Building Better Bat Houses

Bat houses are great ways to provide homes for bats and enjoy the benefits of having bats in your backyard. Many people put up bat houses as a means to control mosquito populations around their homes. Others erect bat houses in gardens or amongst fields in order to control crop pests. Whatever the reason, many bat houses fail because of a few easily remedied problems. If you have ever thought about putting up a bat house in your yard consult the bulleted list below to make your bat house the best it can possibly be.

  • Paint it Black. Little brown bats (LBBs) are most likely to occupy bat houses and they like things hot. As hot as it gets in the summer in New York State, it is cool by LBB standards. LBBs have been found living in roosts with temperatures as high as 127 degrees. By painting your bat house black it will be able to absorb heat from the sun better than a lighter house would. Most bat houses sold in stores are a lovely unfinished wood and therefore unsuitable as bat houses in New York. Find one you like and simply paint it black.
  • Seal up cracks. