Over the last 3 years we have had a total of 5 bats in our house. Most recently yesterday morning. They seem to come into the house when the weather gets warm like it did on Monday. I have a feeling that they are roosting in our attic. I plan on doing an inspection/extraction when it gets a little warmer late Feb early March. We just finished a complete basement remodel which included sealing holes and gaps to the outside. Our fireplace is not used but I have them stuffed with rigid insulation and then fiberglass stuffed around the edges. My question is how are they getting in? Can they enter through water heater flue that has several turns? Can they enter the bathroom exhaust? I have heard that they can get between the walls and shimmy down. But the walls are insulated and then how do they get in the house from there? My final question is after I do an extraction if I put a bat house up am I just asking for more bats around the property or am I just giving them a better place to live?

Thanks

Bats hibernate for the winter. Given the number of bats you have had, I would say that they are hibernating in your attic. Some bat species are solitary, but others will roost together over the winter. Bats typically enter buildings through openings in the roof, eaves, dormers or gables, via the chimney, attic or roof vents, and holes or gaps in siding. They can get in via gaps of ¼ × 1 ½ inches or holes as small as 5/8 inches diameter. They wouldn't be coming in through the water heater flue, but the bathroom exhaust vent is a possibility. The bat (or bats) probably entered the house in late fall to find a place to hibernate. Many people never even know that bats have overwintered in their attics. The warm weather may have roused it early and it came down looking for a way out of the house. Since bats eat insects, and we won't have insects for several more months, coming out of hibernation now would not end happily for the bat. When dealing with bats, it is better to hire a licensed nuisance wildlife control operator to trap them, particularly if you are dealing with more than just one bat. The incidence is low, but bats can be carriers of rabies. Better safe than sorry. Especially if there are children or pets in the house. Bat houses are great as summer-time roosts. But they don't provide the level of protection needed against Illinois winters to keep the bats alive over the winter. That's why caves and dead trees are so important as habitat. And the lack of these natural habitats is what drives bats into our attics. Let me know if you have more questions.