Tourists to Blame?
Tourists come by the thousands to witness the wildebeest's annual migration through the Mara Reserve (see a video about the wildebeest migration).
KWS actively encourages tourism, and indeed the mass deaths threatened to pose a public relations problem that could drive tourists away.
But in its report, the agency says that sightseers on safari may themselves have played a role in the deaths.
Crowding caused by vehicles full of wildlife-watchers may have forced the animals from their preferred crossing point and sent them to a less auspicious spot, officials say.
"It's something the tourists do, they flock to this [crossing] point," Omondi said. "In other years they flock [to this point], then if the wildebeest move a distance of five meters from the crossing point, it makes no difference.
"But this time there was a lot of water, so that could have been one of the factors—tourists flocking and having a lot of water could have led to the extra deaths that we saw."
Conservationists who witnessed the wildebeest pileup, however, contradict KWS's account.
"There was no tourist interference that made the wildebeest cross where they did," said Terilyn Lemaire, a Mara Conservancy conservation worker who saw the event and first reported it on her blog.
"In fact, they crossed in an area that was not even viewable by vehicle and that was far from the usual crossing point, [called] Omega.
"Tourist vehicles always have the potential to interfere, but here in the Mara Triangle, the Mara Conservancy's rangers diligently ensure that tourist vehicles are constantly kept at a distance that ensures crossings are not impeded."
Lemaire added that she stands by her group's count of 10,000 dead.
Killing the Mara With Tourism?
Whether or not tourists contributed to the wildebeest deaths, the event has raised the question of how many tourists are too many in the Mara.
"[Death] is a feature of the [wildebeest] migration and a feature of huge numbers crossing at a bottleneck," said Richard Estes, a Harvard professor and one of the world's foremost researchers on wildebeest.
"This can happen without human interference, but one of the points that I think is relevant is they're killing the Mara with tourism," Estes said.
"Building more and more camps, going in more and more vehicles, [tourists and safari operators] are not being properly supervised, prevented from [doing] stupid things like blocking a crossing. It's happening more and more."
KWS says it is working to confront the growing pressures posed by tourism. The agency is in the middle of a management review to see if its current plans for the Mara are working, officials said.
"The [tourist] levels are still OK," said chief Mara warden Michael Koikai. "The problem is you have tourists concentrating in southern pressure points, and that is what's causing degradation.
"They congregate in specific areas where, for example, carnivores feed, and that is what causes animals harm and vegetation destruction."
"The problem is all minibuses are equipped with radios, and once one person sees a lion or a cheetah, they call other minibuses and all congregate at a particular point."
Nonetheless, some observers say there's no need to debate why the wildebeest died or what might be learned from the event.
The deaths, like most in the Mara, were simply an unpreventable and natural event, they say.
"There's a whole lot that die and things like this, but it shouldn't become such a big problem," said Johann du Toit, a professional safari guide.
"People are making a mountain out of an anthill. Sometimes you have a bad drought and everything dies, and sometimes you don't. It's all part of a natural cycle."
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