Usually it is active for two hours at a time. Then it retreats to its nest for a rest. The grassy nest is shaped like a ball about ten cm across. During winter, the red-backed vole builds its nest just underneath the snow. When it freezes in the fall with no snow cover and when it's wet in spring, many southern red-back voles die.
Scientists believe that more red-back voles die from the cold than are eaten by predators.
Still, the southern red-backed vole is one of the most successful mammals in North America because of its high rate of reproduction.