Ecosystem engineering influence of Mongolian marmots (Marmota sibirica) on small mammal communities in Mongolia

Abstract

Mongolian marmots (Marmota sibirica) live in colonies that consist of numerous burrows and are considered ecosystem engineers. Although once a common steppe species, marmots are now endangered due to overharvesting, which has led to concerns over the impacts of their loss on other species. The decline of marmots likely affected other species given their importance to the ecosystems they inhabit. To examine the role of marmots on small mammal, we established Sherman traps and drift fence arrays with associated pitfall and funnel traps on active marmot colonies, inactive colonies, and control sites in the forest-steppe and semi-desert zones of Mongolia. Overall, we identified 385 individuals representing 11 species of rodents and 1 species of bat in Ikh Nart and 149 individuals representing 2 species of rodents and 1 species of insectivore from Hustai. We found mixed results between diversity indices and abundance of small mammals on treatment and control sites, complicating the picture. During periods of greater precipitation and resulting higher vegetation cover, species abundance and the Shannon-Wiener, Simpson's, and evenness indices all changed significantly, suggesting that the effect of marmots on other species varies based on environmental conditions.