The reintroduction and conservation of Przewalski’s horse/takhi
(Equus ferus przewalskii)
The reintroduction and conservation of Przewalski’s horse/takhi (Equus ferus przewalskii)
Introduction
Recent genetic analysis has concluded that the ancestors of Przewalski’s horse (Equus ferus przewalskii) (PH) split from that of the domestic horse around 45,000 years ago (Der Sarkissian et al., 2015). While the first graphical representation of horses were found in caves in Europe and appear to be of the Przewalski’s-type date back 20,000 years ago, it was a Tibetan monk who recorded the oldest known written observations of the PH circa 900 A.D. (Boyd & Houpt, 1994). First accounts of PH by western explorers in the southern Mongolian/China region did not occur until 1763, by John Bell, and then Nikolai Przewalski in 1880 (Boyd & Houpt, 1994).
Interest in the species drew the attention of zoos in Europe, which organized several expeditions to capture and bring back live specimens for their animal collections (Boyd & Houpt, 1994). From the few animals that reached western zoos alive, there were only five institutions which were able to successfully breed PH in the beginning: New York, Cincinnati, Woburn, Halle and Askania Nova (Boyd & Houpt, 1994).
Collection of PH ceased during World War II, and the last observation of a PH or “takhi” (which means “holy” in Mongolian) in the wild was in 1969 by a scientist in southwestern Mongolia (Boyd & Houpt, 1994; International Takhi Group, 2017). From the 1960s through 1996, takhi were designated as “Extinct in the Wild” (King, Boyd, Zimmermann & Kendall, 2015). Causes for their extinction have included competition with livestock for grazing areas, hunting, capture of foals, military activities, climate change including several harsh winters which were reported in 1940’s and 1950’s, as well as political and societal changes (King et al., 2015; Souris, Kaczensky, Julliard, & Walzer, 2007).
It is believed that PH originally ranged from Mongolia and northern China to Kazakhstan through the Russian Steppes (King et al., 2015). While several sites were under consideration for the reintroduction of takhi in their former range, only the Mongolians enlarged their protected areas and appeared earnest in the return of the takhi to their lands (Bouman, 2000). Reintroduction efforts have released captive bred takhis, originating from only 12 wild-caught founders, into Mongolia, and with subsequent generations of now wild-born takhis, they were listed as “endangered“ by the International Union for Conservation of Nature and Natural Resources (IUCN) with 178 mature individuals (Bouman, 2000; King et al., 2015).
Discussion
Reintroducing animals into the wild is not an easy endeavor, especially with animals that have lived in captivity for 12-14 generations. To increase their chances of success, takhi are transported to large enclosures on site and allowed to acclimate and form stable, well-bonded groups, i.e. harems, before their release into the wild (Bouman, 2000). For reintroduction sites to be considered, the location must meet several criteria: sufficient food, water, and shelter year-round, minimal predators, and no possibility of contact, and subsequent hybridization with domestic horses (Bouman, 2000, King et al., 2015). Domestic horses can also pose a disease threat (King et al., 2015; Xia et al., 2014). While the first two criteria have been easier to fulfill (Bouman, 2000),the third can be difficult in some areas, especially since domestic horses are not herded like other livestock, and herdsman allow their horses to roam freely (Van Duyne et al., 2008). Another concern for reintroduction of animals is removal of the original extinction threats, but the complete elimination of human disturbance is challenging especially in China, where recently parts of the Kalamaili Nature Reserve in Xinjiang, has been degazetted due to mining activities (Kaczensky, Lkhagvasuren, Pereladova, Hemami, & Bouskila, 2015; Xia et al., 2014).
Current reintroduction projects
Five takhi reintroduction projects are currently active, with two located in northern China and three in Mongolia (King et al., 2015). Because reintroduced takhi in both Chinese sites are herded back into enclosures and/or supplemented with food during winters, these animals are not counted as “mature individuals” when assessed by the IUCN (King, et al. 2015).
Mongolia
Reintroduction sites in Mongolia are located in the Great Gobi B Strictly Protected Area (SPA), Hustai National Park, and in the Khar Us Nuur National Park (King et al., 2015). Separate groups manage each reintroduction site and project.
