The social system of the white rhinoceros

Abstract: Results of behavioural study carried out on the white rhinoceros in Zululand, South Africa, between 1966 and 1971 are summarized. Cohesive social groups included cow-calf pairs, adolescent groups, cow-adolescent groups, cow-cow groups and adult male singletons; the largest group numbered six. Adult males occupy territories of about 2 km2 for periods of several years. Olfactory marking is carried out by dung-scattering and urine spraying. There are subordinate adult bulls which coinhabit certain territories, but do not perform territory marking. Cows have overlapping basic home ranges covering about 10-12 km2 but at times they may wander further afield. Some adolescents are resident, others semi-nomadic. There are ritualised encounters between neighbouring territorial bulls, while subordinate bulls adopt a defensive threat posture when approached. A deposed territorial bull is not driven out of his territory but becomes a subordinate bull. Territoriality is characterised as a spatially localised dominance. Reproduction is year-round with seasonal peaks. A consort period of 5-20 days precedes mating. A bull manoeuvres to confine the oestrous cow to his territory. Courtship approaches last 15-20 hours and copulation 20-30 mins. Subordinate bulls do not mate with cows. Gestation is 16 months. The new-born calf remains shaky for 2-3 days. When alarmed it runs off ahead of the cow. Weaning commences at 2 months, but nursing continues to well over a year. The older calf is driven away upon the birth of a new calf. It then bonds onto another adolescent or a cow without a calf. Females have their first calf at 6-7 years, but a male is probably over 12 years before he can claim a territory and mate. The well-ordered social system has probably contributed to the success of the species. Large bulk with consequent low predation and year-round reproduction have favoured a territorial organisation. Territoriality regulates reproductive competition but not population growth. For management purposes it is recommended that population expansion be controlled without major social disruption by confining removals to certain 'vacuum' zones.