One of the lions before it succumbed to the poison
Environmentalists in Kenya are worried that an insecticide is being used by farmers to kill lions and other predators.
Carbofuran is a very powerful and toxic insecticide.
Spread in the soil, it destroys bugs in the ground and is taken up by plants and kills insects which feed on the sap or foliage.
It is so powerful and toxic that it has been banned in Europe.
In the United States it cannot be used in granular form, and the US Environmental Protection Agency is seeking a total ban.
But in Kenya, carbofuran can be bought across the counter without restriction.
According to world-famous naturalist Dr Richard Leakey, it is being bought not by farmers wanting to control bugs and insects, but mainly by herdsmen who use it to kill lions, leopards and other predators.
Among the latest incidents two lions were poisoned and killed in the Maasai Mara game reserve after eating the carcass of a hippo that had ingested carbofuran.
Vets and wildlife rangers were called to watch the pathetic sight of the lions staggering and weakened from the effects of the poison.
(Carbofuran has) become known in rural communities in Kenya as an easy way to get rid of predators
Naturalist Richard Leakey
One of the lions was shot to bring a quick end to its suffering.
Another lion died a few months ago from carbofuran poisoning on a private ranch in Laikipia.
In November last year, a dead camel was apparently found laced with carbofuran near Lewa Wildlife Conservancy.
The result was the death of at least two lions and 15 vultures which feasted on the carcass.
Also near Lewa, several lions from the nearby Samburu Wildlife Reserve were poisoned; again, it is thought carbofuran was responsible.
There are many other cases throughout Kenya of predators dying after eating meat contaminated with the chemical.
Dr Leakey says carbofuran is "deadly poisonous" and he has called for it to be banned in Kenya.
"It's become known in rural communities in Kenya as an easy way to get rid of predators: lions, leopards and hyenas," he says.
Dr Leakey says his research shows that Furadan, the trade name of the biggest-selling carbofuran insecticide in Kenya, is being bought not by farmers but by pastoralists who do not have any land for growing crops, and use the chemical to kill lions and leopards which threaten their herds.
There is no record for the number of predators killed in Kenya by poisoning, but many naturalists believe carbofuran is responsible for thousands of deaths, not just of big cats but all carrion eaters.
I literally saw vultures dropping out of the sky
Vulture expert Simon Thomsett
Simon Thomsett, a world renowned expert on vultures, eagles and other birds of prey, says there has been a "dramatic drop-off in the number of birds of prey in the past few years", and the finger of blame is being pointed at carbofuran.
He gives the example of 187 vultures that died when they fed on a carcass of an animal that was apparently laced with the deadly poison in an area by the Athi River.
Simon Thomsett says the poison cannot be detected when sprinkled on the carcass and is very fast to act.
"I literally saw vultures dropping out of the sky just a few minutes after they had eaten the poisoned meat," he said.
Easy to buy
Carbofuran comes in granular form, tiny dust-like purple pellets.
I went into several agricultural merchants in the capital, Nairobi, and found it easy to buy.
Vultures have died after feeding on laced carcasses
Three shops said it posed no health threat to animals or humans.
"It's safe, it's perfectly safe," one shop assistant told me.
Others warned it was poisonous and one shop-keeper even described carbofuran as a "lion-killer".
The container warns that it should be kept "locked away out of reach of children", but there is not a word on the label about a potential threat to wildlife.
Kenya's Pest Control and Products Board is carrying out research into carbofuran's dangers and toxicity, and say it is too early to come to a conclusion.
Dr Leakey says the evidence is there for all to see.
His worries are shared by Thomas Manyibe, a vet with the Kenya Wildlife Service who carried out post-mortem tests on the lions that were killed in the Masai Mara.
He says evidence shows that carbofuran is being used to target lions and leopards.
I spoke to pastoralists who said they had heard that Furadan was used to kill big cats.
On the edge of the Maasai Mara a young herdsman, Ndigwa, said he lost many cows every year to lions and leopards, but he said he would never resort to poison to take revenge on the predators.
We take stewardship of our products very seriously and condemn any intentional baiting misuse of carbofuran
The Masai on the escarpment above the Mara reserve know that a healthy, abundant population of predators is important to their livelihoods, derived in part from income from tourists coming to watch the game; and there is no suggestion at all that they have been involved in trying to poison lions.
Others do not hesitate.
Carbofuran comes from a number of different overseas suppliers, but the main producer is the US firm FMC Corporation.
The company said in a statement: "We take stewardship of our products very seriously and condemn any intentional baiting misuse of carbofuran.
"FMC is very concerned about reports of carbofuran (Furadan) being used to bait lions in Kenya and we have offered our services to the Kenya Pest Control Products Board in their investigation."
Concerns about the use of carbofuran are not new.
Fifteen years ago there were a number of cases of mass killings of birds in western Kenya; what is lacking is a comprehensive record of predators killed by poisoning.
There is lots of circumstantial evidence but few hard facts.
Detailed information is elusive, affected animals often disappear into the bush to die, and the evidence is then eaten by other carnivores.
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