Great Gobi B SPA. Since the accurate former range was not exactly established for takhi there has been controversy on whether the last sighting in 1969 near the Great Gobi B, in Southwestern Mongolia, was of an animal living at the edge of its habitat, or if this area represented optimal habitat (King et al., 2015; Souris et al., 2007). It was the conclusion by the International Takhi Group (ITG) which manages this project, that this semi-arid area was not a peripheral habitat for takhis (Kaczensky et al., 2011; King et al., 2015; Slotta-Bachmayer, Boegel, Kaczensky, Stauffer & Walzer, 2004; van Dierendonck, Bandi, Batdorj, Dugerlham, & Munkhtsog, 1996; Walzer & Kaczensky, 2011;). Transportation of animals to the Takin Tal acclimatization site in Great Gobi B then began in 1992 (King et al., 2015; Walzer & Kaczensky, 2011). However, further subsequent research conducted in the Gobi B SPA, contradicted previous beliefs and concluded that the Gobi area is indeed an “edge” habitat for takhi (Kaczensky, Ganbaatar, von Wehrden & Walzer, 2008; Walzer, 2016). Regardless, the end of 2016 saw 167 takhis in the Gobi B, which included eight individuals transported from Europe and Hustai National Park with assistance from the Prague Zoo and the Czech Air Force (ITG, 2016). Most recently four mares from the Prague Zoo were transported and released in the Takin Tal acclimatization site on June 20, 2017, to supplement the currently 190 estimated in Gobi B SPA (Hovet, June 28,2017).
Hustai National Park. While the Gobi B SPA reintroduction project gambled on their site not being an edge habitat, Hustai Nuruu, located in central Mongolia, with its mountain forest steppe ecology proved to be optimal for takhi reintroduction and to date is the most successful project (Bouman, 2000; Souris et al., 2007; Xia et al., 2014). This Dutch project began in 1992 with 84 takhi transported from open enclosures in the Netherlands and Germany (King et al., 2015; van Staalduinen & Weger, 2005) and most recent reports of over 200 takhis living in the park (Dorj, 2017). Chris Walzer who has works with the Great Gobi B project admitted after 20 years, that Hustai Nuruu was the right place for reintroduction due to high grasses and it being easier for the horses (2016).
Khomyn Tal. This project began in 2004 when the Association TAKH brought 22 takhi from France to acclimatization enclosures outside Khar Us Nuur National Park (Association TAKH, 2015; King et al., 2015; Souris et al., 2007). Supplemented with four horses from Prague Zoo in 2011 (King et al., 2015), 59 takhi were counted in 2014 (Association TAKH, 2015). Currently, these takhi are still held in acclimatization enclosures and have not been fully released (Association TAKH, 2015).
China
Currently, there are two reintroduction sites located in northern China, the Kalamaili Nature Reserve and the Dunhuang Xihu National Nature Reserve.
Kalamaili Nature Reserve. Located in the Dzungarian Gobi in the Xinjiang province, this project is managed by the Wild Horse Breeding Center (King et al., 2015; Zhang et al., 2015). Beginning in 2001, this population has increased to 121 takhi by 2013, but only one harem group is truly free year round with the other 102 individuals free to roam during the summer but herded back to acclimation enclosures during the winter (King et al., 2015; Zhang et al., 2015).
Dunhuang Xihu National Nature Reserve. Beginning in 2010, a captive breeding program managed by the Gansu Endangered Species Research has reintroduced seven takhi into the reserve, but because they are supplemented with food in the winter, they are not counted as mature individuals in the wild by the IUCN (King et al., 2015).
What was learned from reintroduction efforts? Successes and failures.
Naïve takhi in a new land. In the beginning of the reintroduction project in the Gobi B SPA, wildlife health was a challenge (Walzer, 2016). Techniques were developed to transport takhi from reserves in Europe, along with anesthesia protocols (Walzer, 2016). Within the period of the first six weeks after arrival, it was common for 3-5 takhi to die, with deaths occurring at the same time each year - end of March to the beginning of April (Walzer, 2016). Several years later, after development of necropsy protocols, it was discovered that the naïve takhi from captive breeding programs in Europe had no immunity to parasites, i.e. Babesia cabelli and T. equi, which were endemic to Mongolia and cause the tick-borne infection, piroplasmosis, in horses (King & Gurnell, 2005; Robert et al., 2005; Ruegg et al., 2006; Walzer, 2016). Since the takhi can gain immunity via infection, veterinarians created a therapy to transfer ticks to takhi and administer an anti-protozoan medication, i.e. Imidocarb, while the animals were in their acclimatization enclosures and import horses after the Mongolian tick season at the end of June (Robert et al., 2005; Walzer, 2016).
How many harems can be released from same site before there is competition? The utilization of acclimatization enclosures occurs at all reintroduction sites for typically 1-2 years before release is contemplated to ensure the takhi are prepared for life in the wild (Bouman, 2000; King et al., 2015; Painer, Kaczensky, Ganbaatar, Huber, & Walzer, 2011). Takhi are typically polygynous and live in harems with one breeding stallion who defends his mares against other males; in the acclimatization enclosures, the harems were typically set up with 3-6 mares 2-4 years of age and a stallion 4-6 years of age (Boyd & Houpt, 1994; Kaczensky et al., 2008; Slotta-Bachmayr et al., 2004). These ages were selected because these are the ages that takhi typically disperse from their family groups (Bouman, 2000). When setting up harems for enclosures, selection of individuals is such that genetic diversity is maximized to increase their chances of survival in the face disease and stochastic event threats and to lessen inbreeding (Bouman, 2000).
