpose forest management. This study on age determination is part of the broader research programme on the species.
Damage by baboons to pine plantations in South Africa : with special reference to the ecology of three troops of baboons in the Western Cape
(Stellenbosch : Stellenbosch University, 1993-01) Erasmus, Diane; Van Hensbergen, H. J.; Bigalke, R. C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest & Wood Science.
ENGLISH ABSTRACT: Baboon density in the study area was lower than in other studies, probably as a result of removal programmes. Troops had seasonal differenccs in home range utilization. Home range inc reased in summer as troops exploited local crops, and permanent water points. All troops showed a preference for plantations, as they provided shelter, food and protection. Data on feeding habits was collected by faecal analysis as baboons' fear had developed a fear of humans. Favoured foods were monocotyledonous and dicotyledonous plants, bulbs, seeds and cones. Xylem, phloem and cambium cells did not constitute a large proportion of the diet, nor was there any seasonal variation in occurrence. Dicots were selected in spring, pine cones in autumn (probably a selection for seeds not cones), insects in summer and bulbs in winter. The five favoured items were found throughout the year. Baboons have a few staple items which they supplement with seasonally available foods. Bark stripping is inhe.rent in baboons, despite the low energetic value of bark tissues. It is not known why all troops in plantations do not strip. Pine seeds and grasses play an important role in the diet, and may attract baboons into the plantations. Some mineral nutrients in the pine tree tissues varied seasonally. Levels in these tissues were comparable with levels in many plants consumed by baboons elsewhere. Zinc levels were higher in trees damaged by baboons than in other trees. Baboons may thus be selecting for zinc. This phenomenon, and the implications for managing baboon damage, needs further research. 37% of plantations in South Africa experienced baboon damage. This was not restricted to any particular area or species of pine. Less than 15% of the compartments on any station showed damage. On average, less than 25% of the trees within a particular compartment were damaged. Increase in damage within a plantation was isolated. No relationship was found between damage and environmental factors. Less than 2% of the total compartments in South Africa and less than 1% of the total area afforested show damage. Baboon damage at Kluitjieskraal State Forest affected 6% of all compartments. Less than 25% of the trees in these compartments were affected. Damage to the trees varied in severity. Patterns of damage were determined and were found to differ between areas within a plantation. A precise estimate of financial losses on a national scale is not possible due to many complicated factors and the considerable lack of available data. An assessment of-the severity of the damage is provided. Authorities must determine whether it is practical and economical to introduce control measures. Indications are that the losses in South Africa amount to less than R5 000 000 on present areas afforested. Information on control programmes in the Western Cape is scarce, although control has been carried out in Forestry areas for many years. The effectiveness of electric fencing to decrease damage levels is discussed. It is imperative to understand the population dynamics of specific baboon populations to exercise effective control.
Ecology of the bushpig Potamochoerus porcus Linn. 1758 in the Cape Province, South Africa
(Stellenbosch : Stellenbosch University, 1990-12) Seydack, Armin H. W.; Bigalke, R. C.; Stellenbosch University. Faculty of Agrisciences. Dept. of Forest and Wood Science; Jacobs, Ivan
ENGLISH ABSTRACT:Bushpig sociology, energetics, reproduction and population dynamics were studied over an 8-year period in the Cape Province, South Africa. The social organization was found to be strikingly different from that known from other suid species. The basic social unit is a unimaternal family group, occupying a resource-based territority, with a monogamous mating system. This form of social organisation is related to the dispersed nature of food resources, to which it provides exclusive access. It is reminiscent of canid social systems. Agonistic behaviour, communication and maternal behaviour were studied as the opportunity arose. The average home range size was 7,2 kmª, ranging from 3,8 to 10.1 kmª. Home ranges were often traversed within 1-4 days, as part of territory patrolling. The average diel ranging distance was 3 km. Bushpig were active during both night and day and exhibited a basic bimodal rhythm. The main phase of intensive foraging occurred from before dusk to midnight, with a secondary activity peak after dawn. Activity schedules were geared to avoid extreme ambient temperatures. Temperature regulation and water use were investigated, with particular reference to thermoregulatory behaviour (nest building). pelage characteristics, body core temperature dynamics, thermoneutral zones and resting metabolic rates. The thermoneutral zone for 10 kg bushpig juveniles was estimated to lie between 13° and 30°C and that for adults between 8° and 25°C. Foraging behaviour, diet and its nutritient content were investigated. Regional differences in the nutritional quality of bushpig diets in the Eastern and Southern Cape were associated with the predominance of nutrient-rich and nutrient-poor substrates respectively. These in turn were reflected by divergent life history features in the populations from the two regions. Patterns of growth and energy storage were described and the value of various parameters (e.g. mass to size ratio, fat depositions, blood composition) to evaluate condition was investigated. In studying reproductive biology, sexual maturation, female reproductive cycles, prenatal litter statistics, foetal development, 1actation, breeding seasonality and reproductive turnover were the main aspects addressed. The role of food quality, body condition and social status in determining reproductive success was discussed. Bushpig population density estimates in the Southern Cape ranged between 0,3 and 0,5 animals/kmª• The dynamics of Southern and Eastern Cape populations were found to differ. The differences are consistent with the hypothesis that social organisation is determined by the distribution and availability of food while diet quality shapes life history tactics. A life history model was developed which links edaphoclimatic environmental conditions with diet quality, metabolic turnover rate and, ultimately, life history features. In the concluding chapter some of the managerial implications of the research findings are discussed.
