Originally published on Nov. 13, 1995
After decades of intense effort by wildlife biologists and zookeepers from more than 25 countries, the world's oldest and only truly wild horses are once again grazing freely on the steppes of central Asia.
The small, stocky Przewalski's horse (Equus przewalskii), believed to be the distant ancestor of all domestic horses, was once so close to extinction it was virtually written off by zoologists as a viable species. Today, with three wild herds in Mongolia and a captive population of about 1,200 animals worldwide, its future is more promising than at any time in the last 50 years.
Reintroducing Przewalski's horses to the wild has been the dream of conservation-biologists ever since the last horses were seen in Mongolia 's Gobi desert in 1968, but most believed the chances of such a project succeeding were minimal.
"Reintroducing captive-bred animals to so unforgiving a habitat was considered logistically and biologically difficult," says Jan Vegter, project manager for the Dutch-based Foundation Reserves for the Przewalski's horse, a private organization, which, with financial support for Mongolia from the Dutch government, is helping the Mongolian Association for the Conservation of Nature and Environment to manage the reintroduction project. "Combine the challenge of breeding these horses with the complexities of international politics," adds Vegter, "and you have a project with a far greater chance for failure than for success."
But in 1992, after years of careful preparation, 16 captive-bred Przewalski's horses were flown to Mongolia from Holland and Ukraine, where zoologists have been breeding the horses for 50 years. At the Ulan Bator airport, a team of Mongolian scientists, their Dutch counterparts, and a small crowd of enthusiastic well-wishers were waiting to escort the wooden-crated animals to the recently established 150,000-acre Hustain Nuruu Steppe Reserve 100 miles southwest of the capital. There the horses were kept under close observation in two 75-acre semi-wild enclosures for two years. This time was needed, according to Jan Vegter, to ensure the horses' safety and help ease their transition from their European breeding reserves to the harsh living conditions of Mongolia 's steppes - where winter temperatures can drop to 70 below zero, and packs of wolves would share the rugged terrain. Initially skeptical Mongolian officials were won over to the reintroduction project when the Foundation Reserves for the Przewalski Horse agreed to support the local economy by hiring displaced herdsmen as wardens and rangers. "They provide daily reports on the movements of the horses and help to patrol the reserve," says Vegter.
On June 24, 1994, as the ranking Buddhist Lama for Mongolia chanted a blessing from the highest mountain in the reserve, and a crowd of cheering neighbors looked on, the fence gates were opened and 15 khaki-colored horses galloped into the wild (a mare had died during the initial trip from Holland; the survivors were two stallions and their harems). With far less fanfare, a third group of seven horses was introduced to another part of the reserve this summer.
"All three herds are doing extremely well," reports John de Meij, the 29- year-old assistant manager of the project, who, with his wife, Jacomijn, lives in one of the reserve's 13 "gers" (portable tent-like houses made from felt and canvas) for four months each year. "They have adapted remarkably well to the climate, to the wild food available, and to the complex social patterns that characterize the species."
So well have they adjusted, in fact, that the 31 wild horses now in the Hustain Nuruu Steppe Reserve include 12 offspring born on the site in the last three years. The foals, some of which are now entering their first Mongolian winter, are the first of their species to be born in the wild in almost a quarter-century.
This success and more technical aspects of the reintroduction project were among the topics discussed at an international conference on Przewalski's horse held in Ulan Bator in early August.
To many conservation biologists, the horse's reintroduction to Mongolia represents an encouraging model for wild animal reintroductions worldwide. To Mongolians, it has symbolic importance that far outweighs the technical triumphs of successful breeding, transportation and refuge management. In a country where more than half of the 2.5 million population uses domestic horses for transportation and where horses are seen as universal symbols of freedom and domestic tranquillity, the return of a wild-horse species that roamed in the days of Genghis Khan is a source of considerable national pride.
Unlike the wild horses that live in parts of North America and Europe, which are really feral domestic horses, the Przewalski's horse as a species has never been domesticated. Far more aggressive than its domestic counterpart, the recently released horses, known as "Takhi" in Mongolia, demonstrate a complex variety of social behaviors that have survived generations of captive breeding.
