Black rhinos, once relatively common in northern Botswana, were drastically reduced in number by past hunting and more recently by poaching activities. Less than 20 individuals were suspected to occur within the region in 1968 (Smithers, 1971), and even fewer towards the end of the 1980s (Potgeiter & Walker, 1989).
A total of seven white rhinos, in four groups, were counted during the survey. Two individuals (an adult male and female) were found in northern Moremi Game Reserve, while the remaining five animals (two adult females, one unsexed subadult and two unsexed immature individuals) were located in eastern Chobe National Park. A single fresh white rhino carcass was also located in eastern Chobe, from which the horns were noted to have been removed. The few sightings of white rhinos confirm that the population in northern Botswana is at an extremely low level. From the present survey and other sporadic reports during the survey, Hitchins (1992) estimated the white rhino population in Moremi and northern Botswana to be about 27 individuals. This estimate is about 13 % of the expected population size of about 216 animals since reintroduction, that is with normal recruitment and the total absence of poaching. The presence of a freshly poached white rhino found during the survey reiterates the danger that this small population is on the brink of extinction, albeit for the second time in Botswana. The urgency of the situation resulted in a capture and relocation programme of four white rhinos from eastern Chobe to a safe, fenced sanctuary elsewhere in Botswana. However, the fact that one of the animals subsequently died from bullet wounds inflicted by poachers prior to the capture operation further emphasises the seriousness of the poaching threat facing this and other rhino populations in the rest of southern Africa.
White rhinos became extinct within Botswana by the end of the 19th century through hunting activities (Bryden, 1893). Through a reintroduction programme between 1967 and 1981, a total of 71 white rhinos were successfully re-established m Chobe National Park and Moremi Game Reserve in Botswana from Natal, South Africa (Hitchins, 1988). However, owing to recent poaching activities the population has again been greatly reduced (Gavor, 1988).
Although the Botswana population was considered a separate subspecies D. b. chobiensis, based chiefly upon skull morphology (Rookmaaker & Groves, 1978), preliminary mitochondrial DNA analyses have revealed a closer affinity with the south-central ecotype D. b. minor than with the more arid-adapted southwestern ecotype D.b.bicornis (Harley, 1990), recognised by the African Rhino Workshop (Cincinnati, October 1986). Nonetheless, given the slight morphologial differences found in the Botswana population, the conservation of this genetic stock would be advantageous for the sake of preserving genetic heterozygosity until further definitive taxonomic work can be undertaken.
