Przewalski's horse (''Equus ferus przewalskii'' or ''Equus przewalskii''),
also called the takhi,
Mongolian wild horse or Dzungarian horse, is a rare and endangered
wild horse
The wild horse (''Equus ferus'') is a species of the genus Equus (genus), ''Equus'', which includes as subspecies the modern domestication of the horse, domesticated horse (''Equus ferus caballus'') as well as the Endangered species, endangered ...
originally native to the
steppe
In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes.
Steppe biomes may include:
* the montane grasslands and shrublands biome
* the tropical and subtropica ...
s of
Central Asia
Central Asia is a region of Asia consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The countries as a group are also colloquially referred to as the "-stans" as all have names ending with the Persian language, Pers ...
. It is named after the Russian geographer and explorer
Nikolay Przhevalsky. Once
extinct in the wild, since the 1990s it has been
reintroduced to its native habitat in Mongolia in the
Khustain Nuruu National Park, Takhin Tal Nature Reserve, and Khomiin Tal, as well as several other locales in Central Asia and
Eastern Europe
Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
.
[
Several genetic characteristics of Przewalski's horse differ from what is seen in modern domestic horses, indicating neither is an ancestor of the other. For example, Przewalski's horse has 33 chromosome pairs, compared to 32 for the domestic horse. Their ancestral lineages split from a common ancestor between 160,000 and 38,000 years ago, long before the ]domestication of the horse
It is not entirely clear how, when or where the domestication of the horse took place. Although horses appeared in Paleolithic cave art as early as 30,000 BCE, these were wild horses and were probably hunted for meat. The clearest evidence o ...
. Przewalski's horse was long considered the only remaining truly wild horse, in contrast with the American mustang and the Australian brumby, which are instead feral horses descended from domesticated
Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a steady supply of reso ...
animals. That status was called into question when domestic horses of the 5,000-year-old Botai culture of Central Asia were found to be more closely related to Przewalski's horses than to ''E. f. caballus''. The study raised the possibility that modern Przewalski's horses could be the feral descendants of the domestic Botai horses. However, it remains possible that both the Botai horses and the modern Przewalski's horses descend separately from the same ancient wild Przewalski's horse population. Its taxonomic position is still debated, with some taxonomists treating Przewalski's horse as a species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
, ''E. przewalskii'', others as a subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
of wild horse
The wild horse (''Equus ferus'') is a species of the genus Equus (genus), ''Equus'', which includes as subspecies the modern domestication of the horse, domesticated horse (''Equus ferus caballus'') as well as the Endangered species, endangered ...
(''E. ferus przewalskii'') or a variety of the domesticated horse (''E. caballus'').
Przewalski's horse is stockily built, smaller, and shorter than its domesticated relatives. Typical height is about , and the average weight is around . They have a dun coat with '' pangaré'' features and often have dark primitive markings
Primitive markings are a group of equine coat color, hair coat markings and qualities seen in several equine species, including horses, donkey, donkeys, and asses. In horses, they are associated with primitive breeds, though not limited to such ...
.
Taxonomy
Przewalski's horse was formally described as a novel species in 1881 by Ivan Semyonovich Polyakov. The taxonomic position of Przewalski's horse remains controversial, and no consensus exists about whether it is a full species (as ''Equus przewalskii''); a subspecies of ''Equus ferus'' the wild horse
The wild horse (''Equus ferus'') is a species of the genus Equus (genus), ''Equus'', which includes as subspecies the modern domestication of the horse, domesticated horse (''Equus ferus caballus'') as well as the Endangered species, endangered ...
(as ''Equus ferus przewalskii'' in trinomial nomenclature
In biology, trinomial nomenclature is the system of names for taxa below the rank of species. These names have three parts. The usage is different in zoology and botany.
In zoology
In zoological nomenclature, a trinomen (), trinominal name, or ...
, along with two other subspecies, the domestic horse ''E. f. caballus'', and the extinct tarpan
The tarpan (''Equus ferus ferus'') was a free-ranging horse population of the Eurasian steppe from the 18th to the 20th century. What qualifies as a tarpan is subject to debate; it is unclear whether tarpans were genuine wild horses, feral domest ...
''E. f. ferus''); or even a subpopulation of the domestic horse.[ The American Society of Mammalogists considers Przewalski's horse and the tarpan both to be subspecies of ''Equus ferus'', and classifies the domestic horse as a separate species, ''Equus caballus''.