A Przewalski's horse differs from a domestic horse (Equus caballus) on a genetic level: even though the two species are able to inter-breed, blood analysis shows the Przewalski's horse to have 66 chromosomes while all domestic horses have 64.
The average Przewalski's horse stands about 50 inches (12 hands plus two inches) at the shoulder, almost a foot shorter than a domestic thoroughbred, and weighs 550 to 600 pounds, several hundred pounds less than its domesticated cousin.
As a species, Przewalski's horse is a survivor, but barely. Once abundant throughout Asia and Europe (where early humans frequently painted its distinctive shape on the walls of caves), the horse began its decline in numbers and reduction in range at the end of the last Ice Age, about 10,000 years ago. At that time, warming climatic conditions changed the horse's favored steppe-like grasslands to forests in much of Europe and Russia, and so reduced the areas where it could most effectively feed and reproduce. Human pressure from hunting and widespread grazing of livestock further reduced the horses' range, until, by the 18th and 19th centuries, only a small area of steppe at the edge of the Gobi desert in northern China and southern Mongolia provided the marginal conditions required for the horses' survival.
So isolated were the wild areas supporting the remaining herds that Western scientists did not know that the species existed until the Russian explorer Col. Nikolai Przewalski (1839-88) was given the skull and skin of a specimen by a group of local hunters during an expedition in Mongolia in 1878. Przewalski presented the specimens to the Zoological Museum of the Academy of Science in St. Petersburg. The species was named in his honor just three years later.
As zoos rushed to collect examples of the rare horse and local herdsmen continued to shoot the animals for food, its numbers dwindled, until the wild population could no longer sustain itself. By the late 1960s, Przewalski's horse was extinct in the wild.
Despite the deaths of many horses at the hands of inept collectors, enough animals were captured from the wild to establish a number of captive breeding populations in European, Russian and American zoos. Even these came perilously close to extinction. The devastation of World War II reduced the world's zoo population of Przewalski's horses to just three stallions and seven mares by 1945. It is from this stock, and one wild mare, that all of the present population descends - including those recently reintroduced to the wild.
"The health of any species depends in large measure on the variability of its gene pool," observes Ronald Keiper of Pennsylvania State University, who has studied the behavior of captive herds of Przewalski's horses in Holland and Germany for more than a decade. "With so small a pool to start with, careful breeding was essential for success."
The Przewalski's horse was saved from potentially disastrous inbreeding, according to Keiper, by the efforts of Jiri Volf of the Zoological Garden in Prague who began a detailed stud book for the species in 1960. By chronicling the lineage of every individual, breeders were able to reduce the inbreeding that could cause congenital defects in the animals. When the Prague Zoo published the first of Volf's annual genealogical reports, there were 59 Przewalski's horses in captivity worldwide and their situation was declared "catastrophic" by the zoologists involved with the species' long term preservation. Today, with more than 1,200 animals in existence and computerized records detailing their relationships, the species' survival is far more secure.
While European zoos have been at the center of the Przewalski's horse breeding efforts, a number of American zoos have played a role in saving the species, including the Philadelphia Zoo, which had a breeding stock from 1913 until the last one died in 1956. The Bronx Zoo, the Catskill Game Farm near Kingston, N.Y., and the San Diego Zoo still have breeding herds that can be seen by the public. The National Zoo's Conservation and Research Center in Front Royal, Va., has a herd but it is not open for public view.
Meanwhile in Mongolia, the reintroduction of horses to the wild continues with success. "Our long-term goal is to have a free, self-sustaining population of 300 to 400 Przewalski's horses living in the Hustain Nuruu Steppe Reserve," says Jan Vegter. "We plan to release three more groups of five to eight horses each over the next 10 years. " Parallel programs in the Dzungarian desert in China and Mongolia 's Gobi National Park hold promise for an even broader distribution of the Przewalski's horse in the decades to come.
Robert McCracken Peck, a fellow of the Academy of Natural Sciences of Philadelphia, accompanied an academy research expedition to Mongolia through a grant from the National Science Foundation.