ONLY weeks after South Africa was given permission to sell a few of its 鈥渟urplus鈥� white rhinos, a row has blown up over the population figures that were used to justify the decision.
At the biannual meeting of the Convention on International Trade in Endangered Species, which took place in Fort Lauderdale in November, South Africa asked if the ban on all trade in white rhinos could be lifted so that it could sell some live animals to nature reserves and some to game farms where they would be hunted for trophies. The meeting heard that South Africa has a wild population of around 6300 white rhinos of which some 2000 were said to be in the Hluhluwe-Umfolozi Game Reserve in Natal, the world鈥檚 most important white rhino reserve.
This figure was calculated from a population survey carried out in 1991 using the 鈥渓ine transect鈥� method, in which an area is divided into sections that are systematically surveyed on foot and the data analysed according to a statistical formula. But field staff working for the Natal Parks Board have long considered this estimate to be too high, and in September and October they made a new estimate, this time carrying out a survey from the air as well as a line transect.
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For the aerial survey, the whole park was inspected thoroughly from a helicopter. The team came up with a count of 1210 white rhinos. This figure, which suggests that the reserve may have 40 per cent fewer rhinos than officials have been claiming, was not made public nor discussed at the CITES meeting when South Africa鈥檚 request for limited trade in rhinos was being debated. When the figure was leaked to the press, it caused a flurry of claims and counter-claims about the significance of the count and whether it should have been disclosed at Fort Lauderdale.
鈥淎s the low count was a preliminary air count without ground checking it didn鈥檛 occur to us to either talk about it, or not to talk about it,鈥� says George Hughes, chief executive of the Natal Parks Board.
Aerial surveys are 鈥渘otoriously variable鈥�, he says: at best this survey represents only the minimum number of white rhinos in the park. No conclusions can be reached until the results of the line transect are available next month, he says.
However, Peter Hitchens, an independent rhino specialist and experienced aerial surveyor who conducted the count, defends his results. 鈥淭he conditions were ideal, and we had very good observers in the aircraft who all knew the reserve well,鈥� he says. Allowing for the fact that an aerial survey always misses some animals, Hitchens believes his count is accurate to within 100 animals. It tallies, too, with the gut feelings of field staff who say the scientists at head office do not know what is going on in the park.
Whatever the final figure turns out to be, officials at the Natal Parks Board concede it is likely to be several hundred short of 2000. Some conservationists support the board鈥檚 view that it is not the actual numbers that are important, but population trends. And the available evidence suggests that the white rhino population is increasing. It was on this basis, they say, that CITES was persuaded of South Africa鈥檚 need to trade 鈥渟urplus鈥� animals to avoid overpopulation in the rhino reserves.
But Clive Walker, chairman of the Elephant and Rhino Foundation, says that head counts cannot be dismissed when the animal concerned is so severely threatened throughout the continent. The revised estimate could indicate a population decline of nearly 10 per cent. 鈥淲e鈥檙e at a stage in Africa where we need to know exactly how many animals we鈥檝e got if we鈥檙e to preserve them.鈥