]
Lineage
Genetic analysis shows that the takhi and the domestic horse differ significantly, with neither ancestral to the other. The evolutionary divergence
In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the rate that the vector field alters the volume in an infinitesimal neighborhood of each point. (In 2D this "volume" refers to ...
of the two populations was estimated to have occurred about 72,000–38,000 years ago, well before domestication, most likely due to climate, topography, or other environmental changes.
According to a 2009 study, the earliest known domestic horses were found at settlements of the Botai culture, from about 5500 years ago. These horses were raised for meat and milk. In 2018, a new study indicated ancient horses of the Botai culture are related to takhis, not to domestic horses as was previously thought. Specifically, the Botai horses appeared to be ancestral to the modern takhi, because all seven takhis nested within the phylogenetic tree
A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...
of the 20 Botai horses. No comparison was made to definitively wild early takhis. The authors posit that modern Przewalski's horses are feral
A feral (; ) animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in som ...
descendants of the ancient Botai domesticated animals, rather than representing a surviving population of never-domesticated horses. Another geneticist pointed out that Przewalski's horses may have simply descended from the same wild population that the Botai horses came from, which would still be compatible with the findings of the study.
In 2021, William Taylor and Christina Barron-Ortiz disputed the evidence for domestication of Przewalski's horse. Their case was rejected by Alan Outram and colleagues in a paper which was not dated or peer-reviewed. Taylor reiterated his arguments that Przewalski's horse had never been domesticated in an article in ''Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it, with more than 150 Nobel Pri ...
'' in 2024.
In any case, the Botai horses were found to have negligible genetic contribution to any of the ancient or modern domestic horses studied, indicating that the domestication of the latter was independent, involving a different wild population, from any possible domestication of Przewalski's horse by the Botai culture.
Characteristics
Przewalski's horse is stockily built in comparison to domesticated horses, with shorter legs, and is much smaller and shorter than its domesticated relatives. Typical height is about , and length is about . It weighs around . The coat is generally dun in color with '' pangaré'' features, varying from dark brown around the mane, to pale brown on the flanks, and yellowish-white on the belly, as well as around the muzzle. The legs of Przewalski's horse are often faintly striped, also typical of primitive markings
Primitive markings are a group of equine coat color, hair coat markings and qualities seen in several equine species, including horses, donkey, donkeys, and asses. In horses, they are associated with primitive breeds, though not limited to such ...
. The mane stands erect and does not extend as far forward, while the tail is about long, with a longer dock and shorter hair than seen in domesticated horses. The hooves of Przewalski's horse are longer in the front and have significantly thicker sole horns than feral horses, an adaptation that improves hoof performance on terrain.
Genomics
The karyotype
A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...
of Przewalski's horse differs from that of the domestic horse, having 33 chromosome pairs versus 32, apparently due to a fission of a large chromosome ancestral to domestic horse chromosome 5 to produce Przewalski's horse chromosomes 23 and 24, though conversely, a Robertsonian translocation that fused two chromosomes ancestral to those seen in Przewalski's horse to produce the single large domestic horse chromosome has also been proposed.
Many smaller inversions, insertions and other rearrangements were observed between the chromosomes of domestic and Przewalski's horses, while there was much lower heterozygosity
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.
Mos ...
in Przewalski's horses, with extensive segments devoid of genetic diversity, a consequence of the recent severe bottleneck
Bottleneck may refer to:
* the narrowed portion (neck) of a bottle
Science and technology
* Bottleneck (engineering), where the performance of an entire system is limited by a single component
* Bottleneck (network), in a communication network
* ...
of the captive Przewalski's horse population.[ In comparison, the chromosomal differences between domestic horses and ]zebra
Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: Grévy's zebra (''Equus grevyi''), the plains zebra (''E. quagga''), and the mountain zebra (''E. ...
s include numerous large-scale translocations, fusions, inversions, and centromere
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fiber ...
repositioning.[ Przewalski's horse has the highest ]diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...
chromosome number among all equine species. They can interbreed with the domestic horse and produce fertile offspring, with 65 chromosomes.
The mitochondrial genome has 37 genes that are 99.63% identical to that of the domestic horse.
