The carcasses of wildebeest rotting since last week are being picked over by Maribu storks, vultures, crocodiles and other scavengers.

Some visitors clutch handkerchiefs to their faces to cope with the smell as they take pictures of the pileup of corpses.

"It was a strong tide that swept them away," said Mara administrative official, Sarisa Nkadaru, adding that most wildebeest died when they were stepped on by others.

Some officials blame the destruction of the nearby Mau forest for changing weather patterns and affecting tide levels, and they called on the government to curb the deforestation.

"Had the forest not been destroyed, the speed of water in the river would have been checked and the wildebeest would not have been swept away," local conservationist Doris Ombara said.

"We have raised alarm over the dangers of the destruction and what was witnessed last weekend is one of them," she said.

But fears that tourists would be put off by the deaths were rejected by the reserve's senior game warden, Michael Koikai. He said that although 15,000 was a huge loss, it was still a tiny percentage of the total.

"This incident happened while peak season is still on, but it has not affected it as there are more than 5 million wildebeest in the Mara-Serengeti eco-system," Kokkai said.