Population Ecology of the Uganda Kob (Adenota kob thomasi (Neumann)) in Relation to the Territorial System in the Rwenzori National Park, Uganda

Abstract

The Uganda kob, Adenota kob thomasi (Neumann) used to be widespread throughout Uganda in all suitable regions but now the main concentrations are found in the Rwenzori and Kabalega Falls National Parks as well as in the Toro Game Reserve on the southern shores of Lake Mobutu (formerly Lake Albert). Smaller numbers occur around Lake Kyoga and in southern Karamoja. The peculiar territorial system of the kob was discovered and described by Buechner (1961) from the Toro Game Reserve which lies 70 km north of the Rwenzori National Park. The kob resembles other ungulates in its social structure with three groupings of nursery herds, bachelor groups and territorial males, respectively. In most antelope species, the territorial male defends an area of ground sufficiently large to supply food and cover and such males are found in the kob but, in addition, there are others that defend very small territories which are clustered together into an area very similar to the lekking grounds of certain game birds. These territorial grounds, which are recognizable from the trampled vegetation, vary in size from 200 to 400 m across and contain from ten to twenty territories in the central core with as many again of slightly larger and more widely spaced territories on the periphery. Leuthold (1966) observed the two known territorial grounds in the Rwenzori National Park, but a detailed study of the kob has been made only in the Toro Game Reserve and the present work was undertaken to see if this type of behaviour was typical of other populations and to examine the theory (Buechner 1961; Leuthold, 1966) that there is a correlation between high kob densities and the territorial ground system. This involved a study of the population structure and dynamics of the kob and the results of these aspects are reported here. The Rwenzori National Park has been described by Spinage (1970) and details of the vegetation are given by Osmaston (1971) and Lock (in press). It contains forests, swamps, lakes, rivers, woodland and grassland. Kob are restricted to the grassland much of which is burnt during the dry seasons (Eltringham, in press a). Field (1968) classifies the grassland into three categories. (a) Tall fire climax communities. The dominant grasses are Cymbopogon afronardus Stapf and Imperata cylindrica (L) Beauv. (b) Medium, fire climax communities. Found in low rainfall areas with Hyparrhenia filipendula (Hochst.) Stapf and Themeda triandra Forsk. as the main species. Thickets of Capparis tomentosa Lam. often enclosing candelabra trees (Euphorbia candelabrum Trem. ex Kotschy), are usually dispersed throughout the grasslands. Other trees such * Present addresses: 737 Sheppard Street, Winnipeg, RZP OE6, Canada and Department of Applied Biology, University of Cambridge, Pembroke Street, Cambridge CB2 3DX.