Ecology and behavior
Przewalski reported the horses forming troops of between five and fifteen members, consisting of a mature stallion, his mares and foals. Modern reintroduced populations similarly form family groups of one adult stallion, one to three mares, and their common offspring that stay in the family group until they are no longer dependent, usually at two or three years old. Young females join other harems, while bachelor stallions as well as old stallions who have lost their harems join bachelor groups. Family groups can join to form a herd that moves together.
The patterns of their daily lives exhibit horse behavior similar to that of feral horse herds. Stallions herd, drive, and defend all members of their family, while the mares often display leadership in the family. Stallions and mares stay with their preferred partners for years. While behavioral synchronization is high among mares, stallions other than the main harem stallion are generally less stable in this respect.
Home range in the wild is little studied, but estimated as in the Hustai National Park and in the Great Gobi B Strictly Protected Area. The ranges of harems are separated, but slightly overlapping. They have few modern predators, but one of the few is the Himalayan wolf.
Horses maintain visual contact with their family and herd at all times, and have a host of ways to communicate with one another, including vocalizations, scent marking, and a wide range of visual and tactile signals. Each kick, groom, tilt of the ear, or other contact with another horse is a means of communicating. This constant communication leads to complex social behaviors among Przewalski's horses.
The historical population was said to have lived in the "wildest parts of the desert" with a preference for "especially saline districts". They were observed mostly during spring and summer at natural wells, migrating to them by crossing valleys rather than by way of higher mountains.
Diet
Przewalski horse's diet consists of vegetation. Many plant species are in a typical Przewalski's horse environment, including: '' Elymus repens'', ''Carex
''Carex'' is a vast genus of over 2,000 species of grass-like plants in the family (biology), family Cyperaceae, commonly known as sedges (or seg, in older books). Other members of the family Cyperaceae are also called sedges, however those of ge ...
''spp., Fabaceae
Fabaceae () or Leguminosae,[International Code of Nomen ...](_blank)
, and Asteraceae
Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...
.
Looking at the species' diet overall, Przewalski's horses most often eat ''E. repens'', ''Trifolium pratense
''Trifolium pratense'' (from Latin prātum, meaning meadow), red clover, is a herbaceous species of flowering plant in the bean family, Fabaceae. It is native to the Old World, but planted and naturalised in many other regions.
Description
...
'', '' Vicia cracca'', '' Poa trivialis'', ''Dactylis glomerata
''Dactylis glomerata'' is a species of flowering plant in the grass family Poaceae, known as cock's-foot,Interactive Flora of NW Europ''Dactylis glomerata'' (Cock's-foot)/ref> also colloquially as orchard grass, or cat grass (due to its populari ...
'', and '' Bromus inermis''.
While the horses eat a variety of different plant species, they tend to favor different species at different times of year. In the springtime, they favor ''Elymus repens'', '' Corynephorus canescens'', '' Festuca valesiaca,'' and '' Chenopodium album''. In early summer, they favor ''Dactylis glomerata'' and '' Trifolium'', and in late summer, they gravitate towards ''E. repens'' and ''Vicia cracca''.
In winter the horses eat ''Salix
Willows, also called sallows and osiers, of the genus ''Salix'', comprise around 350 species (plus numerous hybrids) of typically deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions.
Most species are known ...
''spp., ''Pyrus communis
''Pyrus communis'', the common pear, is a species of pear native plant, native to central and eastern Europe, and western Asia.
It is one of the most important fruits of temperate regions, being the species from which most orchard pear cultivars ...
'', ''Malus
''Malus'' ( or ) is a genus of about 32–57 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples (sometimes known in North America as crabapples) and wild apples.
The genus i ...
sylvatica'', ''Pinus sylvestris
''Pinus sylvestris'', the Scots pine (UK), Scotch pine (US), Baltic pine, or European red pine is a species of tree in the pine family Pinaceae that is native plant, native to Eurasia. It can readily be identified by its combination of fairly s ...
'', '' Rosa'' spp., and '' Alnus'' spp. Additionally, Przewalski's horses may dig for ''Festuca
''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on ...
'' spp., ''Bromus inermis'', and ''E. repens'' that grow beneath the ice and snow. Their winter diet is very similar to the winter diet of domestic horses, but differs from that revealed by isotope analysis of the historical (pre-captivity) population, which switched in winter to browsing shrubs, though the difference may be due to the extreme habitat pressure the historical population was under.[ In the wintertime, they eat their food more slowly than they do during other times of the year. Przewalski's horses seasonally display a set of changes collectively characteristic of physiologic adaptation to starvation, with their ]basal metabolic rate
Basal metabolic rate (BMR) is the rate of energy expenditure per unit time by endothermic animals at rest.. In other words it is the energy required by body organs to perform normal It is reported in energy units per unit time ranging from watt ( ...
in winter being half what it is during springtime. This is not a direct consequence of decreased nutrient intake, but rather a programmed response to predictable seasonal dietary fluctuation.
