Zoo Plays Role : Przewalski Horses Soon to Return to Wild

For 2,000 years, Chinese literature has referred to a wild horse roaming the vast 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 horse species that has never been domesticated--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 the animal, has become extinct in its natural habitat, being kept alive only through the efforts of about 70 zoos and wildlife parks in North America and Europe.

Plans are under way, however, to reintroduce Przewalski horses to the wild in the next decade by forming herds from the hundreds of horses successfully bred in captivity, including the largest North American collection at the San Diego Zoo and Wild Animal Park and the most extensive preserve worldwide in the Soviet Union.

Under the auspices of the United Nations, scientists have developed the genetic skills to minimize the risk to survival should reintroduction occur. The key elements for the project include preparing suitably-protected areas in Mongolia and other Asian high-plain regions, developing the expertise to manage--but not control--the horses once they are released, and attempting to minimize international politics during the complicated restoration process.

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

The Arabian oryx was successfully reintroduced into Oman and Jordan in the 1970s after being hunted to extinction in the desert vastness by machine gun-toting game hunters out for pleasure. Scientists hope to place the lemur, a small nocturnal primate, back on the island of Madagascar. And there is controversy over suggestions that the few remaining 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.

Efforts to return the Przewalski horses to the wild “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 last year on the Przewalski restoration where the 1991 timetable was drawn up.

“The 1991 date is optimistic,” Ryder said. “It is a feasible projection (technically) but depends on optimism that remaining conflicts will be resolved and that government-to-government problems can be minimized.”

One of the major problems involves the lack of expertise in Mongolia on monitoring a release program, because that country has no zoos and no experience in handling endangered animals, said Jim Dolan, general curator for mammals at the zoological society.

Dolan recently returned from a trip to the East Berlin Zoo, a world-famous zoological park whose officials told him the 1991 goal was doubtful.

“There may be, in addition, some problems at a government-to-government level between the Soviets and Mongolia,” Dolan said, though he said zoo officials are not privy to the nature of those problems. The Chinese also want to reintroduce the horse into Western China and will receive a stallion from San Diego in September for breeding purposes, Dolan said. But the Chinese did not participate in the Moscow meeting and their program might proceed apart from U.N. plans.

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

For a species that may go back more than 10,000 years--cave drawings in Europe feature a horse strikingly similar to Przewalski’s--relatively little is known about how the horse lived in the wild. More than 100 years ago, in 1881, Russian nobleman and explorer N.M. Przewalski uncovered the secret of the world’s only non-domesticated horse. Przewalski sponsored the first expedition to obtain a carcass of the animal.

Even after the skeleton was displayed in St. Petersburg (now Leningrad) in 1881, 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.

Zoos and wildlife parks have had remarkable success breeding the tan, white-snouted horses that have become extinct in the wild since the first scientific studies of them 80 years ago. Their natural habitats in Mongolia, the eastern Soviet Union and western China had shrunk due to competition--mainly from large numbers of domestic animals--for limited water sources, and from being hunted by nomads who considered the horses pests suitable only for their skin and meat. The last horse was taken into captivity in 1947 and no sightings--even unconfirmed--have been made since the early 1960s.

Today, there are at least 700 Przewalskis in captivity, with the number growing by perhaps as many as 100 a year. The official studbook for all births worldwide is kept by zoo keepers in Prague, Czechoslovakia. All the horses trace their lineage back to 12 animals captured in the wild, 11 at the turn of the century and the 12th, the mare named Orlitza taken in 1947.

For many years, the animals were bred without regard to varying the gene pool, which resulted in extensive inbreeding from mating of closely-related individuals. At a certain point, inbreeding can become so serious that the animals would be unlikely to survive if returned to the wild, because certain genetic traits favoring domestication would be highly dominant.

Beginning in 1964 with the first symposium on Przewalskis in East Germany, a new approach was begun, attempting to expand blood lines by breeding more and more stallions. Ryder said that for many years, many mares were bred by just one stallion, a situation that has changed during the past 20 years or so.

“That was a major problem, the erosion of the gene pool using too few stallions,” Ryder said. “Now we want every stallion to breed, and breed in several different locations.” Ryder serves as the coordinator for the North American cooperative breeding program, a seven-year old program among nine North American zoos which involves trading horses among themselves to better conserve the gene pool. For example, a stallion previously 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.” In fact, Ryder admits to some frustration when guides at the Wild Animal Park spend less time describing Przewalski’s horses--the latest figures show the herd with 11 males and 18 females--than pointing out the domesticated camel that shares the large enclosure.

“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.”

Said mammals curator Dolan: “There’s no question now of availability of animals for a release program. And the Russians have a lot of experience in managing groups in captivity in large areas,” referring to the Askania Nova agricultural and wildlife preserve in the Ukraine.

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 that could be harmful if not corrected before their final release.

Some sociobiological studies have been done at the Wild Animal Park to observe how the herds act in large, open spaces. An unanswered question for now is whether stallions more than occasionally kill their young, as happened last year at the Wild Animal Park when a stallion killed the offspring of another stallion. Dolan said that the Soviet preserve most closely approximates the Mongolian habitat and will be the best staging area.

Added Ryder: “You have to remember that we don’t understand their biology all that well, and that real studies of their behavior could never be done in the wild (because they were near extinction) and only have begun in the last 10 years at spacious zoo environments.”

Dolan stressed that the horses will not be completely free of human intervention even after the releases begin, citing the example of the oryx in the Middle East.

“We will be managing them in the wild, and what you are talking about is the degree of management,” he said, citing the management necessary throughout Africa today to preserve elephants and other large mammals in national game parks.

Because of the management techniques needed, Dolan believes the 1991 target established at the Moscow conference is too optimistic. The Mongolians have little or no experience in managing animals and must gain that expertise, probably from the Soviets, before the reintroduction of Przewalskis can occur, Dolan said.

Dolan speculated that the Chinese might be able to begin a release program in their isolated western provinces about the same time as Mongolia is ready. The Chinese are establishing a herd with the help of the San Diego Zoological Society. San Diego officials will transfer a stallion to the Beijing Zoo in September, Dolan said.

“The animals probably existed in China into the mid-1950s but from 1939 to the Cultural Revolution end (late 1970s), nothing was studied in China,” Dolan said.

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