Actually, they are in a house designed just for them. Several years ago, I became interested in bats. Bat Conservation International is a great source of information on bats. They also have information on building and attracting bats. I ordered a bathouse kit to assemble. We erected it in June. The next January,we had 7 bats in it. Now we have around 200! I am working on a second house to accomodate them. They eat more nightflying insects such as mosquitoes, than Purple Martins. My bathouse is mounted at the edge of my garden. Each spring, I spread the guano around the garden and till it into the soil.
A few weeks ago, we went on a trip to Fredericksburg, Texas. I was thrilled to go to the "Old Railroad Tunnel" which is now a home to Mexican Freetail bats. Watching them exit was a thrill. They looked like a dark cloud. They even show up on weather radar until they disperse enough.
Scroll down to see a photo of one of the newborn bats. I think it looks like a gargoyle!