Reproduction
Mating occurs in late spring or early summer. Mating stallions do not start looking for mating partners until the age of five. Stallions assemble groups of mares or challenge the leader of another group for dominance. Females are able to give birth at the age of three and have a gestation period of 11–12 months. Foals are able to stand about an hour after birth. The rate of infant mortality among foals is 25%, with 83.3% of these deaths resulting from leading stallion infanticide
Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose being the prevention of re ...
.[ Foals begin grazing within a few weeks but are not weaned for 8–13 months after birth.][ They reach sexual maturity at two years of age.
]
Population
History
Przewalski's-type wild horses appear in European cave art dating as far back as 20,000 years ago,[ but genetic investigation of a 35,870-year-old specimen from one such cave instead showed an affinity with extinct Iberian horse lineage and the modern domestic horse, suggesting that it was not Przewalski's horse being depicted in this art. Horse skeletons dating to the fifth to the third millennia BCE, found in Central Asia, with a range extending to the southern Urals and the Altai, belong to the genetic lineage of Przewalski's horse. Of particular note are the horses of this lineage found in the archaeological sites of the ]Chalcolithic
The Chalcolithic ( ) (also called the Copper Age and Eneolithic) was an archaeological period characterized by the increasing use of smelted copper. It followed the Neolithic and preceded the Bronze Age. It occurred at different periods in di ...
Botai culture. Sites dating from the mid-fourth-millennium BCE show evidence of horse domestication. Analysis of ancient DNA from Botai horse specimens from about 3000 BCE reveals them to have DNA markers consistent with the lineage of modern Przewalski's horses.
There are sporadic reports of Przewalski's horse in the historical record before its formal characterization. The Buddhist monk Bodowa wrote a description of what is thought to have been Przewalski's horse about AD 900, and an account from 1226 reports an incident involving wild horses during Genghis Khan
Genghis Khan (born Temüjin; August 1227), also known as Chinggis Khan, was the founder and first khan (title), khan of the Mongol Empire. After spending most of his life uniting the Mongols, Mongol tribes, he launched Mongol invasions and ...
's campaign against the Tangut empire.[ In the fifteenth century, Johann Schiltberger recorded one of the first European sightings of the horses in the journal recounting his trip to Mongolia as a prisoner of the Mongol Khan. Another was recorded as a gift to the Manchurian emperor around 1630, its value as a gift suggesting a difficulty in obtaining them.][ John Bell, a Scottish doctor in service to ]Peter the Great
Peter I (, ;
– ), better known as Peter the Great, was the Sovereign, Tsar and Grand Prince of all Russia, Tsar of all Russia from 1682 and the first Emperor of Russia, Emperor of all Russia from 1721 until his death in 1725. He reigned j ...
from 1719 to 1722, observed a horse in Russia's Tomsk Oblast that was apparently this species, and a few decades later in 1750, a large hunt with thousands of beaters organized by the Manchurian emperor killed between two and three hundred of these horses.[
]
The species is named after a Russian colonel of Polish descent, Nikolai Przhevalsky (1839–1888) (Nikołaj Przewalski in Polish). An explorer and naturalist, he obtained the skull and hide of an animal shot in 1878 in the Gobi near today's China–Mongolia border. He would travel to the Dzungarian Basin to observe it in the wild. In 1881, the horse received a formal scientific description and was named ''Equus przevalskii'' by Ivan Semyonovich Polyakov, based on Przewalski's collection and description, while in 1884, the sole exemplar of the horse in Europe was a preserved specimen in the Museum of the Russian Academy of Sciences in St. Petersburg. This was supplemented in 1894 when the brothers Grum-Grzhimailo returned several hides and skulls to St. Petersburg and described the horse's behavior in the wild.[ A number of these horses were captured around 1900 by Carl Hagenbeck and placed in zoos, and these, along with one later captive, reproduced to give rise to today's population.