Post release, harems typically remained near their release site for the first year and then sometimes slowly explored and moved further away (Bouman, 2000; King & Gurnell, 2005). Some overlap of home ranges is tolerated among harems, but after repeated releases of harem groups from the same enclosure sites, competition among harems became a concern, raising the question of how many times a release enclosure could be utilized (Bouman, 2000). In 1996, it was determined to experiment if harems could be prepared in large enclosures in the Netherlands for direct release into Hustai National Park; while at first the experiment appeared promising, ultimately it resulted in the death of three animals several months later, leaving one surviving mare (Bouman, 2000). The result of this experiment was the conclusion to build new release enclosures in unoccupied areas of the park (Bouman, 2000).
Body condition concerns, pre- and post-release. Brabender, Zimmermann, and Hampson (2016) studied the body condition of 33 takhi living in a semi-natural habitat in Hungary over the course of a year and found a seasonal fluctuation, which they associated to changes in pasture quality. Stallions demonstrated lower body scores than mares, which the authors attributed to energy investment in defending their mares (Brabender et al., 2016). Unlike in feral domestic horses, Brabender et al.(2016) found no decrease in the body condition of takhi mares pre- and post- foal production, which has similarly been reported in Mongolia (Souris et al., 2007). Body scores of released takhis, which survive their first year in Mongolia, have been reported as improved over pre-release conditions (Bouman, 2000).
Stochastic events: ‘Dzud’. One of the extinction threats to a small population of species with diminished genetic variability, such as reintroduced takhi, is the occurrence of stochastic, catastrophic events (Kaczensky et al., 2011; Slotta-Bachmayr et al., 2004). Catastrophic winters, ‘dzud’, have occurred in the Gobi region, characterized by tall snowdrifts and storms, severe cold, and a subsequent summer drought (Robert et al., 2005). The extinction of takhi is believed to be partly attributed to the severe winter conditions in the late 1940s and 1950s (King et al., 2015). The winter of 2000-2001, characterized with dzud conditions, contributed to the death of takhi, by weakening the takhi they became infected with strangles, which they likely obtained from prior contact with domestic horses (Robert et al., 2005). These horses in their weakened condition died from infection and/or became easy prey for wolves, which were first blamed for the takhi deaths (Robert et al., 2005; Walzer, 2016).
The winter of 2009-2010, saw another dzud event with millions of livestock lost, and a crash of takhi population (Kaczensky et al., 2011). In December 2009, there were 138 takhi reportedly living in the Gobi B SPA, but by April 2010, only 49 individuals were found alive (King et al., 2015). Kaczensky et al. (2011) reported that mares appear to be less vulnerable than stallions in succumbing to dzud conditions. However, as Brabender et al. (2016) demonstrated in their study, stallions demonstrated lower body condition scores than mares even under optimal conditions, which they attributed to increased energy usage to defend their mares . A contributing factor to the loss of reintroduced takhi is their tendency to not explore their new surroundings; this lack of spatial knowledge of their habitat can limit their success during local catastrophic events (Kaczensky et al., 2011). In addition to the immediate death of animals to dzud conditions, the resulting loss to populations is increasingly hampered by lowered fecundity the season following a dzud (Slotta-Bachmayr et al., 2004).
Due to the crash of 2009-2010, there is increased cooperation among the reintroduction projects, and transfer of takhi from Hustai National Park, which suffered less from the storms, occurred to assist in the recovery of the Gobi B population (Kaczensky et al., 2011). Further collaboration and cooperation among the different reintroduction sites has been suggested as a conservation action to manage wild takhis as one population (Kaczensky et al., 2011; King et al, 2015).
Habitat requirements, use and limiting factors
Water. A major limiting factor for takhi is daily availability to a quality water source (Bouman, 2000; Walzer, 2016). While studying possible competition between takhi and Asiatic Wild Ass, or ‘khulan’ in the Kalamaili Nature Reserve, Zhang et al.(2015) reported that takhis drank twice a day from lower salinity sources when compared to khulans. The khulan reportedly drink every other day and tolerate high salinity water sources (Zhang et al., 2015). All reintroduction sites are located near permanent water sources.
Vegetation. In the Gobi B SPA, takhi have been restricted to the best patches of forage along rivers and oases, and are unable to use some desert shrubs that the khulan can utilize (Walzer, 2016). When comparing resource selection among takhi and khulan, Kaczensky et al.(2008) found vegetation to be the best predictor for resource choice by takhi, greater than geography or even distance to water. However, they also found that the distance to their water source was much lower than khulan, which supports the limiting effect reported by Zhang et al. (2015) that water availability has on takhi habitat selection .
