New Railways May Threaten the Largest Population of Asiatic Wild Ass in the World

Authors: Petra Kaczensky, Inland Norway University of Applied Sciences, Department of Forestry and Wildlife Management, Norway & Research Institute of Wildlife Ecology (FIWI), University of Veterinary Medicine Vienna, Austria; Bayarbaatar Buuveibaatar, Wildlife Conservation Society (WCS), Mongolia; Chris Walzer, WCS, USA & Research Institute of Wildlife Ecology (FIWI), University of Veterinary Medicine Vienna, Austria; Kirk A. Olson, WCS, Mongolia.


Bonn, 5 January 2023 - The Asiatic Wild Ass (Equus hemionus) or Khulan are great migrants, who travel in a nomadic pattern in search of food and water, and to avoid unfavourable weather conditions. The range of the species has shrunk dramatically in recent decades as its populations went extinct in over 15 countries. According to the IUCN red list assessment, Equus hemionus is assessed as near threatened and its free ranging populations currently occur in 17 more or less isolated populations on the territories of eight countries. The global population is estimated at 77,000 animals, updated with the most recent population estimates for Mongolia.

The species is listed on Appendix II of CMS and is covered by the Central Asian Mammals Initiative (CAMI). At present most Khulan occur within the CAMI region in: China, India, Iran, Kazakhstan (Status: Reintroduced), Mongolia, Turkmenistan, and Uzbekistan (Status: Reintroduced). By far the largest subpopulation of Khulan, estimated at about 51,700 animals, is found in the southern Gobi of Mongolia (Buuveibaatar et al., 2019, unpublished data). Large-scale, nomadic movements are key to the survival of Khulan in the harsh and highly variable ecosystem of the Gobi.

Current linear infrastructure development in Mongolia poses a major threat to Khulan’s large-scale movements. If not mitigated, these developments will fragment the Khulan range thereby increasing vulnerability of the largest remaining population of the species.

In September 2022, an international research team fitted GPS satellite collars onto 29 Khulan in Mongolia’s South Gobi Region in order to study how linear infrastructure and other human activities are affecting the way these animals move across the landscape. The project is funded by Oyu Tolgoi LLC, a Mongolian gold and copper mining company as part of its core biodiversity monitoring programme and is implemented by the Wildlife Conservation Society (WCS) in cooperation with other partners. This is the fourth campaign to capture and collar Khulan since 2013, allowing to monitor and study the movements of nearly 100 animals.

Since the last collaring season in September 2018, three new railroads, namely the Tavan Tolgoi – Gashuun Suhait railway (267 km), the Zuunbayan-Khangi railway (226 km), and the Tavan Tolgoi-Zuunbayan railway (416 km), were built across the Khulan range in the South Gobi to improve market access to China and beyond. The first two are aligned along a north-south axis, while the latter is aligned along an east-west axis from the Tavan Tolgoi Coal mine connecting to the Trans Mongolian railway (Fig. 1). 

The three railways are likely to be a significant or even a complete barrier to Khulan movements, especially if fenced, unless appropriate mitigation measures are put in place. It is known that impermeable barriers can cause the range of Khulan to shrink. For example, the corridor fencing along the Trans Mongolian railway has been a near total barrier for Khulan since its construction in the 1950’s. As a result, today the Trans Mongolian railway marks the eastern boundary of the Khulan range.

Regrettably, the new Tavan Tolgoi – Gashuun Suhait railway was fenced in 2022 and there is a possibility that the other new railroads will also be fenced. Almost immediately after completion of the new railway fencing, Khulan and other migratory wild ungulates have been observed trapped in the wire fence. Moreover, field observations during the collaring mission and GPS movement data of collared Khulan from the first three weeks after collaring already suggest a significant barrier effect of the new railways:

  • Khulan appear to aggregate along certain stretches of the Tavan Tolgoi-Zuunbayan railway, seemingly stopped by the steep embankment and possibly ongoing construction activity (Fig. 2).
  • Khulan trails and dung run parallel to the fenced Tavan Tolgoi-Sukhait Gashuun railway, suggesting parallel walking of Khulan along the fence.
  • One collared Khulan walked three times along a 28 km stretch of the newly fenced Tavan Tolgoi-Sukhait Gashuun railway without crossing (Fig. 3).
  • Three collared Khulan walked from 20-55 km parallel to the Tavan Tolgoi-Sukhait Gashuun railway before crossing, and one Khulan walked 30 km parallel to the Zuunbayan-Khangi railway before crossing (Fig. 3).


As these animals struggle to cross the railway, they expend time and energy to circumnavigate these novel obstacles and sometimes fail to access their vital resources. However, this barrier effect can be alleviated if adequate wildlife crossing structures, particularly along segments of the railroad that are fenced or where the embankment is extraordinarily steep, are integrated in the design of the railroad and accompanying structures. Currently there are structures that allow wildlife to cross, but these are primarily the result of other engineering requirements (e.g., to cross riverbeds or allow water run-off) or allow vehicle crossings. These structures are often not suitable for Khulan and other migratory species occurring in the area, such as Goitered and Mongolian Gazelles, and Argali Sheep.

Therefore, there is an urgent need to re-think the current infrastructure policy that is guiding the development of Mongolian railroads to accommodate the needs of migratory wildlife. This situation can be improved with relatively simple measures. For example, fencing needs to be avoided or at least reduced to areas near settlements and railway stations. Dedicated wildlife crossings need to be installed at regular intervals. Without these measures, Mongolia risks to lose its unique migratory ungulates.

Mongolia’s work on mitigating infrastructure effects on wildlife has pioneered the CMS workstream on this topic. It has been in the focus of two CMS workshops which addressed the effects of infrastructure on migratory mammals in Central Asia.  As the result of the two workshops, Mongolia adopted the national “Ulaanbaatar Action Plan on Wildlife-friendly Infrastructure” in 2015. The plan was based on the Guidelines for Addressing the Impact of Linear Infrastructure on Large Migratory Mammals in Central Asia, adopted by CMS at the 11th Meeting of the Conference of the Parties in 2014.

The workshop was jointly organized by CMS, German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety, the associated Federal Agency for Nature Conservation, and the Mongolian office of the German Development Cooperation Agency (GIZ). Therefore, the Mongolian government and experts have already gathered experience of working on mitigating the impacts of infrastructure on large mammals, which can help address the new challenges.

Finally, the CMS Conference of the Parties at its thirteenth meeting recognized the significant impact infrastructure has on migratory species and their habitats and called for the establishment of a working group under its Scientific Council to compile standards and guidelines and to assess the needs of Parties in better fulfilling their obligations. The working group formulated a number of recommendations by identifying missing links between the environmental, finance, and planning sectors that should be overcome through improvements in international and national governance structures. The Working Group’s recommendations will be considered by the Sixth Meeting of the Sessional Committee of the CMS Scientific Council then by the Fourteenth Meeting of the Conference of the Parties.

Last updated on 17 February 2023

Habitat loss and degradation
Infrastructure and service corridors
Equus hemionus
Species group: 
Terrestrial mammals