After 1903, there were no reports of the wild population until 1947, when several isolated groups were observed and a lone ]filly
A filly is a female horse that is too young to be called a mare. There are two specific definitions in use:
*In most cases, a ''filly'' is a female horse under four years old.
*In some nations, such as the United Kingdom and the United States
...
captured. Although local herdsmen reported seeing as many as 50 to 100 takhis grazing in small groups then, there were only sporadic sightings of single groups of two or three animals after that, mostly near natural wells.[ Two scientific expeditions in 1955 and 1962 failed to find any. After herders and naturalists reported single harem groups in 1966 and 1967, the last observation of the wild horse in its native habitat was of a single stallion in 1969.] Expeditions after this failed to locate any horses, and the species would be designated "extinct in the wild" for over 30 years.[ Competition with livestock, hunting, capture of foals for zoological collections, military activities, and harsh winters recorded in 1945, 1948, and 1956 are considered to be main causes of the decline in Przewalski's horse population.]
The wild population was already rare at its first scientific characterization. Przewalski reported seeing them only from a distance and may have instead sighted herds of local onager Mongolian wild asses. He was only able to obtain specimens of the type from Kirghiz hunters. The range of Przewalski's horse was limited to the arid Dzungarian Basin in the Gobi Desert.["Przevalsky's Wild Horse", ''Nature'', 30:391-392 (1884).] It has been suggested that this was not their natural habitat, but, like the onager, they were a steppe animal driven to this barren last refuge by the dual pressures of hunting and habitat loss to agricultural grazing. There were two distinct populations recognized by local Mongolians, a lighter steppe variety and a darker mountain one. This distinction is seen in early twentieth-century descriptions. Their mountainous habitat included the ''Takhiin Shar Nuruu'' (The Yellow Wild-Horse Mountain Range). In their last decades in the wild, the remnant population was limited to the small region between the Takhiin Shar Nuruu and Bajtag-Bogdo mountain ridges.
Captivity
Attempts to obtain specimens for exhibit and captive breeding
Captive breeding, also known as captive propagation, is the process of keeping plants or animals in controlled environments, such as wildlife reserves, zoos, Botanical garden, botanic gardens, and other Conservation biology, conservation facilitie ...
were largely unsuccessful until 1902, when 28 captured foals were brought to Europe. These and a small number of additional captives would be distributed among zoos and breeding centers in Europe and the United States. Many facilities failed in their attempts at captive breeding, but a few programs were established. However, by the mid-1930s, inbreeding had caused reduced fertility, and the captive population experienced a genetic bottleneck, with the surviving captive breeding stock descended from only 11 of the founder captives.[ In addition, in at least one instance, the progeny of interbreeding with a domestic horse was bred back into the captive Przewalski's horse population. However, recent studies have shown only minimal genetic contribution of this domestic horse to the captive population.]
The situation was improved when the exchange of breeding animals among facilities increased genetic diversity and there was a consequent improvement in fertility, but the population experienced another genetic bottleneck when many of the horses failed to survive World War II. The most valuable group, in Askania Nova
Askania-Nova () is a biosphere reserve located in Kherson Oblast, Ukraine, within the dry Taurida steppe near Oleshky Sands. An active member of the UNESCO Man and the Biosphere Programme, the reserve maintains and conserves native steppe habi ...
, Ukraine
Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
, was shot by German soldiers during World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
occupation, and the group in the United States had died out. Only two captive populations in zoos remained, in Munich
Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...
and in Prague
Prague ( ; ) is the capital and List of cities and towns in the Czech Republic, largest city of the Czech Republic and the historical capital of Bohemia. Prague, located on the Vltava River, has a population of about 1.4 million, while its P ...
, and of the 31 remaining horses at war's end, only 9 became ancestors of the subsequent captive population.[ By the end of the 1950s, only 12 individual horses were left in the world's zoos.]
A wild-caught mare captured as a foal a decade earlier was introduced into the Ukrainian captive population in 1957. This would prove the last wild-caught horse, and with the presumed extinction of the wild population, last sighted in Mongolia in the late 1960s, the captive population became the sole representatives of Przewalski's horse.[ Genetic diversity received a much-needed boost from this new source, with the spread of her bloodline through the inbred captive groups leading to their increased reproductive success, and by 1965, there were more than 130 animals spread among thirty-two zoos and parks.
