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Epic Animal Migrations Could Change with Global Warming

When climate changes food security, it may also change the migration patterns of zebras and other wildlife
animal migration


The prevailing theory of migration says that as the availability of food decreases, animals will take more risks to obtain it.
Credit: Marc Veraart via Flickr

Avoiding people is the top priority of wildebeests and zebras making their annual migration across Africa's Serengeti-Mara, finds a new study that aims to understand how animals make decisions as they travel across the ecosystem.

With the help of 40 GPS and cellphone-outfitted animals over the past decade, researchers discovered that herds are willing to avoid food if it means escaping the detection of humans. Wildebeests and zebras alike went farther out of their way to dodge people than to avoid even animal predators like hyenas or lions—decisions that appear to be profoundly affecting their migration patterns.

The prevailing theory of migration says that as the availability of food decreases, animals will take more risks to obtain it, the study notes.

And that becomes worrisome as climate change drives up global average temperatures and causes precipitation patterns to shift.

"If these animals are tracking rainfall patterns, which we know they are, then climate change could mean a fairly substantial change to their migration pattern," said Grant Hopcraft, a research fellow with the University of Glasgow's Boyd Orr Centre for Population and Ecosystem Health, who led the project.

But the addition of humans appears to change things. "As soon as you put humans into the equation, their behavior changes immediately," Hopcraft said.

Noting that 80,000 wildebeests alone are illegally poached for bushmeat annually, he said, "The risk of dying from humans is worse than dying from lions in the Serengeti." As climate change has altered conventional agriculture, the demand for bushmeat has increased.

Where a road might be 'catastrophic'
The study, published in the journal Ecological Monographs, comes amid heated debate over the Tanzanian government's plans to build a paved 53-kilometer (33-mile) highway across the Serengeti National Park. Last month, the East African Court of Justice (EACJ) ruled against the so-called Serengeti Highway, which aims to carry up to 800 commercial vehicles a day across what is now the migratory path for millions of wildebeests, zebras, gazelles and other animals.

The ruling that construction of a bitumen or tarmac road across the park is unlawful sparked celebrations as well as new worries. Environmental groups like the Africa Network for Animal Welfare, which brought the original case, said the ruling leaves open the possibility of another type of road construction along the same route.

Hopcraft said the migration study underscores how "catastrophic" a road would be to the Serengeti's animals, forcing them to cross the road to access the Mara River, their only source of water in the dry season.

"These animals respond to the way humans behave. If we are going to put up infrastructure, animals will respond," he said. "A road could well be the straw that breaks the camel's back on this ecosystem."

According to the study, which delivered real-time location data via text message to scientists, wildebeests and zebras migrate together but move for different reasons. Wildebeests are driven by the highest-quality food and, Hopcraft said, are even willing to risk the threat of lions or other predators to get it. Zebras, by contrast, will follow the food but are more likely to veer off-course to avoid predators.

People, though, are where they share common cause. When humans are detected, wildebeests will race straight ahead, while zebras will do a 180-degree turn and keep running—both bypassing food to get to safety.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500

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