Seasonal dietary patterns of Mongolian Marmots ( Marmota sibirica ) at a Mongolian steppe site

Despite the critical role of diet in mammalian ecology and conservation, the foraging ecology of the endangered Mongolian Marmot (Marmota sibirica) remains poorly documented. We conducted the first investigation of dietary composition and temporal foraging patterns in M. sibirica across the full active season in Mongolia, using microhistological analysis of fecal pellets collected weekly from March to September 2023. Marmots at this site consumed 45 plant species from 41 genera and 21 families, with dietary composition varying significantly across 6 temporal intervals. Forbs dominated marmot diets in all intervals (41% to 78%), while xerophytic and mesoxerophytic species collectively comprised 94% to 100% of intake, reflecting functional adaptation to arid steppe plant communities. Indicator species analysis identified 10 species with significant temporal associations, including early-spring specialists (Orostachys spinosa, Chamaerhodos erecta) and sustained mid-to-late season dominants (Haplophyllum dauricum, Thymus gobicus, Sibbaldianthe bifurca). There was also strong temporal turnover in dominant species, with O. spinosa dominating early spring (24.5%), Artemisia adamsii in mid-summer (24.7%), and H. dauricum across multiple intervals. Our findings establish M. sibirica at this site as a selective herbivore exhibiting strong temporal specificity on phenologically distinct taxa within xeric steppe plant communities. Because marmots function as ecosystem engineers providing critical habitat for diverse taxa, conservation and reintroduction programs should prioritize landscapes supporting diverse xerophytic plant communities with variable phenology across the active season.