Connectivity of the Asiatic wild ass population in the Mongolian Gobi

Abstract

Long-distance migrations of wildlife have been identified as important biological phenomena, but their conservation remains a major challenge. The Mongolian Gobi is one of the last refuges for the Asiatic wild ass (Equus hemionus) and other threatened migratory mammals. Using historic and current distribution ranges, population genetics, and telemetry data we assessed the connectivity of the wild ass population in the context of natural and anthropogenic landscape features and the existing network of protected areas. In the Mongolian Gobi mean biomass production is highly correlated with human and livestock density and seems to predict wild ass occurrence at the upper level. The current wild ass distribution range largely falls into areas below the 250 gC/m2/year productivity isoline, suggesting that under the present land use more productive areas have become unavailable for wild asses. Population genetics results identified two subpopulations and delineated a genetic boundary between the Dzungarian and Transaltai Gobi for which the most likely explanation are the mountain ranges separating the two areas. Home ranges and locations of 19 radiomarked wild asses support the assumed restricting effects of more productive habitats and mountain ranges and additionally point towards a barrier effect of fences. Furthermore, telemetry data shows that in the Dzungarian and Transaltai Gobi individual wild ass rarely ventured outside of the protected areas, whereas in the southeast Gobi asses only spend a small fraction of their time within the protected area network. Conserving the continuity of the wild ass population will need a landscape level approach, also including multi-use landscapes outside of protected areas, particularly in the southeast Gobi. In the southwest Gobi, allowing for openings in the border fence to China and managing the border area as an ecological corridor would connect three large protected areas together covering over 70,000 km2 of wild ass habitat.

Habitat Fragmentation by Railways as a Barrier to Great Migrations of Ungulates in Mongolia

“…An Asiatic wild ass tracked from July 2005 to February 2006 also moved along the southwestern side of the railway but did not cross it (Kaczensky et al 2006(Kaczensky et al , 2011b. The railway now likely forms the eastern edge of Fig.…”

“…The railway now likely forms the eastern edge of Fig. 14.4 Underpasses on the Ulaanbaatar-Beijing Railway the current Asiatic wild ass distribution because no wild ass has been observed on the eastern side for many years, despite the existence of suitable habitat on the northeastern side of the railway (Kaczensky et al 2011b(Kaczensky et al , 2015. Further data on tracked Mongolian gazelles have confirmed that the railway impeded 24 gazelles tracked between 2002 and 2012 from crossing to both sides ( Fig.…”

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“…It was once widespread throughout steppe and semi-desert habitats. Today it occurs only in the Dzungarian Gobi, Trans-Altai Gobi, Northern Gobi and Alashan Gobi in Mongolia 4 (Zevegmid & Dawaa, 1973;Reading et al, 2001;Feh et al, 2002;Clark et al, 2006, Kaczensky et al, 2011, and adjacent China (Chu, 2008;Bi, 2007). The Asiatic wild ass has lost about 50% of its distribution range in Mongolia during the last 70 years (Stubbe et al, 2012), and population size has decreased severely due to habitat fragmentation and loss, confl icts with livestock for pasture and water access, and poaching (Kaczensky et al, 2011;Stubbe et al, 2007).…”

“…Of particular interest in this area is the degree of genetic variability and genetic divergence between potentially isolated subpopulations. The only study in this regard was done by Kaczensky et al (2011) who examined the population genetics of the species by microsatellite DNA analysis identifying two subpopulations in the Dzungarian Gobi and in the joint Trans-Altai and Southeastern Gobi. The fi rst is exactly one of our two survey areas, and the second includes our second region in large parts.…”

“…The Asiatic wild ass has lost about 50% of its distribution range in Mongolia during the last 70 years (Stubbe et al, 2012), and population size has decreased severely due to habitat fragmentation and loss, confl icts with livestock for pasture and water access, and poaching (Kaczensky et al, 2011;Stubbe et al, 2007). Therefore, many investigations on the species in diff erent parts of Mongolia were conducted, including studies on social structure Neumann-Denzau & Denzau, 2007), population characteristics (Reading et al, 2001;Lkhagvasuren, 2007;Tsendjav & Purevsuren, 2007;Ransom et al, 2012), habitat fragmentation and loss (Kaczensky et al, 2011;Ito et al, 2013), reproduction and mortality Stubbe et al, 2012), age determination (Ansorge et al, 2007;Lkhagvasuren et al, 2013), as well as population structure and mortality (Lkhagvasuren et al, submitted). Nevertheless, for a more comprehensive evaluation of the population status of the Asiatic wild ass in Mongolia, there is still a need for more insight into the population genetics of the species.…”