Ibex & Argali share the spotlight in Mongolia’s Tost Reserve

A recently published paper by SLT researcher Chagsaldulam Odonjavkhlan (Chagsaa) explores what allows similar herbivore species, a wild goat and a wild sheep, to coexist with little or no competition over resources. Her research examines the mechanisms of coexistence between two snow leopard prey species, the ibex and the argali.

When we think of mountain ungulate species, it is often in relation to their role as prey for snow leopards. Indeed, this is an important factor in why we study and discuss them, but that does not mean they are undeserving of their own spotlight. Chagsaa’s recent study focuses on two of Mongolia’s most charismatic ungulates: the ibex and argali.

Ibex (pictured below) are wild goats, the species in Asia’s mountains called the Siberian Ibex. They typically live above the tree line.  A male Ibex’s most distinctive feature is undoubtedly his long, scimitar-shaped horns which can sometimes grow to nearly five feet long, and it is the largest species of wild goats in the world. 

A male Ibex, Tost Reserve

Argali (below) are a species of wild sheep, and the largest of all wild sheep or goat species. Male argali have large, spiraling horns that can grow up to nearly 6 feet long and weigh over 50 pounds!

a male Argali, Tost Reserve

Chagsaa’s recently published research assessed how these two ungulate species – both herbivores feeding on plants – coexist in parts of the snow leopard range. They must both rely on the relatively scarce plants growing in the mountainous desert landscape of Tost. As Chagsaa posits, similar species which share an ecological niche in a resource-limited habitat are often prone to competition. An initial assumption might be that ibex and argali in Mongolia’s resource-scare South Gobi fall into this pattern, and so her study explores what allows them to share the desert habitat.

Her study, which was a part of her Master’s Dissertation, was conducted in the Tost Mountains, where both species are present. Over a few cold winter months, Chagsaa and Tost’s community rangers scouted 63 predetermined areas within Tost Mountains, and walked on average 7.8km per area, covering a collective 492 kilometers over the duration of the study. During their expeditions, the team logged encounters with both ibex and argali and recorded relevant information about herd size, terrain ruggedness and other relevant variables.

“Winter brings snow and strong winds…Sometimes I walked with a [Tost] ranger and sometimes [I] walked alone. Although I grew up near wildlife, it was difficult when I walked alone, as if I was alone on Mars. However, when I saw animals like fox, wolf, argali, ibex and sometimes a herder, all these things inspired me to overcome any kinds of difficulties. I successfully finished my fieldwork with [help from] great rangers.”

Chagsaa hypothesized that, as wild sheep are prone to do, argali were likely to be using more gentler and rolling parts of the mountains, with ibex being adapted to inhabiting more rugged and steep cliffs. In short, her study was set up to determine whether terrain ruggedness was the primary factor allowing ibex and argali to coexist.

Overall, Chagsaa’s assumptions were correct. There was no statistically significant overlap between the distributions of ibex and argali in Tost. She found that the probability of detecting argali decreased as terrain ruggedness increased, indicating that the two ungulates kept to their preferred habitats: ibex along the steep cliffs and argali among the rolling hills. These findings suggest that there is probably little competition over food between these species in the South Gobi, as they graze on and use different parts of the desert landscape.

An additional variable that was taken into account was the effect that human activity had on the distribution of both ibex and argali. This was factored in by measuring road density and the presence of livestock, but no correlation was found between these two variables and the distribution of either ibex or argali. This might be unique for Tost which has a very low density of people, and the entire region has just about 90 herding families spread across the mountains and steppes. Most have only a single motorcycle per household, and there’s not much traffic to speak of. However, growing livestock populations can pose a threat to these species. Research on the diets of ibex and livestock by one of former researchers, the wonderful late Sumbee, had recorded a high potential for competition between ibex and livestock in Tost.

Chagsaa’s paper makes a valuable contribution to our understanding of how these amazing species of mountain ungulates, often referred to as mountain monarchs, use the habitat and coexist.

Odonjavkhlan, C., Alexsander, J.S., Mishra, C., Samelius, G., Sharma, K., Lkhagvajav, P. and Suryawanshi, K.R., 2021. Factors affecting the spatial distribution and co‐occurrence of two sympatric mountain ungulates in southern Mongolia. Journal of Zoology.

Thank you National Centre for Biological Sciences-Tata Institute of Fundamental Research and  Department of Atomic Energy, Columbus Zoo, David Shepherd Wildlife Foundation, Disney Conservation Fund, Phoenix Zoo, Mark and Vickie Fund of the Nysether Family, National Geographic Collaboration Grant, and the British Ecological Society for financial support and the Ministry for Environment and Tourism, Government of Mongolia, and the Mongolian Academy of Sciences for logistical and administrative support.

One Comment

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.