]
Conservation efforts
In 1977, the Foundation for the Preservation and Protection of the Przewalski Horse was founded in Rotterdam
Rotterdam ( , ; ; ) is the second-largest List of cities in the Netherlands by province, city in the Netherlands after the national capital of Amsterdam. It is in the Provinces of the Netherlands, province of South Holland, part of the North S ...
, the Netherlands, by Jan and Inge Bouman. The foundation started a program of exchange between captive populations in zoos worldwide to reduce inbreeding
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely genetic distance, related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genet ...
and later began its own breeding program. As a result of such efforts, the extant herd has retained a far greater genetic diversity than its genetic bottleneck made likely. By 1979, when this concerted program of population management to maximize genetic diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
was begun, there were almost four hundred horses in sixteen facilities,[ a number that had grown by the early 1990s to over 1,500.][
While dozens of zoos worldwide have Przewalski's horses in small numbers, specialized reserves are also dedicated primarily to the species. The world's largest captive-breeding program for Przewalski's horses is at the ]Askania Nova
Askania-Nova () is a biosphere reserve located in Kherson Oblast, Ukraine, within the dry Taurida steppe near Oleshky Sands. An active member of the UNESCO Man and the Biosphere Programme, the reserve maintains and conserves native steppe habi ...
preserve in Ukraine. From 1998, thirty-one horses were also released in the unenclosed Chernobyl Exclusion Zone
The Chernobyl Nuclear Power Plant Zone of Alienation, also called the 30-Kilometre Zone or simply The Zone, was established shortly after the 1986 Chernobyl disaster in the Ukrainian SSR of the Soviet Union.
Initially, Soviet authorities declar ...
in Ukraine
Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
and Belarus
Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...
. People evacuated the zone after the Chernobyl accident, so now it serves as a deserted '' de facto'' nature reserve.[ Though poaching has taken a toll on numbers, as of 2019 the estimated population in the Chernobyl zone was over 100 individuals.]
Le Villaret, located in the Cevennes National Park in southern France and run by the Association Takh, is a breeding site for Przewalski's horses that was created to allow the free expression of natural Przewalski's horse behaviors. In 1993, eleven zoo-born horses were brought to Le Villaret. Horses born there are adapted to life in the wild, free to choose their mates, and required to forage independently. This was intended to produce individuals capable of being reintroduced into Mongolia. In 2012, 39 individuals were at Le Villaret.[ An intensely researched population of free-ranging animals was also introduced to the ]Hortobágy National Park
Hortobágy () is an 800 km2 national park in eastern Hungary, rich with folklore and cultural history. The park, a part of the Alföld (Great Plain), was designated as a national park in 1973 (the first in Hungary), and elected among the W ...
'' puszta'' in Hungary; data on social structure, behavior, and diseases gathered from these animals are used to improve the Mongolian conservation effort. An additional breeding population of Przewalski's horses roams the former Döberitzer Heide military proving ground
A proving ground is an installation or reservation in which technology such as weapons, military tactics and automobile prototypes are experimented with or tested. Proving grounds can be operated by government bodies or civilian industries. The ...
, now a nature reserve in Dallgow-Döberitz, Germany. Established in 2008, this population comprised 24 horses in 2019. Another population is being established in the Iberian System in Spain, the first free-roaming Przewalski’s horses in Western Europe.
In 2024, a Colorado
Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
rancher discovered what appears to be a Przewalski's horse at a Kansas
Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
livestock auction, mistakenly identified as a mule. Another similar horse was found at a Utah
Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
sanctuary. Genetic tests suggest both are Przewalski's horses, raising concerns about how they ended up in U.S. auctions. One horse, Fiona, was euthanized following apparent organ failure, while the other's fate is unreported.
Reintroduction
The Przewalski's Horse Reintroduction Project of China was initiated in 1985 when 11 wild horses were imported from overseas. After more than two decades of effort, the Xinjiang
Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People' ...
Wild Horse Breeding Centre has bred a large number of horses, 55 of which were released into the Kalamely Mountain area. The animals quickly adapted to their new environment. In 1988, six foals were born and survived, and by 2001, over 100 horses were at the centre. , the center hosted 127 horses divided into 13 breeding herds and three bachelor herds.
