By Rob Edwards
A new highway could block for ever the migration across East Africa of more than one million widlebeest and zebra, a Scottish university scientist warns
The Tanzanian government is pushing ahead with plans for the new road across the giant Serengeti National Park. But Dr Grant Hopcraft, from the University of Glasgow's centre for population and ecosystem health, says it will disrupt a mass migration of animals regarded as one of the most spectacular sights of the natural world.
Every year more than one million wildebeest, also known as gnus, and 250,000 zebra, move hundreds of kilometres across vast grasslands and woodlands in search of food and water.
En route, some are killed by lions on the plains or eaten by crocodiles as they cross the Mara River in the north. The migrations have featured in acclaimed nature documentaries.
But now they are facing a new threat from humans. The planned road, which could carry as many as 3000 vehicles across the Serengeti every day, would cut straight across their path.
Hopcraft is in no doubt about the damage this would cause. "A road would have catastrophic effects on how these animals migrate," he said.
"It would separate their dry-season refuge from their wet-season calving grounds. All 1.3 million wildebeest and 250,000 zebra would have to cross that road in order to access the Mara River, which is the only source of water during the dry season."
The road is designed to create a trade route from Dar es Salaam and other Indian Ocean ports to Lake Victoria, Uganda, Kenya, Burundi and Rwanda.
It has been a heated source of controversy between conservationists and the Tanzanian authorities for decades.
In June, the East Africa Court of Justice ruled that constructing a tarmac road from Loliondo-Kleins Gate to Mugumu would be "unlawful" and "could cause irreversible damage to the property's outstanding universal value". But it left open the possibility of building a gravel road.
Last month, East African Business Week reported that local authorities in Arusha in Tanzania were pressing for the road to go ahead. "We shouldn't be discouraged by anyone. We need to continue with our plans," said Monduli district commissioner Jowika Kasunga.
"The big fear is that, although the court judgement rules against a tarmac road, an improved gravel road - which could be almost as environmentally damaging - is not precluded," said Dr Chris Magin, who co-ordinates work in Tanzania for the Royal Society for the Protection of Birds.
"If allowed to go ahead, this would be a road to ruin for one of the world's greatest wildlife spectacles, disrupting the Serengeti's famous mass migration and slicing up a pristine ecosystem."
Along with colleagues from Germany, Argentina, Australia, Canada, The Netherlands and Tanzania, Hopcraft has just published a study into the influences on migration patterns of wildebeests and zebras. Over the past 10 years 40 animals have been fitted with collars that use satellite and mobile phone technology to track their movements.
The results show that by far the biggest factor in the choice of migration routes is the need to avoid the threat of humans and human developments. "The impact of humans trumps everything else," said Hopcraft.
"This provides critical insights as to why other migrations are collapsing," he suggested. Numbers of saiga antelopes migrating across the Mongolian Steppes, pronghorn antelopes moving across the US state of Montana, and caribou and bison migrating across North America have all been declining.
"There are only a handful of places left in the world where animals can still migrate, and in these locations many of the populations are declining at an alarming rate," he added.
"The Serengeti is one of the last strongholds and even this ecosystem is threatened by humans, despite its World Heritage status."
Zebra and wildebeest are also under threat from poaching, with some evidence suggesting that as many as 80,000 wildebeest are illegally hunted every year for the bushmeat trade.
"When these animals encounter areas of high poaching, both species attempt to exit the area as soon as possible by moving a long way and in straight lines, regardless of the food," said Hopcraft.
"It appears as though they can detect risky areas and respond accordingly, which means if we want to protect migrations we need to focus on managing humans and not the animals."
He added: "These intact ecosystems where natural processes such as migrations have occurred for thousands of years serve as a critical benchmark against which we can measure our own impact."
About 150,000 adult wildebeests are killed every year by predators and through poaching, accidents and starvation.
Their young are unusual in that they are born with the ability to run, with most starting to run within an hour of birth.
The Tanzanian government did not respond to requests to comment from the Sunday Herald.