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Mammals

Tree Squirrels

Photo: Sheila Newenham
An Eastern gray squirrel runs across a gray, concrete road with a peanut in its mouth.

Did You Know?

  • Tree squirrels are rodents and are in the same order (Rodentia) as the ground squirrels, mice, rats, voles, muskrat, beaver, plains pocket gopher, and southern bog lemming.

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Positive Benefits

Squirrels are a source of food for owls, foxes, and other predators. They are also important to the ecosystem because they distribute nuts and acorns across the landscape.

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Description & Identification

Four species of tree squirrel occur in Illinois. All are small mammals characterized by a long and bushy tail, prominent ears, and long hind feet. None of the tree squirrels hibernate, but they do have periods of reduced activity during severe cold weather.

Fox squirrel (Sciurus niger): The fox squirrel is the largest tree squirrel in Illinois, weighing 1¾ to 2 pounds and having a length of 19½ to 22 inches. The fur is a mix of rusty-yellow with black giving an overall reddish cast. The fur on the ears, belly, and edge of the tail is lighter.

Photo: Adele Hodde, IDNR
Fox squirrel sitting in a tree. Fox squirrels are larger than the other tree squirrels with large, bushy tails, grizzled gray and brown fur and rusty colored fur on their underside.
A fox squirrel sitting in a tree.

Eastern gray squirrel (Sciurus carolinensis): The gray squirrel typically weighs 1¼ pound and has a length of 17¼ to 18¼ inches. The fur is gray on the back and white to light gray on the belly. Melanistic (black), leucistic (white), and albinistic (albino) variants occur in Illinois. For example, squirrels with black fur can be found in Fisher and in Gibson City, and squirrels with white fur are common in Olney and in northeastern Illinois.

Photo: Jim McCormac
Eastern gray squirrel sitting on a tree branch.
An Eastern gray squirrel.
Photo: crazyjoepaul, CC ASA 4.0 International
Melanistic phase of the Eastern gray squirrel.
The melanistic phase of the Eastern gray squirrel.
Photo: Scott Shetler
A white Eastern gray squirrels in Olney, Illinois.
A white Eastern gray squirrel in Olney, Illinois.

 

Red squirrel (Tamiassciurus hudsonicus): The red squirrel is smaller than the fox or gray squirrel, weighing approximately pound and has a length of 11½ to 13½ inches. The fur is reddish gray on the back and whitish on the belly. Ear tufts are present in winter. Red squirrels can be found in the northeastern counties of Illinois.

 

Southern flying squirrel (Glaucomys volans): The southern flying squirrel is the smallest tree squirrel in Illinois; weighing approximately 2 ounces, and has a length of 8⅝ to 9¾ inches. Their fur is glossy gray to cinnamon brown on the back and white on the belly. The eyes are large, and the tail is flattened. This squirrel appears larger than it is because of the folds of skin on either side of the body that extend from the wrist to the ankle. This feature gives the squirrel its gliding capability.

A southern flying squirrel.

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Size Comparison

 

Illustrator: Lynn Smith
Man and tree squirrel illustration
Size comparison of a six-foot-tall man and the four tree squirrels found in Illinois.

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Distribution & Abundance

Photo: Sheila Newenham
Gray squirrel sitting in a bird feeder.
An Eastern gray squirrel sits in a bird feeder.

Fox squirrels are common throughout Illinois, even in urban areas. Loss of mature, wooded habitat has decreased the population of gray squirrels in Illinois, although they remain common throughout the state and are locally abundant in urban areas. Red squirrels are found only in the northeastern part of the state, particularly along the Kankakee and Iroquois Rivers. Southern flying squirrels are found throughout Illinois but are most abundant in southern Illinois.

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Behavior & Ecological Role

Fox, gray, and red squirrels are diurnal, meaning that they are active during the day. Southern flying squirrels are nocturnal and are active at night. All tree squirrels are active year-round, although they will take shelter in their nests during extreme cold weather. Fox and red squirrels spend more time on the ground than gray squirrels. Due to the extra skin on their sides, southern flying squirrels are able to glide from tree to tree, but they are not able to fly as their name suggests. All tree squirrels are solitary; however, since they are not territorial many may be seen in close proximity to each other, particularly if there is a good supply of food. The young often stay near the female until the next litter is born. Nests in tree cavities are preferred, but when cavities are not available squirrels will build nests of leaves in trees.

Photo: Jared Duquette
Tree squirrels build nests out of sticks and leaves near the tops of trees. They make multiple nests so they can quickly move if a nest is damaged by storms or attacked by predators.
Tree squirrels build nests out of sticks and leaves near the tops of trees. They make multiple nests so they can move quickly if a nest is damaged by storms or attacked by predators.

Tree squirrels play an important role in forest regeneration. Squirrels bury tree seeds and nuts as a way to cache food for use later in the season. However, they do not return for all of the seeds and nuts that they bury, and some of these later sprout and grow into trees. Squirrels are also an important part of the food web, being preyed upon by several species of avian and mammalian predators.

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Diseases & Public Health

Tree squirrels in Illinois are not considered to be a public health concern. They can be carriers of various parasites, but none have serious public health implications.

Photo: Eileen Beatrice
It is not uncommon to see squirrels with patches of fur missing.

It is not uncommon to see squirrels with patches of fur missing. Hair loss in squirrels is often caused by mange or fungal disease. Otherwise healthy squirrels can recover from mange or fungal infections.

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Reproduction & Longevity

Each squirrel species has two breeding seasons, one in winter (January and February) and the other in late spring (March) or early summer (July). Female fox and gray squirrels that are at least two years old have two litters per year; younger females have only one litter per year. The average litter size is two to four young. Southern flying squirrels may have litters of up to seven young. Young squirrels are weaned around eight weeks of age.

Like most rodents, tree squirrels have a relatively short lifespan. Most live only a year or two. Hawks, owls, foxes, and coyotes all depend on squirrels as a food source.

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Damage Prevention & Control Measures

Squirrels are excellent climbers and jumpers. They are well known as unwelcome guests at bird feeders. Besides consuming seed, they may damage bird feeders by chewing on them. They may also occasionally damage lawns when they dig holes to cache food. They will sometimes damage garden plants, particularly corn. While these behaviors are inconvenient, they can usually be handled by modifying the habitat or excluding the squirrels.

In urban areas, squirrels may cause substantial property damage when they chew through siding or enlarge openings to gain access to attics. Once inside a building they may do further damage if they chew on insulation or electric wiring. Squirrels may also cause power outages when they short out transformers.

It will likely be necessary to use several techniques to control property damage by squirrels. Exclusion is typically the most effective method.

Habitat Modification

Since squirrels can jump up to 10 feet, trim tree branches back at least that distance from buildings to prevent squirrels from accessing the building.

If squirrels are a problem around bird feeders, provide corn for the squirrels away from the bird feeders, or use bird feeders with squirrel deterrents such as baffles.

Exclusion

To prevent squirrels from climbing on isolated trees or power poles, attach a two-foot-wide metal collar around the tree or the pole six feet off the ground. On trees, attach the metal collar with wires held together with springs to allow for growth.

Regularly check buildings on the property for places that need repair. Repair holes and openings as soon as they are noticed, making sure not to trap animals inside. If a hole is found, loosely stuff newspaper in the opening. If the paper has not been moved after two or three days, it is safe to proceed with repairs.

Repellents

There are a couple of taste repellents that can be used to discourage squirrels. Capsaicin is a readily available repellent made from red peppers. It can be used to treat birdseed to discourage squirrels from raiding bird feeders. Capsaicin does not affect birds and is safe to mix with birdseed. Ro-pel is another taste repellent that can be effective at discouraging squirrels. It may be applied to seeds, bulbs, trees, shrubs, fences, siding, and outdoor furniture.

Frightening Devices

Placing a light (mechanics or strobe) or radio in the attic may temporarily discourage squirrels from using the area, but once they become accustomed to the device it will no longer be effective.

Removal

If you need assistance with removing a squirrel from a building, you can call a nuisance wildlife control operator, who will trap the squirrel for a fee.

If you are going to trap a squirrel (even if it will be released onto the same property), you will need a PERMIT from an Illinois Department of Natural Resources district wildlife biologist. The biologist can provide information on options for resolving problems, including issuance of a nuisance animal removal permit.

If squirrels are inside the building and will not leave, set live traps to capture them for release outside, or install a one-way door over the opening so that animals can leave but not enter the building. An 18-inch-long section of 4-inch-diameter plastic pipe pointed downward at a 45-degree angle can be placed in the access hole instead of a one-way door. If the opening is large, heavy wire mesh (½ -inch squares) can be placed over the opening. Once all animals are out of the building, repair the opening.

Click HERE for more information about hunting Game animals. Current hunting and trapping seasons can be found in the Illinois Digest of Hunting and Trapping Regulations or in the Legal Status section below.

 

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