Nearly 5,000 Illinois records make the eastern chipmunk one of the best-documented mammals in the state. Chain O’ Lakes State Park and Starved Rock State Park hold the largest named clusters, and the map runs from the wooded ravines of Forest Glen Preserve and Shawnee National Forest up through the Chicago-region counties, where Cook, DuPage, and Lake lead the record.
A burrower that lives on its pantry
The chipmunk spends much of its life underground, in a burrow system with separate chambers for nesting and for storing food. Through summer and fall it stuffs acorns, seeds, and berries into its cheek pouches and hauls them below, building the caches it will live on through winter. That need for both cover and mast keeps it tied to woodland edges, brushy fencerows, and rocky ravines rather than open prairie.
Underground, but not truly asleep
The Illinois calendar for the chipmunk nearly empties from December through February, then surges in March. Chipmunks are not true hibernators. They retreat to the burrow and slip into repeated bouts of torpor, waking every few days to eat from their stored food and surfacing on mild winter days. By April and May, breeding activity and this year’s young keep them above ground and in plain sight.
Status in Illinois
NatureServe ranks the eastern chipmunk S5, Secure, in Illinois, and the species is native across the state. USGS NAS does not list it as nonindigenous here.
