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Article: The Wild Horse Returns to Mongolia

A species that was near extinction is now recovering in the wild because of active management by conservation biologists.

In 1880, Russian explorer Nikolai Przewalski encountered a small population of wild horses while traversing central Asia. The horses were compact, with heavy limbs and strong necks. They had dun coats with a white stain around the nose and a thin, dark stripe that ran from the mane to the tail. These were unlike the so-called “wild” horses that abound in Australia and North America, which are actually feral, meaning they descended from domesticated horses. These Asian horses were a distinct species of Equus that had never been domesticated. Scientifically described for the first time, the species was given the name Equus przewalskii, Przewalski's horse.

captivity

Takhi in early captivity.


European breeders and zoo directors rushed to collect specimens of the "newly discovered" wild horse, which was actually well known to people in Mongolia and other parts of central Asia. A few dozen foals reached zoos and privately owned parks in Europe and North America, but many perished during the trans-Siberian journey.

Meanwhile the wild populations of Przewalski's horse, or takhi (meaning “spirit”), as they are known in Mongolia, declined as animals were killed and collected by Europeans, displaced by domesticated grazing animals, and hunted for food. Over time, their numbers and habitat shrank until the takhi became extinct in the wild in the late 1960s.

A Wild Horse in Captivity

Conservation biologists have dreamed of reintroducing this species since the last wild takhi disappeared in the 1960s. But the challenges of such an endeavor were daunting. The takhi would be the first species or subspecies to return to portions of its native habitat after so long in captivity—between 10 and 14 generations—with no new genetic input. “Breeding animals in captivity almost always results in the offspring being adapted to life in captivity in some way or another,” points out Michael Stüwe, a research associate with the Smithsonian Institution.

By 1947, just 31 takhi survived in captivity, only 12 of which actually bred. That year a wild mare was caught in Mongolia, bringing the breeding population up to 13 individuals, from which all takhi alive today are descended. Populations as small and isolated as this have a serious risk of inbreeding. Restricted diversity, known as a genetic bottleneck, can lower the vigor of takhi descendants. This can result in shorter life spans, increased mortality among foals, and weakened hind legs.

To reduce further inbreeding and improve the horses' health, Jiri Volf, a zoologist at the Prague Zoo, began a detailed international studbook for the species in 1960. Volf and team chronicled the lineage of every takhi in captivity—59 worldwide at the time—and encouraged institutions not to breed closely related horses.

Since 1960, the horses have been bred with remarkable success. There are now five regional breeding programs for captive Przewalski's horses in North America, Europe, Russia, and Australia. To manage the population of takhi for optimum genetic health, breeders use strategies to reduce inbreeding and ensure that rare genes do not disappear. The number of captive takhi around the world has now reached almost 2,000 individuals, and computerized records detail their genealogical relationships.

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Wild horses are reintroduced to Mongolia as local people look on.

AMNH


Preparing for Reintroduction

With an eye toward establishing a reservoir of healthy, semi-wild horses for future release into the wild, herds have been established on “semi-reserves" of 5 hectares (12 acres) or more in the Netherlands and Germany. There, zoo-raised horses selected for genetic variation form social bonds and learn to find their own food. The herds have thrived and have produced many foals.

By the early 1980’s, the successful breeding of takhi led to international efforts to identify potential sites suitable for a reintroduction of the captive horses into the wild. The sites needed to fulfill the takhi’s habitat requirements, providing year-round availability of permanent water, food, and shelter. Domestic livestock and particularly domestic horses could not be present, but the presence of indigenous grazers and predators indicated a healthy ecosystem. Since then, several reintroduction projects have been established: two in Mongolia, two in China, and one in the Ukraine.

The Takhi Go Home

One of the reintroduction efforts is bringing the takhi back to the site where the last one was spotted in the wild in the late 1960’s. In 1990, the Mongolian government and the German-funded Christian Oswald Foundation established a takhi reintroduction station, called Takhin Tal—Mongolian for “Valley of the Wild Horses”—on the northern border of the Gobi B Nature Reserve in a region called the Dzungarian Gobi. The site is about 1,045 kilometers (650 miles) southwest of Mongolia’s capital, Ulaanbaatar.

The Gobi B Nature Reserve is 12,000 square kilometers (about 4,600 square miles) of semidesert, a rocky plain bordered by mountains and interrupted by brush and rocky outcrops. Underground streams called "gobs" (which give the Gobi its name) feed springs that provide a periodic source of water, enough to sustain considerable biodiversity. Some springs function year-round, supporting narrow bands of pasture. Fields of saxaul, a woody shrub, provide food in the winter. During the summer the herds stay near a water source, “but the moment the first snow comes here, they're completely independent of this water source,” says Dr. Chris Walzer, a veterinarian from Austria's Salzburg Zoo who is working with the Takhin Tal program. The reintroduced horses’ “home range” varies with the seasons and with the snowfall.

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The fence posts beyond this group of takhi signal the enclosure area in which reintroduced horses are initially contained for an adjustment period.

AMNH


A Rough Start

During the early 1990’s, the Takhin Tal program faced serious challenges. Conditions in central Asia are extreme: temperatures can reach 40 degrees Celsius (104 degrees Fahrenheit) in the summer and -45 degrees Celsius (-49 degrees Fahrenheit) in the winter. The periodic sleet storms that coat the landscape in ice can lead to starvation among grazing livestock. Some Mongolian biologists believe that severe winters in the mid-20th century contributed to the extinction of the takhi.

The harsh conditions took a toll on the reintroduced takhi. The horses, which were released to a fenced area for an initial acclimatization period, competed for the scarce food and water. A number of takhi died. The horses, especially those more than three years old, were slow to adjust to the difficult climate and poor vegetation. In addition, a tick-borne disease affected the mares’ reproductive rates, foals were lost to wolves, and several young horses drowned when a dam across a nearby stream broke.

Since then, the Takhin Tal conservationists have adopted a process of selecting only the healthiest horses for reintroduction. There have also been improvements in health care and shipping methods. Newly reintroduced Takhi held in the fenced enclosures receive supplementary hay and pellets between October and April and may receive additional water during extreme droughts.

These remedies have promoted rates of reproduction and survival for animals born in the reserve. “So we've got over a lot of the initial problems, we've learned a lot more about the horses, and we're quite optimistic,” says Walzer. The extreme winter of 1999–2000 killed millions of Mongolian livestock, but all the takhi survived.

Michael Stüwe observes that the takhi released on the plain outside the enclosures did better than the ones inside the enclosures, despite the latter’s supplementary feed. “They know how to find shelter and food, even at temperatures of 40 degrees below zero, blizzards blowing for days without end. They look good in the spring, with shiny coats.” Nor has scarcity of water proved to be a major problem for those outside the enclosures. The year-round springs are between 25 and 45 kilometers (16 to 28 miles) apart, and the takhi can easily cover that distance in the course of their movements.

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Scientists are tracking the whereabouts of some of the reintroduced takhi with radio collars.

AMNH


A Growing Population

Since 1997, takhi have been successfully breeding in the wild, though captive animals have deliberately been introduced to supplement the wild herds at Takhin Tal. As of winter 2007, 115 takhi were roaming free in the Dzungarian Gobi, including 76 animals born in the wild. These numbers are especially significant since computer models suggest that a group of 100 free-ranging horses is considered a viable population—one that is biologically resilient and less prone to natural catastrophes that could wipe out large numbers of takhi.

But that doesn’t mean that the takhi are now on solid enough footing to live wild without intervention. Scientists monitor the movements of the horses every day, either by direct observation or by radio telemetry (several horses in each family group wear radio collars). “It's a long-term commitment,” says Waltzer. “We're going to be here for many years to come.”

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