Habitat Use. Studies of takhis released in the wild have shown that habitat use is strongly influenced by temperature and the presence of flies (King & Gurnell, 2005; King & Gurnell, 2010; Souris et al., 2007). Observations of takhis commonly report grazing in the early morning and late afternoon in valleys, which offer the best available vegetation, and when temperatures rise, they move to higher elevations to rest on ridges even when they offered no vegetation (King & Gurnell, 2005; King & Gurnell, 2010; Souris et al., 2007; van Dierendonck et al., 1996).
Competition with the sympatric khulan. In the semi-arid environment of the Gobi, takhi coexist with the khulan. When Kaczensky et al. (2008) studied resource selection by the two sympatric species in Mongolia, they concluded that no competition was observed between the two, with takhi drinking during the day and khulan during night time. This conflicts with what Zhang et al. (2015) observed when studying water source selection among the two species in the Chinese side of the Gobi. The researchers observed instances of khulan made to wait to drink while takhi drank from the best quality available water sources, showing that there is competition among the two species (Zhang et al., 2015).
Conclusion
Of the five reintroduction sites and projects, the Dutch project at Hustai National Park has been the most successful. From 1992 -2002, 84 takhi originating from the Netherlands were reintroduced into the park, and most current reports are of 220 takhi living in the park (Hustai National Park, 2013; King et al., 2015; Xia et al., 2014). Hustai National Park has translocated takhi to other reintroduction sites. Nevertheless, the question arises, when and how do we quantify the reintroduction of takhi as a success? Is it a final population number, and what is that number?
Some of the reintroduction projects still require supplementation of takhi from captivity or other sites. With the inherent limited genetic diversity of the species, and its small sub-populations it has already been observed that stochastic events, such as dzud winters, can cause sub-populations to crash. Slotta-Bachmayr et al (2004) when modeling the population viability of reintroduced takhi in the Gobi B found that under high levels of catastrophes, which is more likely with climate change, it was unreliable to predict when supplementation could be halted nor determine a minimal viable population. In the meantime, it has been recommended that takhi in Mongolia be managed as one population, with management plans to transfer individuals from one site to another to maximize genetic variability (King et al., 2015).
In addition to climate change and small population size, several other threats remain to takhi living in the wild, one threat specific to takhi is the domestic horse. Besides competition for pastures, contact with horses can introduce disease, such as piroplasmosis and strangles, while another threat is hybridization. Even though takhi and domestic horses have a different number of chromosomes (takhi 2n=66, domestic horse 2n=64), they do hybridize and bear fertile offspring (King et al., 2015). Contact between the two has been suggested to be kept to a minimum, as well as the development of a protocol for how to manage hybridization (King et al., 2015).
Overgrazing is specified as a threat to all ungulates living in reintroduction areas. Extraction industries, i.e. mining, is now a large threat to animals living in the region of the Gobi. Mining increases human disturbance and threatens water sources for animals.
Wolf predation has been claimed as a threat to takhi, as well as livestock. When studying wolf predation in Hustai National Park, van Duyne et al (2009) recommended the solution, that since red deer was the favorite prey item, that conservation and propagation of red deer would not only benefit takhi but livestock as well, and improve relationships with herdsman.
Many studies mention the inclusion of stakeholders as imperative to the success of reintroduction projects (Bouman, 2000; King et al., 2015; Walzer & Kaczensky, 2011; Xia et al., 2014). Inclusion of stakeholders is imperative not only for projects in Mongolia, but it is mentioned as a requirement and action in almost every global conservation issue. Still, Walzer (2016) feels that, “we have failed miserably”, with the success rate being very small in training and involving stakeholders (in the Gobi). The wildlife biologist at Hustai National Park, Usukhjargal “Usko” Dorj, stated a similar sentiment that much is left to do when involving stakeholders when describing programs for livestock herders living in the buffer zone of the national park in a negative connotation (2017). Walzer (2016) recommends that social sciences must be involved from day one, to help diagnose societal mechanisms and learn how to change them, to create potential drivers of social change, and that more investment in people is key. Cooperation among the reintroduction project groups, researchers among different disciplines, studying different species in the ecosystem and the stakeholders is crucial for the conservation of takhi and its landscape.
References
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Brabender, K., Zimmermann, W., & Hampson, B. (2016). Seasonal changes in body condition of Przewalski’s horses in a seminatural habitat. Journal of Equine Veterinary Science, 42, 73-76.
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Hovet, J. (2017, June 28). Environment: From Prague to Mongolia, wild horses return to the steppes. Reuters. Retrieved from https://www.reuters.com/article/us-mongolia-horses-idUSKBN19I229
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Kaczensky, P., Ganbaatar, O., von Wehrden, H., & Walzer, C. (2008). Resource selection by sympatric wild equids in the Mongolian Gobi. Journal of Applied Ecology, 45, 1762-1769.
