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This Photo Of Dead Wildebeests Isn't As Shocking As It Looks

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Astonishing photos published at Africa Geographic show hundreds of wildebeest dead in the Mara River in northern Tanzania.

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Safari365

It's a dramatic image. But here's the kicker: It's normal.

Or at the very least, not uncommon. Thousands of wildebeest die during their annual Serengeti migration when they move 1,200 miles from Tanzania into Kenya and back every year, according to Richard Estes, esteemed wildebeest expert and author of the book "The Gnu's World."

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Safari365

"Many die crossing the Mara River," Estes told The Dodo. Estes, who is also a research associate at the Smithsonian Institution, began studying wildebeest in 1962. "They die all over the range, but the Mara is where thousands of wildebeest (gnus) converge. It is also where thousands of tourists go to view and photograph the crossings."

"In fact," Estes notes, "sometimes so many tour vehicles line up along the banks, they block the wildebeest who have crossed from the other side."

There are some 1.25 million wildebeest in the region, according to Estes. Although the mass drowning of animals makes for astonishing images, the annual birth of up to a quarter-million calves, he explains, offsets all the losses and keeps the wildebeest numbers robust.

When the migration begins and ends is determined by one thing only: the rains. "The migration changes depending on the season. It isn't consistent. When the rains stop around May, [the wildebeest] start their migration from Tanzania and usually arrive in the Masai Mara in Kenya by July," says Estes.

Wildebeest movements are led by adult males, says Estes."They share gender traits with humans: the males are bolder; the females, on whom offspring survival depends, are more cautious." When a movement of some thousands of wildebeest encounter an obstacle, such as a stretch of dense woodland or a river crossing, there is a traffic jam. The bulls don't know one another individually. They look at each other and say, 'Hey, you go. No, you go.' The slightest disturbance may send them all running back the way they came. Eventually some one takes the plunge -- often a herd of zebras or even a little gazelle -- and then they all jump in."

Wildebeest crossing the Mara River. (Paul Khurana)

Wildebeest crossing the Mara River. (Paul Khurana)

Safari365There are more consistent, salient threats to wildebeest than natural events, including poaching and efforts to build a Serengeti highway and railway system, which would bisect the migration, he notes. But, Estes says, the main threat to survival of the Serengeti ecosystem is the increasing human population. "It is growing at a rate or 2-and-a-half to 3 percent a year. Whether the Serengeti ecosystem can remain intact through this century depends largely upon stopping encroachment by the burgeoning human population along its borders." The Serengeti migration enters the Kenya Mara, the wettest part of the ecosystem, to graze still-green pastures and because the Mara River is the only perennial stream in the Serengeti ecosystem (access to Lake Victoria is presently inaccessible), says Estes, which highlights its astounding importance. Sadly, he says, the river's flow is being reduced by deforestation of its headwaters on the Mau Escarpment and withdrawal of water for irrigation development upstream from the Reserve. "If an extended drought should cause the river to stop flowing, up to 100,000 wildebeest and zebra could die in the first month! The whole population would crash in short order marking the end of the Serengeti migration," he adds."The whole world should invest in safeguarding the Serengeti," says Estes. "Governments, NGOs, scientists, and citizens who care about the future must be vigilant to counter threats to continuation of this last and greatest of all Africa's migratory savanna ecosystems."Update: This post has been updated to include additional information from Richard Estes.

There are more consistent, salient threats to wildebeest than natural events, including poaching and efforts to build a Serengeti highway and railway system, which would bisect the migration, he notes. But, Estes says, the main threat to survival of the Serengeti ecosystem is the increasing human population. "It is growing at a rate or 2-and-a-half to 3 percent a year. Whether the Serengeti ecosystem can remain intact through this century depends largely upon stopping encroachment by the burgeoning human population along its borders."

The Serengeti migration enters the Kenya Mara, the wettest part of the ecosystem, to graze still-green pastures and because the Mara River is the only perennial stream in the Serengeti ecosystem (access to Lake Victoria is presently inaccessible), says Estes, which highlights its astounding importance. Sadly, he says, the river's flow is being reduced by deforestation of its headwaters on the Mau Escarpment and withdrawal of water for irrigation development upstream from the Reserve.

"If an extended drought should cause the river to stop flowing, up to 100,000 wildebeest and zebra could die in the first month! The whole population would crash in short order marking the end of the Serengeti migration," he adds.

"The whole world should invest in safeguarding the Serengeti," says Estes. "Governments, NGOs, scientists, and citizens who care about the future must be vigilant to counter threats to continuation of this last and greatest of all Africa's migratory savanna ecosystems."

Update: This post has been updated to include additional information from Richard Estes.