ELEPHANTS AND HABITATS IN NORTH BUNYORO, UGANDA

Summary The paper is concerned with the changing relation between elephant populations and vegetation in north Bunyoro, Uganda. The history of the area over the past 100 years is briefly described, particularly in terms of changing human populations and contraction of the elephant range. The main features of the environment, including vegetation types and distribution, annual burning, other species of large mammals (including the results of aerial counts) and birds are described. The main results of investigations on the elephant populations in the area, dealing with numbers, distribution and movements, population density distributions, and social organisation iocluding group size frequencies and structure, are presented. From a population of about 10,000 elephants over 1,000 have been cropped or shot on control in the area since 1965. The results of detailed analyses of material derived from these operations are presented and discussed. Material from the cropping operations represents a cross‐section of the population and all animals sampled have been aged from the dentition. It is concluded that the mean daily food intake (wet weight) is 4% of live weight for all classes except lactating females; results of studies of food quality are discussed and a possible explanation for the de‐barking of trees presented. The physical condition of elephants in several populations has been compared and appears to be poorer when less browse is available. Growth equations are presented for height and weight; the male shows a post‐pubertal growth spurt. Various reproductive parameters are examined including age at puberty, pregnancy rate, and the seasonal cycle. Seasonal conceptions are delayed in North Bunyoro in relation to their timing north of the River Nile and it is suggested that the delay is nutritionally‐induced. Recruitment has been falling in this population and this decline is likely to continue in the absence of effective management. Some undesirable consequences of extensive control‐shooting are mentioned. The analysis of the elephant populations indicates that they are at densities in excess of the carrying capacities of the habitats, and the continuing changes in these habitats are described. In the grassland and wooded grassland areas the destruction of woodland has progressed radially, a zone of damage about 15–20 km wide having moved outwards through the range. This is consistent with destruction mainly by elephants rather than by fire. The influence of elephants on the forest edge and on the areas of regeneration inside the forest, created by management, is described. Finally specific proposals that have been presented to the National Parks and Forest Department are discussed. These involve rational cropping of over 4,000 elephants over the range and the construction of elephant‐proof barriers, the control of fire, and the declaration of a Conservation Area with a statutory Authority on which the various interests concerned would be represented.