Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 63-68). Description: viii, 68 leaves : map ; 29 cm. / The ability of the Pigeon Guillemot Cepphus columba to rear an additional chick was tested by manipulating clutch sizes. The effect of the manipulations on growth, and hatching, fledging, and egg success was measured in chicks from experimental, natural, and control nests. No significant differences were observed between the nest types. Data from 1983, 1984, 1985, and 1989 were analyzed for potential differences in reproductive success of one and two egg clutches. The ratio of one to two eggs was significantly higher in 1985 and 1989. Hatching and fledging success was significantly higher for two egg clutches in 1985 and 1989. No significant differences were observed for egg success. Egg volume was significantly greater in two egg clutches in 1983 and 1984. Egg volume was correlated with fledging but not with hatching success.

Often perceived as pests, pigeon control is applied without investigating environmental, ecological and anthropogenic factors which affect their populations and response to controls. Estate Management of the University of South Africa’s Muckleneuk campus identified a need to investigate and address a perceived pigeon problem. Staff perceptions regarding the presence and attitude towards control of the pigeons was undertaken through an online Survey Monkey questionnaire and semi- structured interviews until saturation was achieved. It was determined that the a s sumed negative perception towards the pigeons was in fact incorrect. Participants would rather encourage the nesting and breeding activities of pigeons on campus, as they felt that the human–pigeon interactions and viewing of squabs in nests contributed positively to their work environment. Participants did not consider the pigeons or their related activities to pose a problem. It was felt that should control be imposed, the birds should rather be humanely managed through non-lethal measures rather than eradication. Pigeon numbers on five buildings on the University’s campus were counted at dawn and dusk, every week, for two years. The first year provided baseline data and the second year was when control measures were applied. The study determined that the pigeon population index fluctuated seasonally while breeding occurred throughout the year, with notable peaks and declines relating to physiological and population dynamics. The pigeons seemed to make opportunistic use of crop availability in surrounding farmlands during optimal production periods, while conserving energy when not favourable. Site selection in relation to building aspect indicated significant differences in all the seasons except for winter, while a positive significant relationship between level height and pigeon number was recorded. Once the control measures were applied, the total pigeon index on the campus declined by 50%. Control structures differed significantly in efficacy. Bird spikes indicated the highest efficacy at reducing the pigeon population index and seasonality did influence this efficiency. Birds of prey and an audio bird scarer were used to compare actual versus implied predator presence, it was determined that there was an association between method of scaring and the number of pigeons observed on the different time periods. Pigeons were observed to continue the natural trend of dispersion and return at the dawn and dusk counts during the audio bird scarer trial without being actively discouraged or dislodged from the building. Pigeons reacted positively to the visual raptor presence, which caused them to take flight from the buildings. The visual effect was only temporary however as pigeons returned once the threat had been removed 10 minutes post scare. The studies concluded in an interdisciplinary management plan presented to the University Estates. / Environmental Science / M. Sc. (Environmental Science)