A Trio of Ground Squirrels Reside in Illinois

Casually driving down a country road, a tiny creature darted across in front of me. It ran into the grassy ditch, and I pulled over near the area where it had “disappeared.” Seconds later I saw a tiny head peering over the top of some short grass.

I knew immediately that I was looking at a thirteen-lined ground squirrel, one of the three species of ground squirrels present in Illinois. Some confusion exists with the identification of our ground squirrels, especially when it comes to the thirteen-lined ground squirrel and the eastern chipmunk. Another ground squirrel present in the Prairie State is the Franklin’s ground squirrel, which also can be misidentified.

Learning a little bit about each species, as well as looking at a few photographs, should end all doubt what you might be looking at.

Let’s start with the smallest and most common of these squirrels, the eastern chipmunk. Inhabiting much of the state, chipmunks prefer the habitat of hardwood forests, especially the outer edges. Rock piles and even outbuildings can harbor a few chipmunks. The eastern chipmunk has a small body, just 5 to 6 inches in length, with a 4-inch bushy tail that is held upright when running. Five white and dark stripe patterns begin at the shoulder and run the length of the body to the base of the tail. A blackish line runs through the eye with a tan stripe above and below each eye. Their tiny ears are slightly rounded.

The eastern chipmunk has an internal cheek pouch that is used in the collection of food. Foods vary, with nuts, berries, seeds, small insects and the occasional small mammal sought after. Much of their food is stored in a burrow chamber, typically in a chamber built for food storage only.

Mating occurs in February and March and then again in June and July, resulting in two litters a year. Three to five young are born in an underground chamber each birthing cycle. Baby chipmunks reach adult size in about three months.

Chipmunks do not hibernate in winter and on a warm winter day you may them out and about exploring. Learn more about eastern chipmunks at Chipmunk – Wildlife Illinois.

Thirteen-lined ground squirrels are slightly larger than a chipmunk and are found in the northern two-thirds of the state. Their body length is from 4 ½ to 6 ½ inches and their tail is up to 5 inches. Unlike the eastern chipmunk, a thirteen-lined ground squirrel holds its tail straight out when running. Light to dark brown in color with an off-white belly, the characteristic thirteen long stripes will include rows of spots on the top part of the squirrel’s body will have rows of spots. The striped do not continue onto the squirrel’s face.

Thirteen-lines prefer much different habitats than a chipmunk, seeking more open areas, such as prairies, golf courses, roadsides and even cemeteries. Needing to need to be able to see above the grasses when standing on their hind legs, thirteen-lined ground squirrels thrive in many of those areas as long as the grasses are not too tall.

Food sources are similar to chipmunks and include insects, seeds and plants, although they are known to take small birds and mice.

Thirteen-lined ground squirrels mate in April and May with young born in May and June. The single litter produced each year per year typically consists of six young. Young leave the nest after one month.

Another difference tween the thirteen-lined ground squirrel and the chipmunk is that thirteen-lined ground squirrels do hibernate, often beginning in November and perhaps hibernating up to 250 days of the year. Males hibernate first, followed several weeks later by females and young. The entrance to their nest chamber is often plugged to help keep them nice and toasty. Learn more about thirteen-lined ground squirrels at Ground Squirrels – Wildlife Illinois.

The largest—coming in at 9 to 10 inches in length with a tail up to 6 inches—of the three ground squirrels is the Franklin’s ground squirrel, which also is the rarest of the species, occurring in scattered locations across the northern two-thirds of the state. Franklin’s are uniform in color, lacking the spots or stripes of the other two species. Mostly gray in color with a light-brown tone, the belly of these squirrels is a lighter shade. They have a white eye-ring.

Franklin’s ground squirrels live in open prairie, open field edge, pasture and open woodland habitats. Like the thirteen-lined ground squirrel, they want to see over the top of the grasses when standing on their hind legs. Being much taller than a thirteen-lined obviously allows them to be in taller grasses, which in turn makes them harder to locate.

Their diet is similar to the thirteen-lined, with seeds, fruits, berries, plants, insects, and the occasional small mammal.

Franklin’s ground squirrels’ mate in May with seven to nine young born in June. Burrows are very well concealed and difficult to find. Learn more about Franklin’s grounds squirrels at Ground Squirrels – Wildlife Illinois.

Due to declining habitat, Franklin’s are an Illinois-threatened species. For this reason, few of us have never seen one. Toss in the fact that are known to spend 90 percent of their time underground hibernating (up to eight months of the year) and hiding from predators, finding a Franklin’s can be a difficult task.

There you have it. Just a few identification tips and telling these three ground squirrel species should never be a problem again.

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Kevin Wright is an award winning outdoor writer and wildlife photographer whose work has been published in a number of publications and websites throughout the country. He lives and works out of central Illinois.