Kaczensky, P., Ganbaatar, O., Altansukh, N., Enkhsaikhan, Stauffer, C., & Walzer, C. (2011). The danger of having all your eggs in one basket-Winter crash of the rei-introduced Przewalski’s horses in the Mongolian Gobi. PLoS ONE, 6(12). E28057. doi:10.1371/journal.pone.0028057
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Ruegg, S. R., Torgenson, P. R., Doherr, M.G., Deplazes, P., Bose, R., Robert, N., & Walzer, C. (2006). Equine piroplasmosis at the reintroduction site of the Przewalski’s horse (Equus ferus przewalskii) in Mongolia. Journal of Wildlife Diseases, 42(3), 518-526.
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Souris, A., Kaczensky, P., Julliard, R., & Walzer, C. (2007). Time budget-, behavioral synchrony- and body score development of a newly released Przewalski’s horse group Equus ferus przewalskii, in the Great Gobi B strictly protected area in SW Mongolia. Applied Animal Behaviour Science, 107, 307-321.
van Dierendonck, M.C., Bandi, N., Batdorj, D., Dugerlham, S., & Munkhtsog, B. (1996). Behavioural observations of reintroduced takhi or Przewalski horses (Equus ferus przewalskii) in Mongolia. Applied Animal Behaviour Science, 50, 95-114.
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Introduction
Recent genetic analysis has concluded that the ancestors of Przewalski’s horse (Equus ferus przewalskii) (PH) split from that of the domestic horse around 45,000 years ago (Der Sarkissian et al., 2015). While the first graphical representation of horses were found in caves in Europe and appear to be of the Przewalski’s-type date back 20,000 years ago, it was a Tibetan monk who recorded the oldest known written observations of the PH circa 900 A.D. (Boyd & Houpt, 1994). First accounts of PH by western explorers in the southern Mongolian/China region did not occur until 1763, by John Bell, and then Nikolai Przewalski in 1880 (Boyd & Houpt, 1994).
Interest in the species drew the attention of zoos in Europe, which organized several expeditions to capture and bring back live specimens for their animal collections (Boyd & Houpt, 1994). From the few animals that reached western zoos alive, there were only five institutions which were able to successfully breed PH in the beginning: New York, Cincinnati, Woburn, Halle and Askania Nova (Boyd & Houpt, 1994).
Collection of PH ceased during World War II, and the last observation of a PH or “takhi” (which means “holy” in Mongolian) in the wild was in 1969 by a scientist in southwestern Mongolia (Boyd & Houpt, 1994; International Takhi Group, 2017). From the 1960s through 1996, takhi were designated as “Extinct in the Wild” (King, Boyd, Zimmermann & Kendall, 2015). Causes for their extinction have included competition with livestock for grazing areas, hunting, capture of foals, military activities, climate change including several harsh winters which were reported in 1940’s and 1950’s, as well as political and societal changes (King et al., 2015; Souris, Kaczensky, Julliard, & Walzer, 2007).
It is believed that PH originally ranged from Mongolia and northern China to Kazakhstan through the Russian Steppes (King et al., 2015). While several sites were under consideration for the reintroduction of takhi in their former range, only the Mongolians enlarged their protected areas and appeared earnest in the return of the takhi to their lands (Bouman, 2000). Reintroduction efforts have released captive bred takhis, originating from only 12 wild-caught founders, into Mongolia, and with subsequent generations of now wild-born takhis, they were listed as “endangered“ by the International Union for Conservation of Nature and Natural Resources (IUCN) with 178 mature individuals (Bouman, 2000; King et al., 2015).
Discussion
Reintroducing animals into the wild is not an easy endeavor, especially with animals that have lived in captivity for 12-14 generations. To increase their chances of success, takhi are transported to large enclosures on site and allowed to acclimate and form stable, well-bonded groups, i.e. harems, before their release into the wild (Bouman, 2000). For reintroduction sites to be considered, the location must meet several criteria: sufficient food, water, and shelter year-round, minimal predators, and no possibility of contact, and subsequent hybridization with domestic horses (Bouman, 2000, King et al., 2015). Domestic horses can also pose a disease threat (King et al., 2015; Xia et al., 2014). While the first two criteria have been easier to fulfill (Bouman, 2000),the third can be difficult in some areas, especially since domestic horses are not herded like other livestock, and herdsman allow their horses to roam freely (Van Duyne et al., 2008). Another concern for reintroduction of animals is removal of the original extinction threats, but the complete elimination of human disturbance is challenging especially in China, where recently parts of the Kalamaili Nature Reserve in Xinjiang, has been degazetted due to mining activities (Kaczensky, Lkhagvasuren, Pereladova, Hemami, & Bouskila, 2015; Xia et al., 2014).
Current reintroduction projects
Five takhi reintroduction projects are currently active, with two located in northern China and three in Mongolia (King et al., 2015). Because reintroduced takhi in both Chinese sites are herded back into enclosures and/or supplemented with food during winters, these animals are not counted as “mature individuals” when assessed by the IUCN (King, et al. 2015).
