Chipmunks and Chipmunk Ecology

chipmunkIAmong the most common kinds of wildlife observed by backpackers, campers, picknickers are smallish member of the squirrel family called chipmunks. These inquisitive and handsome animals often entertain family members during forays into natural areas. Chipmunks range throughout the U.S, and into Canada and Mexico. They have stripes (usually white) lengthwise along their brownish bodies, from their tails to their noses. They commonly sit upon their “haunches” (rear feet) with their somewhat bushy tails waving and jerking as they vocalize, or chirp.

Chipmunks are not true hibernators, but rather store up food in the summer times for wintertime use. They may sleep for a few days at a time while holed up in their dens, but intermittently wake up and feed upon their stored food. Dens may be located in rocky cliffs, underground in burrows, or other places offering relative security. They are quite adept at handling food with their forefeet as they sit. They are herbivores and mainly feed upon seeds, but also consume other plant parts.

The Eastern chipmunk (Tamias striatus) species has the largest areal presence in North America. It ranges from southern Canada through most of the southern U.S. states, and from the Mississippi River east. I count 39 additional chipmunk species* belonging to the Genus Tamias (formerly Eutamias) scattered mostly west of the Mississippi River, some extending well into Canada. There are a number of locations where ranges of more than one species overlap. Scientists call this “sympatry,” as opposed to “allopatry” (which means that ranges do not overlap).

Perhaps the chipmunk with the most extensive distribution west of the Mississippi into much of Canada is called the Least chipmunk. I have encountered this small member of the squirrel family in many unlikely habitats including in sagebrush stands, ditchbanks, roadsides or other disturbed habitats. One often hears a “chattering “ call as the chipmunk streaks away to safety, with its tail high in the air. Chipmunks are found in a variety of different habitats. They are seen on cliffs to pine forests to aspen stands to other natural habitats, even including disturbed habitat such as old strip mining areas, clearcut lumbering areas, abandoned roads, etc. The ways in which chipmunk species are differentiated from one another includes: differences in coloration and stripes, skull measurements and skull shape, bacular differences, etc.

I am particularly fond of chipmunks. I researched the ecology of the cliff chipmunk (Tamias dorsalis) as a thesis requirement many years ago in Logan Canyon, Utah. Unlike its sister species, cliff chipmunks have dark rather than white striping. In the canyon, cliffs contour the mountainsides high above the river in the bottom of the canyon. The cliff chipmunk is aptly named as it inhabits these perpendicular cliffs; some cliffs are up to a hundred or more of feet in vertical height. This chipmunk with its unique toes and toenails is able to navigate over the face of vertical rocks with impunity.

My study consisted of capturing the chipmunks in the springtime in live traps, marking them with dye, recording locations of capture. Then I traversed the mountainside rock slides below and above the cliffs to identify my previously marked animals. With binoculars, I kept track of their locations and the kinds of plants they were feeding upon. My objective was to determine the size of the area in which they travel about (called home range) over time. Also, I identified and compared the different kinds of plants they fed upon as the seasons progressed. It was also quite intriguing to observe these small animals carry seeds in their cheek pouches and then bury them in the dirt in small surface “caches.” Later in the fall, they would return to these caches and retrieve the seeds, carrying them to their individual den areas within the rocky cliffs for wintertime use.

I published a small 45 page soft bound booklet ** entitled, “How to Study Chipmunks – Ecology,“ that I am making available FREE for ordering; cost is only $2 for U.S. (residents) postage and handling. Send to “Chipmunk,” 11 East 500 North, Orem, UT   84057.

May you, as I have, find immense enjoyment from watching and interacting with these small and attractive wild cretures.

*Hall, E. R. 1981. Mammals of North America. John Wiley, New York.

**Hart, E.B,  1971. How to Study Ecology  —  Chipmunks