News / Africa

Satellites Help Explain Zebra Migration

Multimedia

Audio
Joe DeCapua
Every year, zebras in Botswana begin a 580-kilometer migration looking for food. Even though it’s an annual event, researchers only had a general idea when it would start and they didn’t know which route the animals would take or why. That is, until now.


Sometime in September, zebras begin their trek from Botswana’s Okavango Delta to the Makgadikgadi Salt Pans. Pieter Beck, a research associate at the Woods Hole Research Center, was among those studying the migration.

“Like most large herbivores that naturally migrate, zebra migrations have been under threat. Across the globe, most of the big migrations already are under threat. So, conserving the ones that exist is of course important; and finding ways where people and wildlife can live together is critical if you want to achieve that,” he said.

One big mystery was how do zebras choose the route to the salt pans? It was not because the knowledge had been passed down from one generation to the next. Researchers knew that between 1968 and 2004 veterinary fences were built across potential migration routes. The fences were put up to help prevent wild buffalo from transmitting disease to cattle.

Within three years of the fences being taken down, the zebras began to migrate. Now, keep in mind that the fences were up for 36 years and that zebras usually live no more than 12 years in the wild.

“The fences were up longer than the lifespan of the zebra. So the zebra that we tracked making this hundreds of miles of migration – they couldn’t have learned it from their parents. So they actually rediscovered it using probably exploratory walks. It’s a very fascinating story in that sense and sort of a good news story in conservation. And these are unfortunately rare these days,” said Beck.

So, researchers turned to the U.S. space agency NASA and took a close look at some of its satellite images and data.

“The NASA instruments that we worked with orbit the Earth and they give us a global picture of rainfall and of vegetation productivity. So those are the two metrics we extracted. The rainfall data you can get for the tropics in particular. And we can see every six hours from satellites an estimate of how much it rained. For the vegetation data we can see globally every day, if there are no clouds, how productive the vegetation is. Is it green or is it wilted or is it dry?”

What Beck and his colleagues found was that when enough rain has fallen there’s a “surge in the greening of grasses.”

Beck said, “We do see that rainfall is what gets them going. That was very clear. But then, once they’re on the move, they appear to rely both on rainfall and the productivity of vegetation because the leg of migration we looked at is at the end of the dry season. So when we look at the vegetation that’s surrounding them and how green it is, really, we can tease out how fast the animals will migrate.”

And they’ll follow the greening vegetation. But Beck said the zebras are in tune with the environment and don’t simply move blindly in one direction.

“If the rains then abate or you get an interruption, then they’ll actually reverse their migration, which is something that had only very rarely been documented. They’ll reverse their migration and wait for the next spell of rains. Same thing when they return from the very productive grasslands where they are in the wet season. If you get a very late rain spell, they’ll actually reverse again and extend the period that they can graze in the grasslands,” he said.

So researchers wanted to know whether being in tune with their environment would help the zebras – and possibly other migrating animals -- adapt to climate change.

Beck said, “In our research we assessed the chance of those weather systems becoming decoupled and really the cues that animals rely on now not becoming reliable anymore in the future – and whether the animals’ behavior is adaptable enough to cope with that.”

That kind of knowledge could help in the conservation of wild animals. He also says knowing which migration routes animals will take may help game park rangers and others better protect them from poachers. Beck and his colleagues presented their findings in the Journal of Geophysical Research – Biogeosciences.

You May Like

Turkey's Erdogan: Women Not Equal to Men

Speaking at conference in Istanbul, President Erdogan says Islam has defined a position for women: motherhood More

Ahead of SAARC Summit, Subdued Expectations

Some regional analysts say distrust between Pakistani, Indian officials has slowed SAARC's progress over the year More

Philippines Leery of Development on Reef Reclamation in S. China Sea

Chinese land reclamation projects in area have been ongoing for years, but new satellite imagery reportedly shows China’s massive construction project More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Aung San Suu Kyi: Myanmar Opposition to Keep Pushing for Constitutional Changei
X
November 24, 2014 10:09 PM
Myanmar opposition leader Aung San Suu Kyi says she and her supporters will continue pushing to amend a constitutional clause that bars her from running for president next year. VOA's Than Lwin Htun reports from the capital Naypyitaw in this report narrated by Colin Lovett.
Video

Video Aung San Suu Kyi: Myanmar Opposition to Keep Pushing for Constitutional Change

Myanmar opposition leader Aung San Suu Kyi says she and her supporters will continue pushing to amend a constitutional clause that bars her from running for president next year. VOA's Than Lwin Htun reports from the capital Naypyitaw in this report narrated by Colin Lovett.
Video

Video Mali Attempts to Shut Down Ebola Transmission Chain

Senegal and Nigeria were able to stop small Ebola outbreaks by closely monitoring those who had contact with the sick person and quickly isolating anyone with symptoms. Mali is now scrambling to do the same. VOA’s Anne Look reports from Mali on what the country is doing to shut down the chain of transmission.
Video

Video Ukraine Marks Anniversary of Deadly 1930s Famine

During a commemoration for millions who died of starvation in Ukraine in the early 1930s, President Petro Poroshenko lashed out at Soviet-era totalitarianism for causing the deaths and accused today’s Russian-backed rebels in the east of using similar tactics. VOA’s Daniel Shearf reports from Kyiv.
Video

Video Hong Kong Protests at a Crossroads

New public opinion polls in Hong Kong indicate declining support for pro-democracy demonstrations after weeks of street protests. VOA’s Bill Ide in Guangzhou and Pros Laput in Hong Kong spoke with protesters and observers about whether demonstrators have been too aggressive in pushing for change.
Video

Video US Immigration Relief Imminent for Mixed-Status Families

Tens of thousands of undocumented immigrants in the Washington, D.C., area may benefit from a controversial presidential order announced this week. It's not a path to citizenship, as some activists hoped. But it will allow more immigrants who arrived as children or who have citizen children, to avoid deportation and work legally. VOA's Victoria Macchi talks with one young man who benefited from an earlier presidential order, and whose parents may now benefit after years of living in fear.
Video

Video New Skateboard Defies Gravity

A futuristic dream only a couple of decades ago, the hoverboard – a skateboard that floats above the ground - has finally been made possible. While still not ready for mass production, it promises to become a cool mode of transport... at least over some surfaces. VOA’s George Putic reports.
Video

Video Falling Gas Prices Impact US Oil Extraction

With the price of oil now less than $80 a barrel, motorists throughout the United States are benefiting from gas prices below $3 a gallon. But as VOA’s Kane Farabaugh reports, the decreasing price of petroleum has a downside for the hydraulic fracturing industry in the United States.
Video

Video Tensions Build on Korean Peninsula Amid Military Drills

It has been another tense week on the Korean peninsula as Pyongyang threatened to again test nuclear weapons while the U.S. and South Korean forces held joint military exercises in a show of force. VOA’s Brian Padden reports from the Kunsan Air Base in South Korea.
Video

Video Mama Sarah Obama Honored at UN Women’s Entrepreneurship Day

President Barack Obama's step-grandmother is in the United States to raise money to build a $12 million school and hospital center in Kogelo, Kenya, the birthplace of the president's father, Barack Obama, Sr. She was honored for her decades of work to aid poor Kenyans at a Women's Entrepreneurship Day at the United Nations.
Video

Video Ebola Economic Toll Stirs W. Africa Food Security Concerns

The World Bank said Wednesday that it expects the economic impact of the Ebola outbreak on the sub-Saharan economy to cost somewhere betweenf $3 billion to $4 billion - well below a previously-outlined worst-case scenario of $32 billion. Some economists, however, paint a gloomier picture - warning that the disruption to regional markets and trading is considerable. Henry Ridgwell reports from London.
Video

Video Chaos, Abuse Defy Solution in Libya

The political and security crisis in Libya is deepening, with competing governments and, according to Amnesty International, widespread human rights violations committed with impunity. VOA’s Al Pessin reports from London.
Video

Video US Hosts Record 866,000 Foreign Students

Close to 900,000 international students are studying at American universities and colleges, more than ever before. About half of them come from Asia, mostly China. The United States hosts more foreign students than any other country in the world, and its foreign student population is steadily growing. Zlatica Hoke reports.

All About America

AppleAndroid