Mongolia
Reintroduction sites in Mongolia are located in the Great Gobi B Strictly Protected Area (SPA), Hustai National Park, and in the Khar Us Nuur National Park (King et al., 2015). Separate groups manage each reintroduction site and project.
Great Gobi B SPA. Since the accurate former range was not exactly established for takhi there has been controversy on whether the last sighting in 1969 near the Great Gobi B, in Southwestern Mongolia, was of an animal living at the edge of its habitat, or if this area represented optimal habitat (King et al., 2015; Souris et al., 2007). It was the conclusion by the International Takhi Group (ITG) which manages this project, that this semi-arid area was not a peripheral habitat for takhis (Kaczensky et al., 2011; King et al., 2015; Slotta-Bachmayer, Boegel, Kaczensky, Stauffer & Walzer, 2004; van Dierendonck, Bandi, Batdorj, Dugerlham, & Munkhtsog, 1996; Walzer & Kaczensky, 2011;). Transportation of animals to the Takin Tal acclimatization site in Great Gobi B then began in 1992 (King et al., 2015; Walzer & Kaczensky, 2011). However, further subsequent research conducted in the Gobi B SPA, contradicted previous beliefs and concluded that the Gobi area is indeed an “edge” habitat for takhi (Kaczensky, Ganbaatar, von Wehrden & Walzer, 2008; Walzer, 2016). Regardless, the end of 2016 saw 167 takhis in the Gobi B, which included eight individuals transported from Europe and Hustai National Park with assistance from the Prague Zoo and the Czech Air Force (ITG, 2016). Most recently four mares from the Prague Zoo were transported and released in the Takin Tal acclimatization site on June 20, 2017, to supplement the currently 190 estimated in Gobi B SPA (Hovet, June 28,2017).
Hustai National Park. While the Gobi B SPA reintroduction project gambled on their site not being an edge habitat, Hustai Nuruu, located in central Mongolia, with its mountain forest steppe ecology proved to be optimal for takhi reintroduction and to date is the most successful project (Bouman, 2000; Souris et al., 2007; Xia et al., 2014). This Dutch project began in 1992 with 84 takhi transported from open enclosures in the Netherlands and Germany (King et al., 2015; van Staalduinen & Weger, 2005) and most recent reports of over 200 takhis living in the park (Dorj, 2017). Chris Walzer who has works with the Great Gobi B project admitted after 20 years, that Hustai Nuruu was the right place for reintroduction due to high grasses and it being easier for the horses (2016).
Khomyn Tal. This project began in 2004 when the Association TAKH brought 22 takhi from France to acclimatization enclosures outside Khar Us Nuur National Park (Association TAKH, 2015; King et al., 2015; Souris et al., 2007). Supplemented with four horses from Prague Zoo in 2011 (King et al., 2015), 59 takhi were counted in 2014 (Association TAKH, 2015). Currently, these takhi are still held in acclimatization enclosures and have not been fully released (Association TAKH, 2015).
China
Currently, there are two reintroduction sites located in northern China, the Kalamaili Nature Reserve and the Dunhuang Xihu National Nature Reserve.
Kalamaili Nature Reserve. Located in the Dzungarian Gobi in the Xinjiang province, this project is managed by the Wild Horse Breeding Center (King et al., 2015; Zhang et al., 2015). Beginning in 2001, this population has increased to 121 takhi by 2013, but only one harem group is truly free year round with the other 102 individuals free to roam during the summer but herded back to acclimation enclosures during the winter (King et al., 2015; Zhang et al., 2015).
Dunhuang Xihu National Nature Reserve. Beginning in 2010, a captive breeding program managed by the Gansu Endangered Species Research has reintroduced seven takhi into the reserve, but because they are supplemented with food in the winter, they are not counted as mature individuals in the wild by the IUCN (King et al., 2015).
What was learned from reintroduction efforts? Successes and failures.
Naïve takhi in a new land. In the beginning of the reintroduction project in the Gobi B SPA, wildlife health was a challenge (Walzer, 2016). Techniques were developed to transport takhi from reserves in Europe, along with anesthesia protocols (Walzer, 2016). Within the period of the first six weeks after arrival, it was common for 3-5 takhi to die, with deaths occurring at the same time each year - end of March to the beginning of April (Walzer, 2016). Several years later, after development of necropsy protocols, it was discovered that the naïve takhi from captive breeding programs in Europe had no immunity to parasites, i.e. Babesia cabelli and T. equi, which were endemic to Mongolia and cause the tick-borne infection, piroplasmosis, in horses (King & Gurnell, 2005; Robert et al., 2005; Ruegg et al., 2006; Walzer, 2016). Since the takhi can gain immunity via infection, veterinarians created a therapy to transfer ticks to takhi and administer an anti-protozoan medication, i.e. Imidocarb, while the animals were in their acclimatization enclosures and import horses after the Mongolian tick season at the end of June (Robert et al., 2005; Walzer, 2016).
