Animals of the michaeli subspecies were introduced from Kenya in the early 1960's. Unfortunately, there minor bulls were added in 1977 which created the problem of genetic mixing of subspecies. However, it is relatively easy to distinguish rhinos of the two subspecies from the air and from the ground - minor animals are smaller and have a smoother skin than do michaeli animals. In May 1981 two minor bulls were removed (the third had earlier been castrated) and in May 1983 three hybrid calves were captured and sent to the National Zoological Gardens (Pretoria). Today, Addo holds 14 pure michaeli rhinos (and one castrated minor bull), comprising five males and nine females: four of the females are adult cows and all have calved within the last four years. Thus, the prospects for reproduction and population increase are very good. All rhinos are inside the elephant-proof fence, the habitat for them is excellent and the area available will soon be enlarged to 6 800 ha. The National Parks Board has agreed to maintain the genetic purity of this population.
When the Kruger Nationial Park was proclaimed in 1926 only 4 or 5 black rhino remained, and by 1940 the species was extinct. Reintroduction began in 1971 with 20 animals from Zululand, and 12 in 1972 from Rhodesia (now Zimbabwe). By 1982, 70 animals had been moved to the Kruger National Park, including two in 1981 from Addo (these two had originated in Zululand and were both minor). The sex ratio of these introductions was 38 males to 32 females. Animals have moved up to 70 km from their release point, with subadult males moving the furthest. Recruitment rate is about 9 % p. a. and there is on average one immature animal with every adult female. The population comprises about 39 % immatures - this is a `young' and expanding population. By end-1983, the total population was estimated at 104 (Hitchins had estimated 113). At a density of 0.19 animals per km? , the Kruger Nationial Park could hold 3500 animals in suitable habitat. The population west of Skukuza is `fairly dense' at 0,19 per km?. The Kruger Nationial Park and two reserves in S.W.A. (Etosha could carry 1000 and Bushmanland 500) are the only places in the R.S.A and S.W.A. that could therefore hold a genetically viable population if this is one holding a minimum of 500 animals. The Kruger National Park rhinos are genetically `mixed' as they originate from Zululand (mostly) and Zimbabwe, in the proportion of 57 to 13 of the initial introductions. However, once upon a time the rhinos of these two areas were genetically continuous and so a mixing in the 1970's in a third area is not foolish. [In fact, artificially keeping them apart would rather be considered foolish - Collinson].
By 1896 the white rhino was extinct in the Transvaal lowveld. The last sighting was near Skukuza in the year before. In the 1960's, 141 animals were introduced, followed by another 204 in the early 1970's. All animals were followed up for at least 24 hours - some eventually settled up to 70 km from their release point. A `pool' of known-aged animals in the Pretoriuskop area has been watched by T. Mostert, and these observations have provided very useful data. For example, of 27 births the sex ratio was skewed to two males to one female. Over the years, the juveniles have comprised 5,5% - 13,9% of the population, with 8% in 1983 in the southern district of the Kruger National Park. Here, a local overpopulation may soon occur, and animals could then be removed to the northern regions. By late 1983, the total population was estimated at 749. The animals now occupy a range of about 4500 sq.km. The translocation has been a success to the extent that by the year 2000 we expect to be culling white rhino!
