Felix Borner

Olivia Judson on the influence of science and biology on modern life.

Imagine. You are lying in the grass in the east African savannah, watching wildebeest fording a shallow river. You can hear the funny grunting noises they make, and as they pass by, you can feel the impact of their hooves on the ground and smell their rich animal smell. You see their kicking heels, their beautiful sleek bodies. Then you look up, and you realize that the herd stretches as far as you can see, that the plain is dark with wildebeest. If you were to wait for them all to pass, you would be there for days.

The sight is magnificent, primal and profoundly moving. It is the wildebeest migration.

Every year, more than a million wildebeest, along with hundreds of thousands of zebras and gazelles, move through the Serengeti-Mara ecosystem of Tanzania and Kenya, following the rains. In the course of a year, an individual wildebeest may cover as much as 2,100 kilometers. (That’s more than 1,300 miles — which is further than the distance between New York and New Orleans.) It is the last great migration on Earth.

But for how much longer? A large part of the migration takes place within the vast Serengeti National Park in Tanzania, and there are reports that the Tanzanian government is preparing to build a major road through the northern part of the park: through a designated wilderness area, through the migration route.



Roads are catastrophic for wildlife. The experiment has been done again and again all over the world: we know. Among the problems: roads allow the easy spread of invasive plant species, as car tires often carry their seeds. Roads also allow the rapid spread of animal diseases, and lead to an increase in poaching, building and other human activities.

But by far the biggest problem is that roads fragment habitats and disrupt animal movements. Many animals are reluctant to cross roads, even those with little traffic. And when there is a lot of traffic, the lives of people and animals are both at risk.

Grant Hopcraft

The usual solution is to fence the road to protect the cars. Doing this here would likely end the migration, cause the collapse of the wildebeest population — and destroy the Serengeti as we know it.

The reason is that the lands to the north of the proposed road remain wet when the lands to the south have become dry. Unable to reach the water, tens of thousands of animals would die of hunger and thirst; many would become tangled in the fence. Building the road with animal tunnels or overpasses, as has been done in Canada and other countries, would be expensive and impractical; moreover, it probably would not work, as wildebeest are sensitive to disturbance. They already avoid areas frequented by poachers, and are alarmed by cars.

And if the migration stopped, the Serengeti would cease to be the Serengeti, for the wildebeest define the ecosystem and drive its dynamics. The migration is the reason the wildebeest are so numerous: it allows them to transcend the limitations imposed by local supplies of food, water and predators. And in their travels, the animals spread nutrients throughout the system. They fertilize plants with their urine and dung, and trample the soil. By doing so, they help to maintain a diverse array of plants, insects and birds, and are themselves food for large numbers of lions and hyenas.

Wildebeest also help to maintain large numbers of humans. Tourism accounts for 8 percent of gross domestic product in Tanzania, and more than 600,000 jobs. If the migration stopped, tourism would likely decline. After all, there would be much less to see.

Good roads are, of course, an important part of economic development. They connect isolated communities, and allow for the trucking of commodities between inland areas and port cities. One of the challenges of conservation is balancing the needs of humans today while protecting the resources of tomorrow.

Felix Borner

But the peculiar thing about this road is that it is not a case of animals versus people. There is an alternative — a road to the south of the park that would connect five times more people, and cost less to build. It would also be easier, since the landscape there is flatter; and it would not affect the animal migrations. And the northern road has been vigorously rejected on environmental grounds before.

Even more peculiar: up to now, the government of Tanzania has had an outstanding record of conservation. Around a quarter of the country’s area is managed with a view to preserving wildlife, and at 50,000 square kilometers (almost 20,000 square miles) the Selous Game Reserve is the largest protected area in Africa. Tanzania boasts seven UNESCO World Heritage Sites, of which four are nature reserves — including the Serengeti National Park.

Moreover, the president of Tanzania, Dr. Jakaya Kikwete, is known for his interest in nature. When six black rhinos arrived in the Serengeti in May — they were flown in from South Africa as part of a rhino relocation program — the president himself was there to meet them, and he has often spoken of the importance of the parks to Tanzania. Indeed, he sometimes quotes Tanzania’s first president, Julius Nyerere:

“The survival of our wildlife is a matter of grave concern to all of us in Africa. These wild creatures amid the wild places they inhabit are not only important as a resource of wonder and inspiration but are an integral part of our natural resources and our future livelihood and wellbeing. In accepting the trusteeship of our wildlife we solemnly declare that we will do everything in our power to make sure that our children’s grand-children will be able to enjoy this rich and precious heritage.”

It is not clear why the Serengeti road is being considered: I was unable to reach anyone in the Tanzanian government who would comment. But what is clear is that one of the most marvelous and awe-inspiring sights on the planet might soon vanish, killed by a road.

Notes:

I was lucky enough to see the northern part of the wildebeest migration in Kenya in 1998, and I can attest that it is an amazing and beautiful sight.

The distance an average wildebeest travels in a year was communicated to me in an e-mail from Grant Hopcraft of the University of Groningen. I got the distance between New York and New Orleans from here.

A northern road through the Serengeti has been under discussion for a number of years. The route of the proposed road can be seen on a statement from the Frankfurt Zoological Society.