Reintroductions organized by Western European countries started in the 1990s. Several populations have now been released into the wild. A cooperative venture between the Zoological Society of London
The Zoological Society of London (ZSL) is a charity and organization devoted to the worldwide animal conservation, conservation of animals and their habitat conservation, habitats. It was founded in 1826. Since 1828, it has maintained London Zo ...
and Mongolian scientists has successfully reintroduced these horses from zoos into their natural habitat in Mongolia. In 1992, 16 horses were released into the wild in Mongolia, followed by additional animals later. One of the areas to which they were reintroduced became Khustain Nuruu National Park in 1998. Another reintroduction site is Great Gobi B Strictly Protected Area, located at the fringes of the Gobi Desert.
In 2001, Przewalski's horses were reintroduced into the Kalamaili Nature Reserve in Xinjiang
Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People' ...
, China.
Since 2004, there has been a program to reintroduce Przewalski's horses that were bred in France into Mongolia. Instrumental to that 2004 reintroduction was Claudia Feh, a Swiss equine specialist and conservation biologist, Feh led an effort to bring together animals that zoos had conserved to create a breeding population in southern France. Then, after it was established, three family groups were relocated to Khovd in western Mongolia. At a site on the northern edge of the Gobi Desert, Feh worked in cooperation with local people to ensure the horses survived and flourished. For this work, Feh received a Rolex Award in 2004.
In 2004 and 2005, 22 horses were released by the Association Takh to a third reintroduction site in the buffer zone of the Khar Us Nuur National Park, in the northern edge of the Gobi ecoregion. In the winter of 2009–2010, one of the worst '' dzud'' or snowy winter conditions ever hit Mongolia. The population of Przewalski's horse in the Great Gobi B SPA was drastically affected, providing clear evidence of the risks associated with reintroducing small and sequestered species in unpredictable and unfamiliar environments.
After reintroduced horses had successfully reproduced, the status of the animal was changed from "extinct in the wild" to "endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
" in 2005,[ while on the ]IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...
they were reclassified from "extinct in the wild" to "critically endangered
An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
", after a reassessment in 2008,[ and from "critically endangered" to "endangered" after a 2011 reassessment.][
In 2011, Prague Zoo started a new project, Return of the Wild Horses. With the support of public and many strategic partners, yearly transports of captive-bred horses into the Great Gobi B Strictly Protected Area continued. , an estimated total of almost 400 horses existed in three free-ranging populations in the wild.][ Prague Zoo has transported horses to Mongolia in several rounds in cooperation with partners (Czech Air Force, European Breeding Programme for Przewalski's Horses, Association pour le cheval de Przewalski: Takh, Czech Development Agency, Czech Embassy in Mongolia, and others). The zoo has the longest uninterrupted history of breeding Przewalski's horses in the world and keeps the studbook of this species.
The first reintroduction into the Orenburg region on the Russian steppe occurred in 2016.
In May 2023, a herd of ten Przewalski's horses obtained from Monts D'Azur Biological Reserve in France was introduced by Rewilding Europe to the Iberian Highlands rewilding landscape in Spain, near Villanueva de Alcorón. Following an acclimatization period, the horses were released into the reserve proper in September. This introduction was intended to address the buildup of dense scrub caused by the decrease in traditional sheep grazing due to rural depopulation. The horses are intended to fill a niche similar to that of the extinct European wild horse and of contemporary domesticated ]herbivore
A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...
s by opening the landscape through low-intensity grazing and browsing, thereby enhancing biodiversity and lowering the risk of forest fire
A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire ( in Australia), dese ...
s. Future introductions are planned.
In June 2024 six mares and a stallion were reintroduced to Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
from zoos in Europe, ten years after plans were announced to do so. The operation was organised by Prague Zoo, which selected horses from various programs in Europe, which were housed at Tierpark Berlin for some months before being transported to Kazakhstan in Czech army planes.
Assisted reproduction and cloning
In the earlier decades of captivity, the insular breeding by individual zoos led to inbreeding and reduced fertility. In 1979, several American zoos began a collaborative breeding-exchange program to maximize genetic diversity.[ Recent advances in equine reproductive science have also been used to preserve and expand the gene pool. Scientists at the ]Smithsonian Institution
The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums, Education center, education and Research institute, research centers, created by the Federal government of the United States, U.S. government "for the increase a ...
