Ecosystem engineering by endangered Mongolian marmots supports darkling beetles

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. We examined the role of marmots and other landscape characteristics on the distribution of the darkling beetle, Blaps rugosa , a detritivore that serves important functions in steppe ecosystems. We surveyed 130 sites for B. rugosa in Hustai National Park, Mongolia, and used a model selection approach to evaluate the effect of marmot burrows on occupancy probability. We detected B. rugosa in 22% of surveys (87/390) and at 45% of sites. Our top model indicated that occupancy was strongly influenced by burrows. Estimated occupancy was 0.91 at burrow sites and 0.39 at non-burrow sites. Detection was a function of temperature and highest around 24.5 °C. Our results suggest that the loss of marmots will negatively affect the distribution of B. rugosa and the ecosystem processes they support. Our study provides one of the few examples of the role of marmots in influencing invertebrates, and supports the notion of marmots as a keystone species.