Evidence that the road is moving forward has come to me from a number of sources, including a copy of a letter sent by Dr. Christof Schenck, the director general of the Frankfurt Zoological Society to His Excellency Dr. Jakaya Mrisho Kikwete, President of Tanzania, on May 31, 2010; and a copy of a letter sent by Tim Clarke, Ambassador to Tanzania for the European Union, to Mr. Shukuru Kawambwa, Minister of Infrastructure for Tanzania on April 9, 2010. There have also been some press reports. One appeared in the Tanzanian newspaper The Guardian on Sunday, June 13, 2010, with the title “Government to build highway through sensitive Serengeti”; the author was Adam Ihucha. It can be read here; type “sensitive serengeti” into the search box. Another article appeared in Britain’s Sunday Express.

The northern road through the Serengeti National Park was vigorously rejected by a Norconsult study in November 1996. See the United Republic of Tanzania Ministry of Works, Technical and Socio-Economic Feasibility Study: Makuyuni – Musoma Road, Final Report. A different conclusion was reached by a more recent report by Inter-Consult, prepared for the Ministry of Infrastructure Development in November 2007. See “Tanzania National Roads Agency (TANROADS) Environmental and Social Impact Assessment, Feasibility Study and Preliminary Design for Natta-Mugumu-Tabora B-Klein’s Camp-Loliondo Road (239km) Upgrading Project” Volume 5, Environmental Impact Assessment Report: Final Report. This report recognizes that there will be an impact on wildlife, but argues (implausibly, in my view) that it can be mitigated.

The alternative southern road, along with the numbers of people it would connect and the costs of building it, is documented in a presentation called “The Serengeti North Road Project” prepared by Borner, M., Bigurube, G. and Sinclair, A. R. E. It is available here; click on “Presentation on the Serengeti Road / Alternative Routes” under downloads.

For a general overview of different ways that roads impact wildlife, including a discussion of the spread of invasive plants and pathogens, and the increased risk of poaching, see Trombulak S. C. and Frissell, C. A. 2000. “Review of ecological effects of roads on terrestrial and aquatic communities.” Conservation Biology 14: 18-30. For the overwhelmingly negative effect that roads have on wildlife, see Fahrig, L. and Rytwinski, T. 2009. “Effects of roads on animal abundance: an empirical review and synthesis.” Ecology and Society 14 (1): article 21. For the general problem of animal diseases being spread by animal transportation, see Fèvre, E. M. et al. 2006. “Animal movements and the spread of infectious diseases.” Trends in Microbiology 14: 125-131. For the general problem of animals and road deaths, see Groot Bruinderink, G. W. T. A. and Hazebroek, E. 1996. “Ungulate traffic collisions in Europe.” Conservation Biology 10: 1059-1067.

For efforts to mitigate the effects of roads by means of animal underpasses and overpasses see, for example, Clevenger, A. P. and Waltho, N. 2000. “Factors influencing the effectiveness of wildlife underpasses in Banff National Park, Alberta, Canada.” Conservation Biology 14: 47-56; and van der Ree, R. et al. 2009. “Wildlife tunnel enhances population viability.” Ecology and Society 14 (2): article 7. The fact that wildebeest avoid areas frequented by poachers was communicated to me in an email from Grant Hopcraft; the data are being prepared for publication.

For the myriad ways that wildebeest define and shape the Serengeti, see Sinclair, A. R. E. and Arcese, P. (editors) 1995. “Serengeti II: Dynamics, Management, and Conservation of an Ecosystem.” University of Chicago Press. For wildebeest population sizes being dependent on the migration and for their role in promoting species diversity see, for example, Sinclair, A. R. E. 2003. “Mammal population regulation, keystone processes and ecosystem dynamics.” Philosophical Transactions of the Royal Society of London B 358: 1729-1740. This paper also discusses the impact on the landscape of wildebeest removal — see especially table 1. For the role of migrations in promoting extremely large populations of animals, see Fryxell, J. M., Greever, J. and Sinclair, A. R. E. 1988. “Why are migratory ungulates so abundant?” American Naturalist 131: 781-798.

For other aspects of the importance of wildebeest to the Serengeti, see McNaughton, S. J. 1976. “Serengeti migratory wildebeest: facilitation of energy flow by grazing.” Science 191: 92-94; and Frank, D. A., McNaughton, S. J. and Tracy, B. F. 1998. “The Ecology of the Earth’s Grazing Ecosystems.” BioScience 48: 513-521. This last paper also shows how herbivores such as wildebeest increase the productivity of the grasslands. Ending migrations has repeatedly caused animal populations to crash; given the known importance of wildebeest for maintaining the Serengeti ecoystem, it follows that the ending the migration would alter the landscape in numerous ways.

The figures for the contribution of tourism to gross domestic product and the numbers of people employed in the tourism sector comes from the World Tourism and Travel Council; the relevant document can be found here.

Tanzania’s World Heritage Sites can be seen here. For a quarter of Tanzania’s area being under protection, see Thirgood, S. et al. 2004. “Can parks protect migratory ungulates? The case of the Serengeti wildebeest.” Animal Conservation 7: 113-120. This was also confirmed for me by data sent to me in an e-mail from Grant Hopcraft.

For President Kikwete meeting the rhinos, see the report in Tanzania’s Daily News, May 22, 2010. The quotation from Julius Nyerere comes from a document known as the Arusha Manifesto; it has regularly been quoted by President Kikwete, including at a speech to the Wildlife Conservation Foundation of Tanzania given in Dar es Salaam on June 20, 2006. It can be read here.

Many thanks to Dan Haydon, Grant Hopcraft, Tony Sinclair and Jonathan Swire for insights, comments and suggestions.