Returning Wild Horses to the Wild : Program Hopes to Resettle Przewalskis

For 2,000 years, Chinese literature referred to wild horses roaming the steppes and deserts of western Asia.

But by the late 19th Century, when scientists finally confirmed the existence of the Mongolian wild horse--the only wild horse species in the world--its survival in the wild was already precarious. And in the past quarter-century, the animal, also known as the Przewalski horse after the Russian who discovered proof of it, has become extinct in its natural habitat.

The species is being kept alive, however, through the efforts of about 70 zoos and wildlife parks in North America and Europe. And plans are under way to reintroduce the horses to the wild in the next decade.

Herds are to be formed from the hundreds of Przewalskis successfully bred in captivity, some from the largest North American collection at the San Diego Zoo and Wild Animal Park and others from the world’s most extensive preserve in the Soviet Union’s Ukraine.

Key elements of the project, being planned under the auspices of the United Nations, include preparing protected areas in Mongolia and other Asian high-plains regions, developing the expertise to manage--but not control--the horses once they are released, and minimizing international politics during the complicated restoration process.

Scientists also have had to develop a new breeding program to increase the horses’ chances of survival in the wild.

If the program meets its goal, either by its tentative 1991 date or later, it will represent another notch in the efforts of zoologists to place endangered or extinct-in-the-wild animals into as natural a state as possible.

The Arabian oryx was reintroduced into Oman and Jordan in the 1970s after being made extinct in desert areas by machine gun-toting game hunters. Scientists have talked of placing the lemur, a small nocturnal primate, back on the island of Madagascar. And controversy is afoot over suggestions that the five California condors still in the wild be captured and held in the Los Angeles and San Diego zoos until sufficient numbers can be bred and put back into their Southern California refuge.

In the case of the Mongolian wild horses, “the effort started as a labor of love and scientific interest among many zoologists in the 1960s,” said geneticist Oliver A. Ryder of the research department at the San Diego Zoological Society. Ryder spoke at a United Nations-sponsored conference in Moscow on the Przewalski last year, where the 1991 target date was set.

“The 1991 date is optimistic,” Ryder said, explaining that it assumes “remaining conflicts will be resolved and that government-to-government problems can be minimized.”

The Chinese, who want to reintroduce the horse in wilderness areas of their country, did not participate in the Moscow meeting. Their program, which will receive a stallion from San Diego in September for breeding purposes, might proceed apart from U.N. plans, according to Jim Dolan, general curator for mammals at the zoological society.

Other problems include the lack of expertise in Mongolia, which has no zoos and no experience in handling endangered animals, Dolan said.

“The releases should be done,” Dolan said. “The Mongolians want to do it, the Chinese want to do it, and if it can be done in the areas where the horses formerly existed, the results are obviously beneficial.”

Little Is Known

For a species that may go back more than 10,000 years--cave drawings in Europe feature a horse strikingly similar to the Przewalski--relatively little is known about how the horse lived in the wild.

In 1881, Russian nobleman and explorer N. M. Przewalski sponsored the first expedition to obtain a carcass of the only species of never-domesticated horses. Even after the skeleton was displayed in St. Petersburg (now Leningrad), most scientists remained unconvinced that the animal was truly a horse, pointing out its stocky, mule-like appearance.

Proof of its wild status was not solid until the Duke of Bedford captured Przewalskis and bred them at his Woburn Abbey game preserve in England around the turn of the century. Even in captivity, they would not be tamed.

The population of the tan, white-snouted horses shrank in their natural habitats--Mongolia, the eastern Soviet Union and western China--under competition from large numbers of domestic animals for limited water sources. The horses also were hunted by nomads who considered them pests good only for their skin and meat.

A Przewalski was last taken from captivity in 1947 and no sightings--even unconfirmed--have been made since the early 1960s.

700 in Captivity

But there are at least 700 of the horses in captivity, with the numbers growing by perhaps as many as 100 a year. The official studbook for births worldwide is kept by zookeepers in Prague, Czechoslovakia. The lineage of all the horses can be traced back to 12 animals, 11 captured at the turn of the century and the 1947 catch, a mare named Orlitza.

For many years, these animals were mated without efforts to vary the gene pool, with many mares and their offspring being bred with only one stallion. At a certain point, inbreeding can become so serious that the animals would be unlikely to survive if returned to the wild, because genetic traits favoring domestication would be highly dominant, Ryder said.

After a 1964 symposium on Przewalskis in East Germany, an effort was made to expand blood lines by using more stallions in breeding, Ryder said.

“That was a major problem, the erosion of the gene pool using too few stallions,” he said. “Now we want every stallion to breed, and breed in several different locations.”

Ryder coordinates a 7-year-old cooperative breeding program among nine North American zoos. In one exchange, a stallion brought to the Bronx Zoo from the Moscow Zoo was transferred in 1983 to the Wild Animal Park, where he impregnated seven mares before suffering a fatal back injury last year.

“Breeding programs have had astounding successes everywhere,” Ryder said. “And our own herd in San Diego is magnificent.” It now includes 11 males and 18 females.

Ryder said he is frustrated when guides at the Wild Animal Park spend less time describing the Przewalski horses than pointing out the one domesticated camel that shares their large enclosure.

‘Made a Major Commitment’

“San Diego has made a major commitment,” Ryder said. “We’ve got two major breeding groups, one on-exhibit and one off-exhibit, and a group of bachelor males off-exhibit. Those males can be sent around the world as they near breeding age. We’re also working with research on semen collection, on artificial insemination, so that perhaps we could freeze away representative semen in case a catastrophic epidemic ever occurred.”

One of the prerequisites for the release program will be placement of an initial herd in an area closely resembling the wild, but where the horses can still be controlled and watched for behavioral or genetic problems. One unanswered question is whether stallions more than occasionally kill their young, something that happened once last year at the Wild Animal Park.

“You have to remember that we don’t understand their biology all that well, and that real studies of their behavior . . . only have begun in the last 10 years at spacious zoo environments,” Ryder said.

Dolan said the Askania Nova wildlife preserve in the Ukraine most closely approximates the Mongolian habitat and will be the best staging area.

He said the horses will not be completely free of human intervention even after the releases begin, citing the management necessary throughout Africa to preserve elephants and other large mammals in national game parks.

“If the animals can be put into a secure area, with sufficient water and feed, I see no problems scientifically,” Dolan said.