There are three species of small ground squirrels in Illinois, the Eastern chipmunk, the thirteen-lined and the Franklin’s. Actually, a fourth member of the ground squirrel group in Illinois should be noted and that is the groundhog, also known as a woodchuck.
The Eastern chipmunk is the smallest ground squirrel in Illinois with a body length of up to 7 inches, not including their furry tail that is about 4 inches in length. Chipmunks have a reddish-brown coat with black and white stripes on their back and the sides of their face, and a white stripe above each eye.
They are most often seen in or along wooded or thick brushy areas, where they have their borrows nearby. They can construct their borrows beneath fallen trees or even within the roots of living trees. They also use rocky environments where they can easily create borrows beneath or between the rocks.
A little larger than the Eastern chipmunk is the thirteen-lined ground squirrel, which is 13 inches in length, including a small 3-inch tail. The thirteen-lined ground squirrel is a prairie or grassland animal that actually expanded its range after the Europeans arrived and began clearing timber and creating pasture lands.
Here in Northeastern Illinois, you are most likely to get a glimpse of this little ground squirrel on a sunny day, standing up straight on its back legs near its borrow keeping a wary eye as you approach along a rural, less-traveled road. Look for those large, dark eyes and those many stripes, 13 to be exact, that alternate in different shades of browns, yellows, blacks and have light spots in the darker stripes.
And larger yet, at about 16 inches, including the tail, is the Franklin’s ground squirrel. Sightings are rare and highly localized in the northern two thirds of Illinois for this ground squirrel that sort of resembles a cross between a tree squirrel and tiny marmot.
The habitat of tall grasses that the Franklin’s ground squirrel requires makes actually seeing one very difficult. Researchers have used trained dogs in some areas to help locate ground squirrel activity in suitable tall grass habitat of the Franklin’s, a technique mentioned in an article of Outdoor Illinois, Duggan et al.(2009) “Finding Franklin’s.”
The Franklin’s ground squirrel in Illinois has a status of “Uncommon, listed as state-threatened in 2014,” and they are a protected species under the Endangered Species Act according the Illinois Department of Natural Resources.