The decomposing carcasses were discovered on a farm at Fort Rixon, about 370 kilometres from the capital Harare, according to Kerri Wolter, from vulture conservation group Vulpro in South Africa.
The birds – most of them endangered white-backed vultures – appear to have died after feeding on a cow carcass laced with cyanide or aldicarb, which are both fast-acting poisons.
First reports suggested the vultures were victims of a farmer trying to rid his land of predators such as jackals or hyenas rather than poachers, who have been blamed for fuelling the decline of vulture populations in southern Africa over the past few years.
The sight of vultures congregating high above the African bush is a sure sign of a recent kill. But the scavengers are hated by poachers because they alert rangers to their presence. Poachers lace the carcasses of elephants and other game with cyanide or pesticides such as temik so the birds die before they can take to the skies again.
The practice gives the poachers time to saw off tusks and disappear into the bush. It has contributed to devastating declines in vulture populations in Zimbabwe, Namibia and South Africa, where the numbers of some species have fallen by 50 to 80 per cent.
Farmers who use poisons are also to blame. Ms Wolter said: “We have a combination of poisoning from poachers and farmers and both are as detrimental.”
Zimbabwean conservationist Clive Stockil, who has worked in the southern Save Valley Conservancy for decades, said: “While there probably still are more vultures than rhinos, the hunting and killing of a rhino is very specialised and will kill one or two rhinos at a time. There have been cases of several hundred vultures being killed in one incident. This has the potential of bringing the vulture population to extinction.”
Mr Stockil, who was presented with a Tusk Lifetime Achievement Award by Prince William last year, said vultures were now “more threatened than rhinos”.
In Zimbabwe’s Gonarezhou National Park 184 vultures were killed in 2012 when an elephant carcass was laced with temik, a pesticide sold as rat poison.
Last year researchers in the park found only five active lappet-faced vulture nests, down from 40 in the 1970s.
Figures for the total population of the eight vulture species that occur in the region are almost impossible to obtain. Vulpro said there are 3,800 breeding pairs of Cape Griffons, among the most vulnerable. There are about 25,000 rhinos left in Africa.
The dead vultures included two Cape Griffons, three lappet-faced vultures and 39 white-backed vultures.