Seasonal Changes in Body Mass and Energy Balance in Wild Small Mammals

Abstract

We review the seasonal patterns in body bass and energy balance in four wild, small mammals native to northern China. Specifically, we characterize the variations in mass, lipid content, hormone, and enzyme levels for two species inhabiting the Qinghai–Tibet plateau: plateau pikas (Ochotona curzoniae) and root voles (Microtus oeconomus), and two rodent species that inhabit the Inner Mongolian grassland: Brandt’s voles (Lasiopodomys brandtii) and Mongolian gerbils (Meriones unguiculatus). Generally pikas and gerbils maintained body mass and body fat content relatively stable despite seasonal fluctuations in food availability, while two vole species showed significant decreases in body mass and lipid stores in the winter. All species showed increases in their capacity for thermogenesis (adaptive thermogenesis) and subsequently increase total energy intake to attempt to meet increased metabolic demands during winter. We conclude that these wild small mammals have evolved different specific strategies to survive food limitation during the harsh winter.