Bat boxes

One method of creating bat roosting habitat or assisting with bat eviction is to build a bat box aka bat-house. But to be successful and help bats, it is important to do it right.

 

  1. First, consider if installing bat boxes is necessary – bat boxes provide alternate roosting habitat when bats are excluded from a building or natural habitat is lost. Read the current Best Practices for bat boxes in BC for more information. 
  2. Look at designs, decide which is suitable, and download plans. 
  3. Aim to provide a variety of microclimates – consider back-back maternity boxes, or multiple boxes that receive differing amounts of sunlight. 
  4. Carefully consider where and how to install. Many boxes don’t get installed, and of those that do, many don’t get occupied. 
  5. Register your bat box to contribute to Citizen Science
  6. Monitor annually by looking for guano, listening for bats, and joining the Annual Bat Count if your box is occupied
  7. Send in a guano sample for genetic testing to learn which species are in your bat box
  8. Don’t forget to maintain your box in fall or winter when bats are gone – make sure it is well attached, there are no leaks, and there are no wasp nests inside.

Some of the Regional Community Bat Programs have funding to help you acquire and place bat boxes. For instance The Kootenay Community Bat Project currently has a “Building Homes for Bats” program. Funded by the Public Conservaton Assistance Fund, the program allows the Kootenay Community Bat Project to reimburse the costs of your bat box materials, including wood, screen, screws, caulking and posts. Participants build and install at least two bat boxes to help us learn more about the best designs and placements for the Kootenays, and agree to monitor their bat boxes. Other regions may have similiar programs as funding allows. Contact your closest Regional Community Bat Program to find out.

Bat boxes can support hundreds of bats. At one site in the Kootenays, two “nursery” (multi-chamber) bat boxes that were installed back to back had over 800 bats emerge one night!

Frequently Asked Questions

The success of a bat box depends on the design and location of the bat-house, and whether or not there are bats in the neighbourhood looking for a roost site. When a bat box is installed in combination with exclusion of a colony from a building, it has a high chance of being successful. In other situations, it may take time before the bat box is used, particularly if there are many other roost sites in the area. If the location seems to be suitable based on the recommendations for installation, leave the bat box in place for at least two years before moving it to an alternate location.

Besides ensuring a good design and location for the bat box, there are few other attractants. Some people paint the bat house using a mixture of bat guano and water, but there is little evidence to support this technique. If possible, when providing a bat box in combination with exclusion from a building, try leaving the bat box inside the current roost site for several weeks before installing it so that it absorbs their smell.

The easiest way is to look for guano. If it is difficult to see, lay a light plastic or cotton sheet under the bat box for several days to catch any falling guano, or try making a guano catcher out of mesh. If bats are using the bat box as a day or maternity roost, you may be able to hear or see them during the day and they can usually be observed departing the roost around dusk. In good weather, watch the bat box for at least fifteen minutes before sunset and 30 minutes after for signs of use. If bats are using the bat box as a night roost between feeding bouts, they might be more difficult to detect. Look under the bat box for guano. Bats may also use the box for brief times at different seasons, such as early-spring or fall as they travel between main roost sites.  

Bats and birds use different habitats for food and shelter so they do not compete. Installing a bat box does not affect your ability to attract birds to your yard. Often, people install both swallow boxes and bat boxes to increase insect control.

Mounting a bat box