For ten days rangers of the Masai Mara game reserve took food and water for the young male lion as his body succumbed to poison.

His limbs were paralysed and he was unable to protect himself from other male lions. Finally, a bite to the back of the head, and he was dead.

Conservationists in Kenya believe he was the victim of a pesticide afflicting the country's endangered lion population.

In the past month four lions in the world famous Masai Mara have been paralysed by carbofuran - used to kill insects in food crops - after feeding on a hippo carcass contaminated with the pesticide.

Environmentalists suspect that the source may have been a lodge in the reserve using the poison to keep insects away from well-heeled guests.

Richard Leakey, Kenya's most renowned environmentalist, yesterday urged the Government to follow the example of the US and Europe by banning its importation and sale.

“We believe there are significant human health concerns and environmental risks associated with using this chemical, which is widely abused because it is easily available over the counter,” he said.

The chemical first came to the attention of conservationists in Kenya during the 1990s when it killed hundreds of waterfowl.

In the latest incident, rangers spotted another young male lion that appeared to be weak.

He could only “hop”, using his back legs to push himself along. He eventually lowered himself into the shade of a thicket and had to be put down by vets. Two others survived.

Tests traced carbofuran to a patch of grass where the hippos were known to graze. Investigators are working on the theory that it was dumped by a tourist lodge.

The insecticide is legal in Kenya and available over the counter. In Western Kenya it is even used by fishermen on Lake Victoria to bring fish floating to the surface.

Exposure to the chemical stimulates the nervous system causing headaches, nausea, dizziness, blurred vision, confusion and muscular weakness. It can result in cardio-respiratory paralysis and death.

Paula Kahumbu, conservation director with Wildlife Direct, said it was being used increasingly since controls on strychnine were tightened. In some cases lions were not the intended victims, she said, although Masai herders were using the poison to protect their cattle and goats.

“They could build barriers and dogs to keep the lions away,” she added, “but it is a lot cheaper and easier to lace a cow carcass with Furadan, which can take out an entire pride at night.”

She said Kenya's 2,000-strong population of lions was suffering badly as humans moved into wilderness areas.

The poison affects scavengers such as vultures and other birds of prey as well as large predators.

Simon Thomsett, a conservationist, said: “If the current level of usage continues, it is possible that two different species of vultures in Kenya could go extinct within the next ten years.”

Professor Vasey Mwaja, general manager of Juanco SPS, which imports carbofuran under the trade name Furadan from the US, where it is manufactured, said he doubted whether a hippo could consume enough of the poison to kill it and dismissed calls for a ban.

“The product works well and safely for farmers,” he said. “Problems come when it is being used illegally but we have no control over that.

“That said, we are already working with conservationists and the Government to ensure it is used safely.”

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