How many harems can be released from same site before there is competition? The utilization of acclimatization enclosures occurs at all reintroduction sites for typically 1-2 years before release is contemplated to ensure the takhi are prepared for life in the wild (Bouman, 2000; King et al., 2015; Painer, Kaczensky, Ganbaatar, Huber, & Walzer, 2011). Takhi are typically polygynous and live in harems with one breeding stallion who defends his mares against other males; in the acclimatization enclosures, the harems were typically set up with 3-6 mares 2-4 years of age and a stallion 4-6 years of age (Boyd & Houpt, 1994; Kaczensky et al., 2008; Slotta-Bachmayr et al., 2004). These ages were selected because these are the ages that takhi typically disperse from their family groups (Bouman, 2000). When setting up harems for enclosures, selection of individuals is such that genetic diversity is maximized to increase their chances of survival in the face disease and stochastic event threats and to lessen inbreeding (Bouman, 2000).
Post release, harems typically remained near their release site for the first year and then sometimes slowly explored and moved further away (Bouman, 2000; King & Gurnell, 2005). Some overlap of home ranges is tolerated among harems, but after repeated releases of harem groups from the same enclosure sites, competition among harems became a concern, raising the question of how many times a release enclosure could be utilized (Bouman, 2000). In 1996, it was determined to experiment if harems could be prepared in large enclosures in the Netherlands for direct release into Hustai National Park; while at first the experiment appeared promising, ultimately it resulted in the death of three animals several months later, leaving one surviving mare (Bouman, 2000). The result of this experiment was the conclusion to build new release enclosures in unoccupied areas of the park (Bouman, 2000).
Body condition concerns, pre- and post-release. Brabender, Zimmermann, and Hampson (2016) studied the body condition of 33 takhi living in a semi-natural habitat in Hungary over the course of a year and found a seasonal fluctuation, which they associated to changes in pasture quality. Stallions demonstrated lower body scores than mares, which the authors attributed to energy investment in defending their mares (Brabender et al., 2016). Unlike in feral domestic horses, Brabender et al.(2016) found no decrease in the body condition of takhi mares pre- and post- foal production, which has similarly been reported in Mongolia (Souris et al., 2007). Body scores of released takhis, which survive their first year in Mongolia, have been reported as improved over pre-release conditions (Bouman, 2000).
Stochastic events: ‘Dzud’. One of the extinction threats to a small population of species with diminished genetic variability, such as reintroduced takhi, is the occurrence of stochastic, catastrophic events (Kaczensky et al., 2011; Slotta-Bachmayr et al., 2004). Catastrophic winters, ‘dzud’, have occurred in the Gobi region, characterized by tall snowdrifts and storms, severe cold, and a subsequent summer drought (Robert et al., 2005). The extinction of takhi is believed to be partly attributed to the severe winter conditions in the late 1940s and 1950s (King et al., 2015). The winter of 2000-2001, characterized with dzud conditions, contributed to the death of takhi, by weakening the takhi they became infected with strangles, which they likely obtained from prior contact with domestic horses (Robert et al., 2005). These horses in their weakened condition died from infection and/or became easy prey for wolves, which were first blamed for the takhi deaths (Robert et al., 2005; Walzer, 2016).
The winter of 2009-2010, saw another dzud event with millions of livestock lost, and a crash of takhi population (Kaczensky et al., 2011). In December 2009, there were 138 takhi reportedly living in the Gobi B SPA, but by April 2010, only 49 individuals were found alive (King et al., 2015). Kaczensky et al. (2011) reported that mares appear to be less vulnerable than stallions in succumbing to dzud conditions. However, as Brabender et al. (2016) demonstrated in their study, stallions demonstrated lower body condition scores than mares even under optimal conditions, which they attributed to increased energy usage to defend their mares . A contributing factor to the loss of reintroduced takhi is their tendency to not explore their new surroundings; this lack of spatial knowledge of their habitat can limit their success during local catastrophic events (Kaczensky et al., 2011). In addition to the immediate death of animals to dzud conditions, the resulting loss to populations is increasingly hampered by lowered fecundity the season following a dzud (Slotta-Bachmayr et al., 2004).
Due to the crash of 2009-2010, there is increased cooperation among the reintroduction projects, and transfer of takhi from Hustai National Park, which suffered less from the storms, occurred to assist in the recovery of the Gobi B population (Kaczensky et al., 2011). Further collaboration and cooperation among the different reintroduction sites has been suggested as a conservation action to manage wild takhis as one population (Kaczensky et al., 2011; King et al, 2015).
Habitat requirements, use and limiting factors
Water. A major limiting factor for takhi is daily availability to a quality water source (Bouman, 2000; Walzer, 2016). While studying possible competition between takhi and Asiatic Wild Ass, or ‘khulan’ in the Kalamaili Nature Reserve, Zhang et al.(2015) reported that takhis drank twice a day from lower salinity sources when compared to khulans. The khulan reportedly drink every other day and tolerate high salinity water sources (Zhang et al., 2015). All reintroduction sites are located near permanent water sources.
