Food foraging and other above-ground activities are carried on during daylight. Chipmunks are most active in early morning and late afternoon. A chipmunk's activities and individual territory center on its burrow, which may be simple or intricate. The entrance, about two inches wide, is usually hidden under a rock, tree stump, log, or at the base of a fencepost or stone wall. Burrows plunge straight down for several inches, then level off and extend 30 feet or more, sometimes branching into offshoot tunnels with separate entries.
Chipmunks dig their burrows, pushing or carrying excavated dirt away from the entrance.
Somewhere in the system is a foot-square nest chamber lined with crumbled dry leaves and grass. A chipmunk stashes nuts, seeds, corn, etc. In autumn, chipmunks gather winter food, storing it in their burrows or in above-ground caches in their home territories. They do not enter winter with a thick layer of body fat, as do true hibernators. In late October or early November, they go underground to live on stored food until spring.