One major reason for the decline of bats is the loss of habitat. One option to counteract this problem is install a bat house.
A bat house is a shelter where bats can roost during the day. Setting up bat house can help facilitate the conservation of bat populations. Furthermore, if you want the bats to leave your house, but still keep them in the surrounding area, setting up bat houses can help keep bats in the area after removing them from your buildings.
In order to maximize the success of bat houses, here are some guidelines:
Set up bat houses at the beginning of April before the birthing season or at the end of the summer, in preparation for the following year
Bats seek out heat. This is important to think about when deciding on the location of a bat houses
Ensure that your bat house faces South or East in such a way that it receives as much sunlight as possible, in order to maintain an elevated temperature inside (ideally, 8 to 10 hours of sunlight a day). The best option is therefore to put the bat house where there is little to no shade
In southern Canada, when daytime temperatures reach extreme levels, there is a risk of the bats within the bat houses overheating. Ideally, two bat houses with different exposures should be installed, which will allow the bats to choose the one with the optimal temperature for their needs and move between the houses if necessary
Install the bat house at least 3 meters above the ground on a building or pole to avoid predators. Bat houses set up in trees are more difficult for the bats to find. Trees can also create shade, reduce sunlight, and the branches may hinder the bats’ flight. As a result, bat houses should preferentially be installed on building in order to provide a more stable environment for the bats
Make horizontal saw marks at 2 cm intervals on the bat house’s inner boards so that the bats can hang on to them more easily
Make sure that the approach zone is unobstructed in order to facilitate the bats’ movements in and out of the bat house (remove any obstacles or branches)
Place at least two bat houses in the same place, which will allow the bats to choose the one with the optimum temperature for their needs, and move between roosts if necessary
Do not place bat houses near bright, artificial light sources, such as street lamps
Caulk your bat house well in order to stop light and water from entering
Paint the outside of the bat house black or dark brown in order to increase the internal temperature. Use water-based paint, not oil-based paint and apply three coats. You can also cover the roof with asphalt shingles
Do not use treated wood because it could contain chemical products that are toxic for bats
Preferably, use galvanized screws instead of nails for the exterior
If your bat house has not been used after two years, move it somewhere else
When the bat house is in use, avoid disrupting its occupants
When the bat house is occupied, you can count the individuals. This will give you an idea of the size of the colony inside the bat house
Chances of success
The occupancy rate of bat houses is variable. Research shows that it depends more on the location than the design of the bat house. Moreover, larger bat houses are preferred by some bat researchers because they provide better heat retention and they are less likely to cause the bats to overheat. If you have excluded bats from their usual roost, you can increase the chances of them occupying a bat house by putting it as close as possible to the entrance of their previous roost.
Bat house maintenance
Bat house maintenance is very simple and should be done in spring before the birthing season or in fall, in preparation for the following. Bats usually leave reproduction sites for their hibernation site at the end of summer and come back in spring. Before cleaning, make sure you are well prepared and that no bat uses the house. Excluding bats could result in serious consequences for them.
For your security, wear a N100 mask, gloves, and protective glasses. Look for the presence of spider webs, wasp nests, guano, or any other undesirable elements. Remove them and clean the bat house with a brush, hot water, and non-toxic soap. If there is mold on or inside the bat house, it must be removed with a metallic brush and a mix of hot water (90 %) and bleach (10 %). After cleaning, rinse the bat house with abundant water and let it dry. Check the house’s hardware and tighten or replace any loose screws. If the damage is noticed, it is suggested to caulk the holes and cracks using silicone in order to a stoplight, wind, and water from entering. Finally, if needed, you can repaint the bat box with black or dark water-based paint. A house that suits bat requirements has a higher colonization probability. If your bat house has not been used for a few years, move it somewhere else where there is a better sunlight exposition. When cleaning is done, disinfect all your equipment using a mix of hot water (90 %) and bleach (10 %) and wash your hands properly with hot water and soap.
If you want to set up bat houses, you can buy them from certain retailers or even build them yourself (Bathouse List). If you acquire them from a retailer, make sure that they are in compliance with the criteria listed above. You can find local retailers by looking on the internet.
If you are a Canadian bat house retailer and would like to be added to the list, please send your contact information to us.
Should you be concerned with rabies when drawing bats into a bat house?
Like most mammals, bats can contract rabies, but the very wide-spread rumour that most of them are rabid, i.e. carry rabies, is false. Generally, a rabies-infected bat can no longer move about after 48 hours and dies within four or five days. However, it is still important to be careful around bats just in case. Never touch a bat without having taken all of the appropriate precautions.