Mild weather during mid-winter may entice them out of their dens for short periods of time. Chipmunks emerge to breed in late February and early March. During the spring season, the older females, yearlings and females born the previous summer season will breed. Older females may produce two litters per year. Most young are sexually mature at one year old.
Young chipmunks are blind and naked at birth.
They spend a month in the burrow system before leaving the den. Chipmunks rarely climb trees except to escape from predators, or to gather food. Travel of 75 yards or greater from the den would be considered exceptional. The outer fringes of individual home ranges often overlap with other chipmunks. Except during the breeding season, chipmunks are solitary, living in separate dens.