Habitat partitioning, and an assessment of habitat suitability using presence data, of a large herbivore communitiy on a Zimbabwean private wildlife reserve
(Stellenbosch : University of Stellenbosch, 2003-12) Traill, Lochran (Lochran William); Bigalke, R. C.; University of Stellenbosch. Faculty of Agrisciences. Dept. of Forest and Wood Science.
ENGLISH ABSTRACT: The factors determining habitat selection of large herbivores, on a private wildlife reserve in semi-arid southeastern Zimbabwe, were investigated. Gross vegetative structure, herbaceous composition and topographic features thought to determine herbivore distribution were measured. Seasonal variation in resource distribution was considered, and research therefore extended over an entire year. Herbivore distribution and ecological niche separation was explained through several important environmental variables, and potential for inter-specific competition inferred. Additionally, predictive habitat suitability models were designed for each of the grazing species in the critical dry season. Herbivores showed a large degree of niche overlap in both the hotwet season and the cool-dry season, when food resources were more plentiful. Niche separation between grazers was pronounced in the hot-dry season. Herbivore distribution was associated most closely with distance to water, grass sward height, time since burn, woody plant density and by the presence of predominant grasses, these being Urochloa mossambicensis, Panicum maximum, Heteropogon contortus and Digitaria eriantha. Ecological separation of herbivores by the grasses P. maximum, H. contortus and D. eriantha was more indicative of associated environmental variables than feeding niche separation. A GIS-based analysis, using species presence data and quantitative coverages of environmental variables, produced maps of gradations of habitat suitability for grazing species during the dry season. Results of both analyses were integrated and gave a better understanding of ecological separation, and possible competitive interactions, among the large herbivore community on Malilangwe Estate. Recommendations were made based on the interpretation of findings, within the context of available management options.
Prospects for sustained harvesting of mopane (Colophospermum mopane) on the Venetia Limpopo Nature Reserve and its implications for browsing ungulates
(Stellenbosch : Stellenbosch University, 1996-03) Cunningham, Peter Low; Bigalke, R. C.; Van Hensbergen, H. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.
ENGLISH ABSTRACT:Principle objectives of this study were to investigate the ecological feasibility of sustained utilization of mopane, using Venetia Limpopo Nature Reserve as a pilot study area. The study was limited to three different mopane dominated vegetation types on the reserve with most research being conducted in C.mopane woodland. Results can be summarized as follows: 1. Colophospermum mopane is ubiquitous on VLNR. 2. C.mopane woodland has the deusest mopane growth of the three vegetation types and highest densities are found on soils (OaB, VaB, Du, SwB & VaA) in association with C.mopane woodland. There seems to be a correlation between mopane density and soil type. 3. Largest mopane trees according to height and circumference were found in C.mopane/C.apiculatum open woodland. There is no significant difference between height and circumference on different soil types. 4. Most senility occurs in C.mopane shrubland and there is a significant difference in senility between mopane associated with different soils on which this vegetation type occurs. 5. Oldest average ages per tree were fo•.md in C.mopane woodland while growth rates were fastest in C.moparse!C.apiculatum open woodland. 6. There is a significant positive correlation between total and charcoal weights for mopane. Total and charcoul weights per tree were highest for C.mopane/C.apiculatum open woodland, while weights per hectare were highest for C.mopane woodland. Soils could not positively be associated with this trend. 7. Mopar.e lends itself to harvesting, especially C.mopane ••10odland in the Endora, Lizzulea and Hilda areas. Winter months seem to be most desirable for harvesting activities. Hand felling in elongated patches (increases ecotone boundary) is recommended where labour is cheap. A harvesting strategy of between 25% and 50% would make the operation economically viable and ecologically acceptable. An optimum harvesting rate of 27% is suggested by a harvesting model developed specifically for this mopane data. 8. Total herbivore densities, distribution and species proportions can be expected to change following bush clearing. Habitat for grazers should increase due to an increased grass production. Habitat for browsers should not be influenced much. Effect of noise and human disturbance during harvesting, especially for elephants is negligible, as hunting activities already take place on VLNR. 9. Grass production would increase but quality should decrease after harvesting, due to an increase in low quality opportunistic species, especially if soil disturbance takes place. Grass quality is best in association with herbaceous species such as Salvadora angustifolia. Carrying capacity for grazers should increase after harvesting as a result of habitat change and grass biomass increase. 10. Total browse production would decrease but leaf biomass should increase on remaining trees as they have improved water availability due to Q lack of intra specific competition. Higher seed production and more flowering takes place at lower tree densities. Greatest advantages for browsers after harvesting, is the fact that leaves become senescent later in autumn and that spring leaf flush takes place earlier thus prolonging bro\'se availability.
