Picture a truly wild horse. You might be imagining a graceful mare rearing on her legs on the shores of Assateague Island, her golden mane silhouetted against the sunset. What you should be picturing is the shorter, stockier Przewalski's horse, the endangered subspecies that once roamed the steppe of China and Mongolia. No offense to other horses, but these brown beauties are the only equines who can claim authentic wildness.
All other so-called “wild” horses all share one thing in common: They were once domesticated by man, a process that fundamentally changed their biology. By contrast, the Przewalski's horse—also known as the Asian wild horse or takhi in Mongolian—has never been domesticated. Researchers have learned that this horse is not an ancestor of domestic horses, but a distant cousin that diverged around 500,000 years ago. Even its genetics reflect this evolutionary divergence: The Przewalski's has two more chromosomes than domestic horses.
Yet while they never endured the hand of man, the Przewalski's horse still suffered mightily from his presence. Once these zebra-sized creatures galloped across Europe, Central Asia and China; researchers even believe they are depicted in ancient cave paintings in France. But in the 1960s overhunting, habitat loss and competition with livestock forced the Przewalski’s into extinction in the wild. Only after years of being raised in captive populations in zoos were the horses reintroduced into parts of Mongolia, where today a small population of around 500 live permanently or semi-permanently.
That these rare wild horses still exist in a state of wildness at all is itself a conservation success. But their relatively newfound freedom also creates a new challenge for researchers: finding and monitoring the horses across vast swaths of land, which is key to helping them thrive in the long term in the face of myriad threats. For conservationists, the question is: How do you track the wildest horses in the world?
That question became especially urgent in 2001, after the horses were released in Xinjiang, China at the Kalamaili Nature Reserve. During the first harsh winter season, several of those reintroduced horses died. This sudden setback prompted the Xinjiang Forestry Department and the Cologne Zoo in Germany to look to a new conservation tool: GPS satellite tracking. They approached the Smithsonian Institution, where researchers have long used the technology for projects related to rare wild animal populations like Asian elephants, golden-headed lion tamarins and the scimitar-horned oryx in Chad.
(Smithsonian, by the way, also breeds captive Przewalski’s horses, though it has not introduced any back into the wild. The National Zoo has produced 37 Przewalski’s horse offspring since it began in 1983, according to Budhan Pukazhenthi, a reproductive physiologist at Smithsonian’s Conservation Biology Institute who works with these horses. Currently there are seven male and 12 female horses, three of which are pregnant, at the SCBI’s center at Front Royal.)
Melissa Songer, a conservation biologist at the SCBI, was one of the researchers who participated in the initial GPS tracking effort in China. In 2006, she and colleagues placed GPS transmitter collars on wild horses, which captured the animals’ hourly GPS coordinates and their corresponding dates and times. The data was uploaded to satellites, and transmitted every few days to the team via email. Because Przewalksi’s horses roam in herds of about five or six, Songer could use just four of the GPS collars to determine the locations of over 20 horses.
In addition to helping staff locate the horses, the ongoing project aims to answer questions about the size of the horses’ range of travel, their habitat preferences, the environment of the places to which they travel and the social dynamics of the groups. “For a conservation biologist, this is the holy grail because it’s an opportunity to get back into the wild what’s been lost,” says Songer.
In April 2016, Songer and her colleague Peter Leimgruber helped launch the first satellite tracking project among herds of reintroduced Przewalski’s horses in Hustai Nuruu National Park in northern Mongolia in partnership with the Minnesota Zoo. Currently, the reintroduced horses only use 35 percent of the space reserved for them. The scientists hope to use the data they’ve gathered—including data from infrared cameras around watering holes—to develop strategies to encourage the animals to use more of the area and resources.
For the horses to survive, it is also crucial that the local human population also be engaged in the conservation effort, says Songer. After all, human activity was a significant factor in the extinction of the population in the mid-twentieth century. In herding their livestock, humans created competition for land and resources, endangering the Przewalski’s horses.
To further the project on the ground in China when she is not present, Songer has trained local Kazakh livestock herders to track the horses with handheld devices. Songer says that once she explained the project and the significance of the horses, the herders were eager to be involved. “They love horses, they’re horse people,” she says. “They rely on horses for their transportation. So we already had a strong basis for trying to involve them. You want them to feel involved in the process, not just feel threatened by it.”
While Songer spends more time on the ground collaring horses and training people to monitor the animals, Leimgruber, who has a background in landscape conservation ecology, spends more time looking at the data through statistical analysis and spatial modeling. The two approaches complement each other: “You can’t just put them somewhere and think they’re going to survive,” says Leimgruber. “We study landscapes with satellite imagery integrated with survey data on the ground … We find the best places for these animals to live, and then we start the reintroduction efforts.”
Although the species has jumped from extinct to endangered status in the wild, the conservation work is far from done. Some herds are still only released in the milder months—and for a horse as wild as the Przewalski’s, this dependency on human intervention is far from optimal. In the future, scientists want to use the GPS data to identify the most suitable habitats possible. Moreover, since the reintroduced populations stem from a small group of founder animals, they hope to increase genetic exchange within the species to set them up for long-term survival.
As Pukazhenti of SCBI puts it: “It’s almost a lifetime commitment to make sure the species survives.”