Found throughout the deciduous woodland and savanna zones of eastern, central and southern Africa, the impala is probably the most successful of all African antilope species. Fossil evidence shows that they have remained almost unchanged, with only one species of impala present in the fossil assemblage at any given time, while the closely-related alcelaphine antelopes (eg. kongoni and gnu) have split at least 18 times into new species since they evolved from impala or springbok-like ancestors like common ancestor some 8 million years ago

In addition to this evolutionary fairytale, the sleek and graceful impala can also boast a phenomenal ecological success story. Despite the ongoing environmental degradation in Africa due to human intervention, impala have in effect increased in numbers and broadened their range over the past century. Thus impala enjoy the fortunate status of being "common", to the extent that in Zimbabwe they are referred to as"Zambezi goats". And in South Africa the common impala (A. melampus melampus) is the most abundant ungulate. Its being so widespread can be attributed to its remarkable skill to adapt to a wide range of climatic and ecological scenarios. There are, for example differences in the timing of births between eastern and southern impala, which may reflect geographical differences in the timing of rainfall. In southern Africa with rain there being confined to one period each year, ninety per cent of lambs may be born within three weeks at the start of the rainy season. In East Africa, by contrast, with chances of rain for most of the year, lambs born in almost any season have some chance of being weaned onto good food. Moreover, as mixed feeders, dependent neither on graze nor browse to survive, impala are extremely flexible in their diet, which in turn has freed impala to disperse into ecotone habitat - the transition zone between open grassland and closed forest habitats, which have increased with the spread of human agricultural practices, enabling impala to broaden their range.

The black-faced impala - endangered

Set against this background, the concept of an endangered impala species seems inconceivable. As it is, of the possibly six subspecies of impala, the black-faced impala (A. melampus petersi ) is endangered. (IUCN Red Data Book)

The black-faced impala has a total population of only 3200 restricted to the arid, drought-prone, mountainous landscape of the Kunene River in Namibia's Kaokoland and southwestern Angola, in addition to Etosha National Park in Namibia where some 260 animals where translocated from Kaokoland in the 1970's, with the current tally showing at least 1500 animals. Larger and darker than the common impala (in addition to having the characteristic black strip from the top of the head to the nostrils and a longer and bushier tail with a white underside used by males for "tail flagging" during the rutting season), the black-faced impala is threatened not so much by poaching or habitat destruction, but by haphazard translocations of the common impala into the habitat of the black-faced impala, resulting in interbreeding. At the time black-face impala were introduced to Etosha NP, several small populations were also sold to commercial farmers throughout Namibia in a bid to increase the subspecies' range and abundance. At around the same time, however, common impalas were being translocated in large numbers from South Africa to Namibian commercial game farms, thus closing the 800 kilometers of the species' natural separation. With consequent hybrids now in abundance on numerous Namibian farms (including those bordering Etosha), the purity of Namibia's black-faced impala is under serious threat. Namibia's Ministry of Environment and Tourism has thus proposed that common impala-free zones be established around the ranges of the black-face impala. Farmers may, however, be reluctant to replace their stock of common impala with the black-faced impala, due to the latter's high price tag (N$ 5600) and endangered status, preventing their use as hunting trophies. Reduced prices for selected farms have been suggested as the solution.

Sources:

Tammie Matson (2002): Endangered impala. In: Africa Geographic. March 2002 issue

Michael Mooring (1999): Impala - the living fossil. In: Africa Environment and Wildlife. September/October 1999 issue

Jonathan Kingdon (2001): The Kingdon field guide to African mammals. London: Academic Press