The best way to help cows and zebras? Make them live together

LOUISVILLE, KENTUCKY—No rancher likes to think of their cows sharing space with a lion, or even an impala. But that may be the best way to save Africa’s big game, according to a study reported here this week at the annual meeting of the Ecological Society of America. The counterintuitive approach could help the livestock—and therefore ranchers—as well.

“There’s potential for it to be a win-win situation,” says Steven Seagle, an ecologist at Appalachian State University in Boone, North Carolina, who was not involved with the work.

Historically, ranchers have fenced their livestock in to keep wildlife out, fearing their animals would catch diseases, be eaten, or be outcompeted for food. And conservationists have focused on setting aside natural preserves for the wild species they are trying to protect. But as farming spreads throughout Africa, it has crowded wildlife out of almost all its natural habitats.

In Kenya, a few landowners have been experimenting with keeping a mix of wildlife and cattle on their land. Lions, zebras, and other charismatic creatures draw paying tourists, and cattle can be protected at night from predators by crowding them in temporary metal corrals. But it was unclear how the wildlife’s presence affected the cattle and vice versa.

So ecologist Brian Allan at the University of Illinois in Urbana and ecologist Felicia Keesing at Bard College in Annandale, New York, investigated 23 ranches on the Laikipia Plateau in central Kenya. The area, once full of giraffes, zebras, and rhinos, is now divided into cattle ranches sometimes reaching 40,000 hectares—about 75,000 U.S. football fields—in size.

Most of the ranches contained at least some of the wildlife once common in the area, and one-third had about equal numbers of wildlife and cattle. The greater the proportion of livestock to wild animals on a ranch, the fewer blood-sucking ticks found on every animal at the ranch, including wildlife, the researchers discovered.

That’s because ranchers often spray their livestock with chemicals to kill ticks, which can weaken their hosts and spread disease. (When the scientists collected more than 1000 of the pests from the ranches, ground them up, and extracted all the DNA they contained, they discovered that about one in six ticks was infected by a least one animal pathogen, and many carried more.) Just spraying the livestock was enough to reduce the tick population on both types of animals. The more livestock in proportion to wildlife, the more effective the tick removal. Where there were a lot of livestock, ticks disappeared, the team reports. “It’s an astounding drop,” Seagle says.

“We can use domesticated animals … as a means of reducing disease” in wild animals, says Meggan Craft, a wildlife disease ecologist at the University of Minnesota in Saint Paul.

The wildlife also provides some benefit to the livestock. Even though zebras and wild antelopes eat the same foods as livestock, the researchers found that the integrated ranches had more grass than ranches with just livestock. That could be because ranches can’t support large numbers of both livestock and wildlife; as a result, livestock is often reduced when wildlife comes in, and they are less likely to deplete grass through overgrazing.

Ranchers who kept both types of animals also didn’t lose money. They were just as well off as those that had just livestock or just wildlife, likely because of the combination of tourist and ranching income.

Given the current conflict between wildlife and human activities over space, this dual-use approach seems promising, Craft says. “It gives us a little bit of optimism about the future of wildlife.”

*Correction, 14 August, 2:25 p.m.: An earlier version of this story miscalculated the approximate conversion of hectares to football fields.