Bats are nocturnal animals that seek shelter during the daytime. Suburban and urban development have decreased the number of natural places that bats can roost. The number of bat houses you choose to put up depends on how many bats you want to attract, how many different species you want to shelter and how plentiful the resources are in your area. Put up bat houses in groups of three to maximize the chances of getting occupants.

The Right Bat House

Most bats are insectivores--they eat lots of insects, including moths and mosquitoes. Some species can eat up to 1000 mosquitoes per hour. Other bat species are important for pollinating flowering plants. Different species of bats have different shelter preferences. Contact your local university or Department of Fish and Game to find out what species of bats are native to your area. Then choose a bat house that is appropriate for those species. Studies have shown that non-aromatic woods are best. They should be carefully caulked and sealed to prevent drafts, yet ventilated to prevent overheating in the sun. Some bats prefer horizontal roosting areas. Bat houses can have landing pads, attics, and more than one room inside.

Groups of Three

Bats love company. Some bat houses can shelter 50 bats or more. The Organization for Bat Conservation states that 25 percent of successfully occupied bat houses were in close proximity to other bat houses. Bat houses constructed in groups of three, a few feet apart and with different exposures to the sun, allow bat families to move their young to the most comfortable shelter depending on the temperature and weather. Bat houses can likewise be placed on different sides of trees in threes with the same purpose in mind. Groups of three bat houses seem to yield the highest occupation rates.

Expert Insight

After your bat house is occupied, you can increase the chances of having other bat houses being occupied by placing bat guano (droppings) in the new houses. Bats are sensitive to smell and the guano seems to make them feel more at home. Likewise, aromatic wood or new wood houses are less likely to be occupied until they weather a season or two and lose their strong scent.

Source:

Bats Eat Mosquitoes

Bat Houses

Tuttle, Merline D, Hensley, Donna L. "The Bat House Builder's Handbook," 2003