Vegetation. In the Gobi B SPA, takhi have been restricted to the best patches of forage along rivers and oases, and are unable to use some desert shrubs that the khulan can utilize (Walzer, 2016). When comparing resource selection among takhi and khulan, Kaczensky et al.(2008) found vegetation to be the best predictor for resource choice by takhi, greater than geography or even distance to water. However, they also found that the distance to their water source was much lower than khulan, which supports the limiting effect reported by Zhang et al. (2015) that water availability has on takhi habitat selection .
Habitat Use. Studies of takhis released in the wild have shown that habitat use is strongly influenced by temperature and the presence of flies (King & Gurnell, 2005; King & Gurnell, 2010; Souris et al., 2007). Observations of takhis commonly report grazing in the early morning and late afternoon in valleys, which offer the best available vegetation, and when temperatures rise, they move to higher elevations to rest on ridges even when they offered no vegetation (King & Gurnell, 2005; King & Gurnell, 2010; Souris et al., 2007; van Dierendonck et al., 1996).
Competition with the sympatric khulan. In the semi-arid environment of the Gobi, takhi coexist with the khulan. When Kaczensky et al. (2008) studied resource selection by the two sympatric species in Mongolia, they concluded that no competition was observed between the two, with takhi drinking during the day and khulan during night time. This conflicts with what Zhang et al. (2015) observed when studying water source selection among the two species in the Chinese side of the Gobi. The researchers observed instances of khulan made to wait to drink while takhi drank from the best quality available water sources, showing that there is competition among the two species (Zhang et al., 2015).
Conclusion
Of the five reintroduction sites and projects, the Dutch project at Hustai National Park has been the most successful. From 1992 -2002, 84 takhi originating from the Netherlands were reintroduced into the park, and most current reports are of 220 takhi living in the park (Hustai National Park, 2013; King et al., 2015; Xia et al., 2014). Hustai National Park has translocated takhi to other reintroduction sites. Nevertheless, the question arises, when and how do we quantify the reintroduction of takhi as a success? Is it a final population number, and what is that number?
Some of the reintroduction projects still require supplementation of takhi from captivity or other sites. With the inherent limited genetic diversity of the species, and its small sub-populations it has already been observed that stochastic events, such as dzud winters, can cause sub-populations to crash. Slotta-Bachmayr et al (2004) when modeling the population viability of reintroduced takhi in the Gobi B found that under high levels of catastrophes, which is more likely with climate change, it was unreliable to predict when supplementation could be halted nor determine a minimal viable population. In the meantime, it has been recommended that takhi in Mongolia be managed as one population, with management plans to transfer individuals from one site to another to maximize genetic variability (King et al., 2015).
In addition to climate change and small population size, several other threats remain to takhi living in the wild, one threat specific to takhi is the domestic horse. Besides competition for pastures, contact with horses can introduce disease, such as piroplasmosis and strangles, while another threat is hybridization. Even though takhi and domestic horses have a different number of chromosomes (takhi 2n=66, domestic horse 2n=64), they do hybridize and bear fertile offspring (King et al., 2015). Contact between the two has been suggested to be kept to a minimum, as well as the development of a protocol for how to manage hybridization (King et al., 2015).
Overgrazing is specified as a threat to all ungulates living in reintroduction areas. Extraction industries, i.e. mining, is now a large threat to animals living in the region of the Gobi. Mining increases human disturbance and threatens water sources for animals.
Wolf predation has been claimed as a threat to takhi, as well as livestock. When studying wolf predation in Hustai National Park, van Duyne et al (2009) recommended the solution, that since red deer was the favorite prey item, that conservation and propagation of red deer would not only benefit takhi but livestock as well, and improve relationships with herdsman.
Many studies mention the inclusion of stakeholders as imperative to the success of reintroduction projects (Bouman, 2000; King et al., 2015; Walzer & Kaczensky, 2011; Xia et al., 2014). Inclusion of stakeholders is imperative not only for projects in Mongolia, but it is mentioned as a requirement and action in almost every global conservation issue. Still, Walzer (2016) feels that, “we have failed miserably”, with the success rate being very small in training and involving stakeholders (in the Gobi). The wildlife biologist at Hustai National Park, Usukhjargal “Usko” Dorj, stated a similar sentiment that much is left to do when involving stakeholders when describing programs for livestock herders living in the buffer zone of the national park in a negative connotation (2017). Walzer (2016) recommends that social sciences must be involved from day one, to help diagnose societal mechanisms and learn how to change them, to create potential drivers of social change, and that more investment in people is key. Cooperation among the reintroduction project groups, researchers among different disciplines, studying different species in the ecosystem and the stakeholders is crucial for the conservation of takhi and its landscape.
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