Pikas (Ochotona spp.) are burrowing herbivorous mammals believed to play a keystone role in determining the biodiversity of steppe ecosystems. Impacts of domestic livestock grazing on the distribution and abundance of the Daurian pika Ochotona daurica were investigated in eastern Mongolia where the species is widespread and abundant. Effects of pikas on plant species richness and vegetation coverage were examined at different distances from burrow systems. Daurian pikas were nearly absent from severely grazed study sites, and incidence of the species increased with decreasing grazing intensity. The number of occupied burrow systems and usage of burrows was higher in sites with lower grazing pressure. Plant species richness and ground cover was higher at 3–12 m from the burrow systems than directly over burrows, suggesting that the effect of Daurian pikas is limited to the burrow system. Contradictory to previous studies on grassland pikas, this study indicates that Daurian pikas suffer from overgrazing and that their impact on grassland is only light.