's National Zoo successfully reversed a vasectomy
Vasectomy is an elective surgical procedure that results in male sterilization, often as a means of permanent contraception. During the procedure, the male vasa deferentia are cut and tied or sealed so as to prevent sperm from entering into ...
on a Przewalski horse in 2007—the first operation of its kind on this species, and possibly the first ever on any endangered species. While normally, a vasectomy may be performed on an endangered animal under limited circumstances, particularly if an individual has already produced many offspring and its genes are overrepresented in the population, scientists realized the animal in question was one of the most genetically valuable Przewalski's horses in the North American breeding program.[ The first birth by ]artificial insemination
Artificial insemination is the deliberate introduction of sperm into a female's cervix or uterine cavity for the purpose of achieving a pregnancy through in vivo fertilization by means other than sexual intercourse. It is a fertility treatment ...
occurred on 27 July 2013 at the Smithsonian Conservation Biology Institute.[
In 2020, the first cloned Przewalski's horse was born, the result of a collaboration between San Diego Zoo Global, ViaGen Equine and Revive & Restore.] The cloning
Cloning is the process of producing individual organisms with identical genomes, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction; this reproduction of an organism by itself without ...
was carried out by somatic cell nuclear transfer (SCNT), whereby a viable embryo
An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
is created by transplanting the DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
-containing nucleus of a somatic cell into an immature egg cell (oocyte
An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ger ...
) that has had its nucleus removed, producing offspring genetically identical to the somatic cell donor. Since the oocyte used was from a domestic horse, this was an example of interspecies SCNT.
The somatic cell donor was a Przewalski horse stallion named Kuporovic, born in the UK in 1975 and relocated three years later to the US, where he died in 1998. Due to concerns over the loss of genetic variation
Genetic variation is the difference in DNA among individuals or the differences between populations among the same species. The multiple sources of genetic variation include mutation and genetic recombination. Mutations are the ultimate sources ...
in the captive Przewalski's horse population, and in anticipation of the development of new cloning techniques, tissue from the stallion was cryopreserved at the San Diego Zoo's Frozen Zoo. Breeding of this individual in the 1980s had already substantially increased the genetic diversity of the captive population after he was discovered to have more unique allele
An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule.
Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), ...
s than any other horse living at the time, including otherwise lost genetic material from two of the original captive founders. To produce the clone, frozen skin fibroblast
A fibroblast is a type of cell (biology), biological cell typically with a spindle shape that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and ...
s were thawed, and grown in cell culture
Cell culture or tissue culture is the process by which cell (biology), cells are grown under controlled conditions, generally outside of their natural environment. After cells of interest have been Cell isolation, isolated from living tissue, ...
. An oocyte was collected from a domestic horse, and its nucleus replaced by a nucleus collected from a cultured Przewalski's horse fibroblast. The resulting embryo was induced to begin division. It was cultured until it reached the blastocyst
The blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the ''embryoblast'' which subsequently forms the embryo, and an outer layer of trophoblast cells called the ...
stage, then implanted into a domestic horse surrogate mare, which carried the embryo to term and delivered a foal with the Przewalski horse DNA of the long-deceased stallion.
The cloned horse was named Kurt, after Dr. Kurt Benirschke, a geneticist who developed the idea of cryopreserving genetic material from species considered to be endangered. His ideas led to creating the Frozen Zoo as a genetic library. In 2021, Kurt was relocated to the breeding herd at the San Diego Zoo Safari Park. In order to integrate him into the existing herd, Kurt was partnered with a young female named Holly, a few months older than him, in order to allow him to learn the social and communication behaviors of wild Przewalski's horses. On reaching maturity at three to four years of age, Kurt is intended to become the breeder stallion for the San Diego Zoo herd to pass Kuporovic's genes into the larger captive Przewalski's horse population and thereby increase the genetic variation of the species.
In 2023, a genetic twin of Kurt, named Ollie, was born from cloning with the help of the San Diego Zoo Global Frozen Zoo. It is the first reported case of any endangered species having more than one clone successfully produced. This individual eventually joins Kurt and Holly at the San Diego Zoo Safari Park. Due to having been conceived through the transfer of a somatic cell nucleus into an egg cell obtained from a domestic horse donor, Kurt and Ollie both display the mitochondrial genome of domestic horses instead of belonging to a Przewlaski horse mithocondrial clade. However, as mitochondrial DNA is maternally inherited, they will not pass on these domestic horse genes.
See also
* Mongolian horse (domestic)
* Mongolian wild ass
Notes
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{{Authority control
Horse subspecies
Mammals of Mongolia
Mammals of Central Asia
Mammals of East Asia
Mammals of Russia
Natural history of China
Endangered fauna of Asia
Mammals of Europe
Mammals described in 1881