Browsing by Author "Bodasing, Marilyn Naomi."

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Feral cats (Felis catus) in an urban conservancy : University of KwaZulu- Natal, Howard College campus.
(2005) Tennent, Jaclyn Kim.; Downs, Colleen Thelma.; Watson, Helen Kerr.; Bodasing, Marilyn Naomi.
The resident feral cat (Felis catus) population on the University of KwaZulu-Natal (UKZN), Howard College campus (HCC) in Durban, South Africa was studied from March 2004 to November 2005. This study was initiated as the HCC is an registered as an urban conservancy and so should be removing alien invasive flora and fauna and conserving the indigenous biodiversity of the campus. This research was undertaken to assist with recommendations for the control and management of feral cats on the HCe. A survey to determine public perceptions and opinions regarding the feral cats was conducted among various communities on the campus. Feral cats from the resident population on the HCC were trapped and fitted with radio-collars in order that their home range sizes and distribution could be determined. Monthly census counts were also carried out in an attempt to calculate population densities of the feral cats on campus, while data on behaviour patterns was collected opportunistically throughout the study period. The survey showed that two extreme views existed on campus regarding the presence of feral cats. The university is a registered conservancy which some feel is no place for this exotic species. However, it is also situated within an urban surrounding and there are some cat enthusiasts among the public who feel that resources should be provided for the feral cats, both nutritionally and financially. While many people were unaware that the feral cats were a cause for concern on the HCC, the majority concluded that a management policy needed to be adopted to control feral cat numbers. Most were against the suggestion of eradicating the cats and strongly agreed with the implementation of a university funded feral cat IV sterilising and feeding programme. Feeding the feral cats, however, needs to be stringently controlled. In this study, the availability of an abundance of food resources was shown to be the primary influencing factor for home range size, cat distribution and population densities. It also had an overriding effect on the feral cats' behaviour patterns and activity levels. Once these had been initially established, other factors such as human activity, reproductive status and gender then came into play. Distribution of the feral cats around campus was not homogenous, and densities differed according to areas on campus. Highest cat densities were recorded in those areas on the HCC where permanent cat feeding stations had been established (usually the developed areas on campus), while no feral cats were sighted in the Msinsi Nature Reserve, a natural bush area on campus were no food resources (other than prey species) is available. Home range sizes of the feral cats were relatively small with a considerable amount of overlap between and within the sexes. There were also no seasonal differences in range sizes and diurnal ranges were only marginally smaller than nocturnal range sIzes. In terms of behaviour, the HCC feral cats were generally inactive, with passive behaviour such as lying down and sitting being most often observed. Although hunting activity was very rarely witnessed, the combined effects of feral cats supported at high densities by supplemental feeding may exert predation pressures that could be detrimental to both local prey and predator populations. Little social interactions were observed by the cats on the HCC. Other studies show that competition is greatly reduced if food is available in abundance and there is no need for territorial disputes if both food and a potential mate are located in close proximity. In the present study, this also means that immigrating feral cats from surrounding neighbourhoods are tolerated; another factor contributing to the increase in feral cat numbers on the campus. These findings suggest that the feral cat population on the HCC is being maintained at higher population densities than would be expected and management initiatives are needed to control the feral cat population at a minimum density through a sterilising and low key feeding programme so that it is acceptable to all concerned parties. However, the decisions need to favour the status of the HCC as a conservancy in an urban area as well as consider the well-being of the students and staffmembers in a public place.
Proximate factors influencing dispersal in the social spider, Stegodyphus mimosarum (Araneae, Eresidae)
(2002) Bodasing, Marilyn Naomi.; Slotow, Robert Hugh.; Crouch, Tanza.
Stegodyphus mimosarum Pavesi,1883 and S. dumicola Pocock, 1898 are two species of philopatric, inbred, permanently communal, non-territorial spiders that co-occur in parts of South Africa. The patchiness of colony distribution, limited dispersal capabilities and the observation of periodic, but rare mass dispersal events raised interest in factors influencing dispersal. The aim of this project was firstly, to determine which factors influence the spiders' readiness to leave a colony (two laboratory experiments), and secondly, to map nest dispersion in Weenen Nature Reserve, Kwa-Zulu Natal, and to use this to explain nest distribution. The first experiment assessed whether group size and variance in access to resources influenced the decision to disperse. Four colony sizes (8, 16,32 and 64) of S. mimosarum were established under a proportional feeding regime. I expected more spiders to leave larger colonies due to intra-group competition. However, there was no significant increase in the number of spiders leaving with increasing group size. Significantly more spiders left a colony during spring and when spiders were large. In the second experiment, I assessed whether the mean amount of food available, in liberally fed or starved colonies influenced the decision to disperse. Five colonies were fed daily on an abundance of prey items and five were starved. I expected more spiders to leave the starved colonies. However, a significant number of spiders left colonies where food was abundant. During a field survey nests were tagged within 40 plots of 50 m radius, and randomly. Retreat dimensions, height above ground, nest position, nearest neighbouring nests, and species were recorded. Nest status was tracked over six months to three years. I confirmed that nest height above ground was significantly higher for S. mimosarum. The two species differed in retreat volume and nearest neighbour distances. Most nests occurred on the northern aspect of trees. Few nests survived beyond three years, although many new nests were established. Access to resources influenced the decision to disperse. However, only well-fed (larger) spiders had the resources to relocate. Patchy nest distribution could be a consequence of nest site selection, short distance dispersal by budding and bridging, and long distance dispersal by ballooning.