HOME RANGE, BEHAVIOUR, AND RECRUITMENT RATES OF TWO BLACK RHINOCEROS POPULATIONS

The results of the studies indicate that the rhinoeeros population of the Ngorongoro Conservation Area is considerably higher than was formerly believed.

Abstract

Summary During the period 1964 – 1966 biological studies were conducted of two black rhinoeeros Diceros bicornis L. populations in northern Tanzania. One population occupies the caldera of Ngorongoro and the other the area in the vicinity of Olduvai Gorge. Detailed records were made of each rhinoeeros observatson and 182 individuais were seen in the two study areas during the three‐year period. The black rhinoeeros is a very sedentary species, and the size of the home range is governed by several factors which are described in the^text. The home range of an immature rhinoeeros is larger than that of an adult individual. The adult rhinoeeros, especially the male, is essentially a solitary animal, but immatures frequently join up with a companion. Activity patterns are described and illustrated, and are similar in the two study areas. Behaviour of the species follows welldefined patterns, and territorial behaviour is uncommon. Vocal communication in the species is described. The significance of dung piles, used regularly by the species, is considered and the results of experiments iflsing faecal samples are described. Relations with two carnivores are discussed. The recruztment rates of the two populations are almost identical, i.e. 7.0% at Ngorongoro and 7.2% at Olduvai. Various reproductive characteris‐tics affecting recruitment rates, such as age at maturity, gestation period and interval between successive calves are described using records obtained from zoological gardens and from field observations. The results of the studies indIcate that the rhinoeeros population of the Ngorongoro Conservation Area is considerably higher than was formerly believed. The future of the species in the area appears favourable, providing its habitats are not destroyed through encroaching cultivation.