The roan antelope (Hippotragus equinus, Desmarest 1804), its ecology in the Waterberg Plateau Park
(Stellenbosch : Stellenbosch University, 1993-01) Erb, Karl Peter; Bigalke, R. C.; Van Hensbergen, H. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest & Wood Science.
ENGLISH ABSTRACT: This study was undertaken in the Waterberg Plateau Park in northern Namibia. Field work took place between January 1988 and September 1989; however relevant information collected since, has been included. The roan antelope population in the reserve stems from re introduced animals. A total of 93 were brought in between 1975 and 1981. By 1984 the population peaked at 275 individuals. 186 roan have since been captured and, sold. The main objective of the study was to develop a better understanding of the management requirements for this population of rare antelope. Approximately one-fifth (32 individuals) of the population was marked with eartags or plastic collars or both. Five animals were radio-collared. This is the first detailed study of. roan ante lope in such a large study area (40 000 ha), with such a large population and so many marked individuals. Chapter 3 deals with population dynamics. It is believed that the entire population was accurately counted, aged and sexed. The adult sex ratio was skewed in favour of females, despite the absence of predators large enough to kill adults. The majority of calves were born during the wet season, from the end of August to March. A positive relationship between early season rainfall and the calf crop in the subsequent year was found. The ratio of juveniles per 100 adult females averaged 4.1 over seven years. Recorded mortality was too small to identify significant factors. Two deterministic population models were developed for exploratory simulations and are presented in Chapter 4. Both simulations were fairly successful, giving good correlations with the actual counts. Nutrition is covered in Chapter 5. Simple nutrient budgets revealed that protein and phosphate requirements were probably not met in the dry season. Calculations based on hand selected forage samples and nutrient requirements of cattle, show that adult roan obtained 15-28% of their crude protein requirements and approximately 10% of the phosphate in the dry season. The social system of the roan is described in Chapter 6. Four different clans were recognized, each with a distinct home range. The breeding groups in each clan were unstable, splitting up and rejoining at random. Adult males exhibited territoriality during the breeding season, which is in contrast to most other studies where harem groups were observed. Outside the breeding season, dominant males rejoined bachelor groups or remained solitary. Home range size and configuration were described using different methods. Home ranges averaged 4800 ha for two clans _'0.-_. and the territory size of one male was estimated to be 1200 ha within a much bigger home range. Distinct wet - and_dry - season ranges could be distinguished. Habitat selection is discussed, and was determined primarily by feeding requirements. Forage quality was identified as the major limiting factor and thus the primary determinant of habitat use. In Chapter 7 management recommendations and research proposals are made to ensure sustainable utilisation, by both live capture and game viewing.
The Southern African Bird Atlas Project and its relevance to nature conservation
(Stellenbosch : Stellenbosch University, 1993-09) Harrison, James Adriaan; Van Hensbergen, H. J.; Bigalke, R. C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest & Wood Science.
ENGLISH SUMMARY: The objectives of this thesis are to: (a) describe the Southern African Bird Atlas Project (SABAP), document its progress and assess its success, as a contribution to the planning of future projects; (b) explore the potential of atlas data to answer questions other than those concerned with the ranges of species; (c) investigate the application of bird atlas data to some specific questions which have a bearing on the planning and practice of conservation. The progress and organizational features of SABAP and its databank are described. It is shown that the SABAP has been a success in terms of the large volumes of accurate and up-to-date data on species' distributions and patterns of seasonality acquired. The decision to use amateur volunteers is shown to have been appropriate but not without drawbacks. A methodological point made is that the methods of atlasing and of computerization of the data need to be planned so as to permit statistical analysis of the data. If this is done, reporting rates can provide an index of relative abundance which can, in tum, permit the application of atlas data to many questions beyond that of range extent. The analysis of reporting rates is illuminating in the description of seasonal patterns of occurrence and therefore, of seasonal movement. This is demonstrated for long-distance migration and for local movement. The papers dealing with patterns of seasonality highlight the fact that species with extensive seasonal movements cannot be conserved within, single reserves. The growing demand for access to SABAP data is reported and the applications listed. Improvement of SABAP's relevance to the environmental consultancy user group is achieved by a method of presenting atlas data in a manner which will maximize their usefulness. The approach hinges on the ability to allocate species to habitat categories. This enables one to break down an undifferentiated species list for a grid square into a number of habitat-specific species lists. It is proposed that atlasing could be adapted to achieve population monitoring objectives. One exercise set out to analyse changes in reporting rate through time and to correlate these with a key environmental variable, namely rainfall. The exercise is only a limited success. It is shown that, while potential to use atlas methods for population monitoring does exist, the need to improve the standardization of methods for this purpose is crucial. Interim results of the SABAP in the form of species distribution maps are presented as an aid to the planning of conservation action for cranes. The information for the three species is compiled to produce a map which highlights those grid squares which have the greatest diversity of cranes. It is shown that the combination of atlas information for a suite of species can yield an index of diversity which may hold greater potential for planning the location of reserves than the distribution maps of individual species alone. Trends in bird atlasing and of the use of reporting rate as an index of relative abundance are reviewed as is the use of reporting rates as a population monitoring tool.

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