A population of zebras undertakes the longest terrestrial migration in Africa, according to researchers who just identified the zebras' 311-mile journey.
The discovery, published in the latest issue of the journal Oryx, provides compelling evidence that conservation efforts often require multinational coordinated support.
In this case, "The migration involves up to several thousand zebra making a return journey from the Chobe River floodplains in Namibia/Botswana to Nxai Pan National Park in Botswana," lead author Robin Naidoo told Discovery News.
"This is a 500-km (311-mile) round trip journey along an almost direct north-south axis," continued Naidoo, who is a senior conservation scientist at World Wildlife Fund.
The zebras spend the dry season along the Chobe River floodplains, and then when the rains begin, migrate over several weeks to the Nxai Pan National Park, where they spend several months before returning to the Chobe River floodplains.
Zebras move with direction and purpose along the migration route.
"The zebras are moving at a relatively fast pace, though certainly not running for most of the journey," Naidoo said.
Zebras will, however, run, to get through challenging terrain, such as this watering hole, or while trying to escape predators.
The primary food of zebras is grass, which they wash down with plenty of water.
The migration likely happens annually, in response to seasonal changes, but Naidoo and his team have not yet confirmed how frequently the zebras follow the lengthy migration route.
Mothers guard their vulnerable foals during the migration. The migration can be especially arduous for such youngsters. It's possible that they, and the other zebras, are genetically predisposed to make the journey.
As for why the migration started in the first place, Naidoo explained, "Nxai Pan National Park is known as an area with fertile soils, and so the grazing there would be very nutritious and appealing to zebra whose dry season grazing areas would have become depleted after months of use."
"However," he added, "there are other, closer areas to the Chobe River that also have productive soils, and therefore the reason why zebra skip these areas and move the longer distance to Nxai Pan may involve genetic coding or cultural/learned behavior."
Zebras are closely related to horses and, like horses, are very social animals. Entire zebra families make the long round-trip trek through Namibia and Botswana.
Social structure depends on the particular species, but most live in "harems" consisting of one stallion with up to six mares and their foals. When under attack, groups will huddle together with the foals in the middle while the stallion attempts to confuse or otherwise chase away the hunter.
Zebras sleep while standing up, and will only do so when other zebras are around to hopefully warn them of predators.
Nxai Pan National Park is one of Africa's great treasures, featuring large tracts of largely unspoiled land and wildlife. It is being considered for inclusion in what is known as the Kavango-Zambezi Transfrontier Conservation Area (KAZA).Robin Naidoo/WWF
Nxai Pan National Park is one of Africa's great treasures, featuring large tracts of largely unspoiled land and wildlife. It is being considered for inclusion in what is known as the Kavango-Zambezi Transfrontier Conservation Area (KAZA).
"The zebra migration occurs entirely within the boundaries of KAZA, making the effective on-the-ground management of KAZA a key factor in allowing it to continue to persist," Naidoo said.
Parts of the zebra migration route are also used by other animals, such as giraffes. Both giraffes and zebras are plant-eating animals, so they tend to leave each other alone.
Giraffes are not on the list of longest migrators in Africa, though.
"In addition to the world-famous Serengeti wildebeest migration, lengthy migrations in Africa have been documented for wildebeest, eland, and hartebeest in Botswana's Kalahari region, wildebeest and zebra in eastern Angola/western Zambia, and kob and topi (both African antelopes) in Sudan," Naidoo said.
He added, "The longest documented migrations anywhere in the world are for caribou in North America and Russia, and for Tibetan antelope and Mongolian gazelles in Asia."
Schuyler Shepherd, Wikimedia Commons
Lions are the primary predators of zebras during the migration, according to Naidoo. Lions such as this female will lie in wait, but then can run up to 50 miles per hour in short, speedy bursts to chase down dinner.
Zebras are frequently seen traveling in a line during the migration.
Naidoo and his team mention that the zebras face many human-related threats during their long journey. Immediate concerns, he said, include policies surrounding hunting and fencing in the areas where the zebras reside and migrate. Climate change looms as another likely threat.
"Certainly, changes in hydrological regimes or the amount and/or timing of precipitation could change when, where, and how zebra migrate in the wet season," he explained. "If the climate were to become drier to the point where drinking water at Nxai Pan was no longer sufficient to support populations of migrant animals such as zebra, then the migration would likely cease."
Hopefully this young zebra, which appears to be sticking its tongue out at the camera, made it safely through the recent migration.
"The newly discovered zebra migration puts in perspective how much we still don't know about the natural world," Naidoo said. "For a large conspicuous species such as the zebra to be performing a migration of such length without anyone knowing about it is astonishing in this day and age."