Bats are found throughout DuPage County in forest preserves, parks and backyards. They are unique because they are the only mammals in the world that can fly. They navigate in part by emitting high-frequency sounds, which are reflected back when they hit an object. By detecting these reflected echoes with their funnel-shaped ears, bats are able to locate tiny insects and larger objects in complete darkness. Their ability to find food in the dark has led to the myth that bats are blind, but on the contrary, they have excellent eyesight.

The six species that are likely to reside in DuPage County — the little brown bat, big brown bat, red bat, hoary bat, silver-haired bat and northern long-eared bat — are all insectivores. While they have the reputation of eating thousands of mosquitoes in one night, the truth is that mosquitoes make up only a small part of a bat’s diet. The animal is more likely to feast on moths, June bugs and other larger insects, which are much easier to catch.

Bats like to roost in secluded, warm locations, such as under loose tree bark or in quiet attics or neglected buildings. Young are born between May and June. Females usually have one young at a time but occasionally have two. They often roost together and form maternity colonies, where young bats are born and raised. When the mothers leave the roost at night to forage, their young are left behind until they are old enough to forage on their own, after about three weeks.

As winter approaches and the insect supply diminishes, bats will migrate to caves, where they enter a state of “torpor,” or decreased activity. Their heart rates can drop from over a thousand beats per minute to one beat every four or five seconds, which allows them to survive for months on very little fat.

A Bat in the House

An individual bat that has entered a house has done so by accident. If you know its location, close interior doors to limit access inside the house. In the evening, open a window or exterior door in the room with the bat. Left alone, it will find the opening and leave. 

Never touch a bat. In DuPage County, law enforcement and animal-control officers are responsible for removing bats from living quarters.

Preventing Problems

Bats can enter buildings through holes smaller than an inch in diameter. The best way to keep bats out of a home is to eliminate possible points of entry before the animals can move in.

Seal exterior openings larger than half an inch with caulk, expandable foam, plywood, mortar, metal flashing, steel wool or quarter-inch mesh screen or netting. 

Make sure all doors, windows and screens close properly.

Turn on a bright light in the attic at night to look for light escaping through the openings on the building’s exterior.

Repair broken, weak or rotted areas on your roof, soffit and fascia. 

Install and maintain chimney caps before animals move into your chimney.

Use welded wire to prevent animals from accessing openings under decks, elevated sheds, concrete slabs and porches. 

Public Health Concerns

Histoplasmosis is a fungus associated with accumulated bat and bird droppings. People who inhale it can be at risk of infection or serious disease. Cleaning up accumulated droppings generally involves wearing personal protective equipment; the removal of large amounts should be left to experienced professionals.

While rabies is rare in Illinois, bats and skunks are the two wild animals most likely to be infected with the virus, although less than one-half of 1 percent of all bats carry it. Bats carry the virus in their saliva, which also coats their bodies during grooming. A person contracts rabies through a bite or a scratch from an infected animal or when infected saliva comes in contact with the eyes, nose or mouth or an open wound.

Without treatment, rabies is fatal. Any bat suspected of having physical contact with a person should be captured and submitted to the DuPage County Health Department for testing. Health professionals may deem postexposure treatment necessary if a bat cannot be tested. (Current vaccines are relatively painless and are given in the arm, like a flu or tetanus shot.)

What Not To Do

  • Never touch a bat. In DuPage County, law enforcement and animal-control officers are responsible for removing bats from living quarters.
  • Trapping and removing a bat is not always a solution to the problem. Removing the animal is illegal without the proper permits and only creates an open space for another animal. A trapped adult may also leave young behind to die of starvation in an inaccessible area. Focus on removing the attraction, not the animal.
  • Never move young from the nesting site. 
  • Do not use poisons. They are inhumane, may be illegal, and can result in secondary poisoning of raptors, wild scavengers and neighborhood pets.
  • It is illegal to keep wild animals, even for a short time. They have specialized nutritional, housing and handling needs that you are unlikely to be able to provide. Inexperienced individuals who attempt to raise or treat them inevitably produce unhealthy, tame animals that cannot survive in their natural habitats.

Willowbrook Wildlife Center

If you come across a wild animal and are concerned, leave it alone. Call Willowbrook Wildlife Center for advice at (630) 942-6200. The center is located at 525 S. Park Blvd. in Glen Ellyn and is open 9 a.m. to 5 p.m. every day except select holidays. Recorded messages provide general information for callers when the center is closed.

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©2016 Forest Preserve District of DuPage County