Wildebeest migration spectacle under threat from planned road

An African vulture watches wildebeest as they cross the Mara river in the Masai Mara game reserve during their annual migration Photograph: Staff/Reuters

Conservation groups say the planned road would cut off the wildebeest from the Mara river, a crucial source of water during the dry season, and would keep the animals out of Kenya Photograph: Danita Delimont/Alamy

Wildebeest are a crucial species in this ecosystem as the sheer number of animals keeps tree seedlings from becoming established, preventing forests from encroaching on the grasslands Photograph: Frans Lanting/Corbis

In addition, the animals’ dung provides fertiliser for the grass Photograph: Bruce Davidson/NPL/Rex Features

A herd of impalas. The proposed road will critically affect all the mammals that inhabit the park Photograph: Frans Lanting/Corbis

The grazing animals provide food for predators, such as hyenas, lions, cheetahs and crocodiles Photograph: Kevin Schafer/Corbis

Wildebeest stampede on the dry grassy plains on the west side of the Ngorongoro highland. The government proposes to build a 107-mile road that will directly cross the migration route Photograph: John Warburton-Lee/Alamy

This is part of a wider plan to connect the proposed new port at Tanga to Musoma on Lake Victoria via Arusha and Lake Natron’s shores Photograph: Gerald & Buff Corsi/Corbis

A herd of common zebra with a flock of cattle egrets flying overhead. If the project is given the go-ahead then construction is expected to start in 2012 Photograph: Images of Africa Photobank/Alamy

Calculations from the Frankfurt Zoological Society suggest if the wildebeest population were cut off from dry season areas, it would shrink to less than a quarter of its current size. This would likely be the end of the great migration Photograph: Tim Graham/Getty Images