Longest Migration Among African Mammals Discovered
Baku, May 29 (AZERTAC). A population of zebras surprised biologists by making a more than 300-mile beeline across parts of Namibia and Botswana—the longest big-mammal migration ever documented in Africa.
In the wilds of Africa, food and water come and go with the seasons, and animals follow. The Serengeti is the site of what most considers the most dramatic migration, with giant herds of millions of animals—some 750,000 zebras and 1.2 million wildebeests as well as gazelles and eland—traveling from the Ngorongoro area in southern Tanzania to the Masai Mara in lower Kenya and returning as the rains dictate.
But when it comes to the longest hike endpoint to endpoint, Africa has a new record holder. As reported in an article published online today in the journal Oryx, the migration, which has now been observed in consecutive years, isn't on the scale of what goes down on the Serengeti—it involves just a few thousand Burchell's zebras (Equus quagga). But the animals cover more than 300 miles (500 kilometers) in a straight-line, up-and-back journey across Namibia and Botswana. (In the Serengeti the animals meander more before circling back, so their feet touch more ground, but the distance between the zebras' two destinations is greater.)
"The almost unerring north-south direction was unusual," says lead author Robin Naidoo, senior conservation scientist at the World Wildlife Fund (WWF). But there was an even bigger surprise. "The distance covered by these zebra was a total shock to all of us involved in the study, as well as to people familiar with wildlife conservation in the region," he says. "Nobody knew that something of this scale, with this much ground covered, was occurring. "
Naidoo says the research team in Namibia—scientists from WWF and Namibia's Ministry of Environment and Tourism—had a suspicion that the zebras were up to something, "since animals seemed to just show up on the floodplains in Salambala communal conservancy in the dry season, where there are permanent water sources, and then disappear in the wet season."
That the animals were migrating with the rains wasn't in itself surprising. "But we didn't have any inkling they were moving such a long distance away from Namibia," Naidoo says. As it happened, the same animals his team was observing in Namibia were being satellite collared by biologists from Elephants Without Borders across the Chobe River in Botswana. When the teams joined forces, they realized the impressive extent of the animals' travels.
Another bit of intrigue: "Our preliminary investigations suggest that there were similar, alternative wet-season destinations that were closer to zebras' dry-season haunts—yet they were bypassed," says Naidoo. Why wouldn't the animals choose a more efficient trip?
Research with other migratory mammals has shown that generations of animals may stick to the same route corridors, down to the nearest meter. For example, says ungulate ecologist Mark Hebblewhite of the University of Montana, "we have evidence that pronghorn antelope in the western U.S. have migrated over the same routes for more than 6,000 years. This is probably a product of both the landscape and cultural transmission of knowledge amongst social animals."
Naidoo says there may also be a genetic basis for such traditions. But it will take more years of monitoring the zebras to figure out what drives them, he says, "to determine whether the same endpoints and same trajectory are in fact used every year."
Other news in this section
