Visitors entering the lowveld through the J G Strijdom tunnel can enjoy the majesty of the mountain pass with their naked eye. A good pair of binoculars focussed on the cliffs a few kilometres down the road may reveal an unusually white section of rock – the home of the third largest colony of Cape vultures in South Africa, on Manutsa Ranch. Cape vultures make up only a small proportion of the vultures seen in the Kruger National Park, and the majority of the birds seen are sub-adult or non-breeding.
Since there are no cliffs suitable for Cape vulture colonies within the Kruger National Park, the Manutsa colony is a likely source of the birds sighted in Kruger. Orpen Gate is about 80km away as the vulture flies. However, these large birds have been recorded as travelling distances of over 1100km, and the vultures seen in Kruger could easily have made an international arrival.
Cape vultures are on the decline within their distribution, and the Manutsa colony has lost almost a quarter of its breeding pairs in the last two decades. However, this colony appears to be doing better than the two larger colonies of Kransberg (in Marakele National Park) and Blouberg (in Blouberg Nature Reserve). The colony is located on private land, and landowner Richard Anker-Simmons has made it his mission to ensure the colony is left as undisturbed as possible. “We have discouraged the South African Air Force from flying too close and not allowed catching and ringing of nestlings for over 20 years.”
The colony is monitored by Dr Patrick Benson from the University of the Witwatersrand. Over a period of 12 years, starting in the 1980s, four helicopter flights were made along the cliff to photograph existing and potential nesting sites. The photographs were turned into a map of the nesting sites, and now telescopes are used to monitor activity in the colony. There are currently about 450 active nesting sites. The colony was declared a Natural Heritage Site in 1989. Various reasons have been put forward for the decline of the Cape Vulture, including the use of poisons, mainly by farmers trying to get rid of ‘problem animals’.
This type of poisoning has declined, but Cape vultures are among the vultures used by the muti trade, which has been known to get vultures through poisoning. Communal areas where high stocking rates and overgrazing occur may provide a rich food source for the vultures. Dr Benson has noted that the largest colonies are all close to former homelands. Improved farming practises in these areas means less food for the vultures. Cape vultures can eat 1.5kg at a sitting, which is over 15 percent of the weight of an adult bird. They can do this in five minutes, other vultures permitting. However, the large size of the birds means that they need a stiff breeze or a long runway to launch themselves into flight after feeding on a carcass.