Effects of winter food availability on the abundance of Daurian pikas (Ochotona dauurica) in Inner Mongolian grasslands

Winter food is crucial for survival of animals in northern temperate regions where green vegetation is scarce or absent during the winters. The Daurian pika (Ochotona dauurica Pallas, 1776) is a steppe-dwelling, burrowing small mammal widely distributed in Inner Mongolian grasslands. Winters are severe in Inner Mongolian steppes with temperatures ranging from −40 to 5 °C. Pikas cache food plants in haypiles in late autumn. Forbs constituted over 90% of haypile biomass and were the main winter food of Daurian pikas. We conducted a haypile removal experiment during 1992 and 1993 to determine the ecological importance of haypiles. Pika densities in the spring were significantly lower on the removal plots than on the control plots. Therefore, haypiles as a food resource improve over-winter survival of Daurian pikas. Winter food availability may limit pika abundance in central Inner Mongolia.