The key moment of their collective lives as a species comes in late February or March, when they emerge from their burrows to mate and produce three to five babies. A second litter may be produced again in mid-summer.
The remainder of this squirrel’s life is devoted to stocking up their underground storage bins for the winter. This stocking up is conducted with such vengeance that from spring until late fall any chipmunk observation you make will likely be of one scurrying from or back to its burrow along well-worn pathways in search of additional provender.
Dare to interrupt this ritual and you’ll be duly scolded — if not harangued — in no uncertain terms. The message is clear: “Watch out! ... Stand back! ... I’m busy!”
Even though their food bins are often overflowing by late summer, the coming of the first frosts stimulates something in the little critter’s psyche that activates an even more frenzied last minute flurry of collecting.
Nineteenth century naturalist and writer John Burroughs called such periods “the nutty days”: a time when “the woods will often be pervaded by an undertone of sound produced by their multitudinous clucking. It is one of the characteristic sounds of fall.”
Before you can stock up, you’ve got to have storage areas and the chipmunk is a master builder of such places. Its methods of designing and filling them would make proud any self-reliant busybody with stuffed freezers, overflowing shelves of canned goods, smokehouses filled to the rafters, and bulging vegetable bins.
Chipmunks can be thought of as “communal hermits.” That is, although 10 or more individuals might live in a single acre of prime habitat (two or three per acre is more usual), they rarely den together. Instead, each chipmunk constructs his or her own abode (with adjacent food and water rites) that it fiercely defends.
After locating soil that is easily dug, it digs straight down for half a foot, then continues at a 45-degree angle for about two feet to a depth of almost a yard below ground surface. This penetrating shaft is two inches in diameter. The sleeping den within the burrow consists of a room about 20 inches wide and 10 inches deep in which the animal constructs a nest of dried leaves and grass.
Under this nest, food is stored so as to be handy for a late winter snack. But this is just the tip of the iceberg. Special rooms off the main passage hold reserve stores that any self-respecting chipmunk fills to the brim. And just for good measure, auxiliary stores away from the main burrow called “scatterhordes” are often maintained as well.
When not gathering their own supplies, chipmunks add a little spice to their lives by constantly raiding one another’s food stores. A constant exchange of black market items is always being circulated from one burrow to another. Such thievery is so common in chipmunk circles that some observers feel certain that the “scatterhoards” are constructed primarily for stolen goods.
What does a chipmunk store? Most anything that’ll keep. But they’re noted for being particular. Any old nut won’t do. It has to be prime. In Russia — where their dens are systematically raided by humans — so-called “chipmunk nuts” fetch a higher price than those gathered otherwise.
Curious to discover just how much food a chipmunk would store if given free rein, John Burroughs made five quarts of hickory nuts, two quarts of chestnuts, and enough shelled corn to make a bushel available to a single individual. Meeting the challenge, the animal hauled it all away in loaded pouches before the naturalist decided to call it quits.
Little wonder, then, that a long-lived chipmunk in the wild of four or five years age (they will live to be 12 in captivity) can eventually have a burrow of up to 30 feet in length with four or five off-shoot tunnels and escape exits, along with six or more storage rooms, in addition to the main den and various “scatterhoards.”
Unlike their cousins the woodchucks, chipmunks are not true hibernators. Once underground with entrance holes plugged tight, they curl up in balls and go into periods of deep torpor lasting from a few days to a week. Periodically, however, they awaken to defecate and choose from among the vast array of stored items for nourishment. This underground castle is always kept spic-and-span as the animal has also prepared special rooms for waste disposal.
If a warm period occurs during the long winter months, a chipmunk will open an entrance hole and emerge to check out the scene in the above ground world. Come early spring they will emerge to seek a mate and initiate their food hoarding obsessions all over again.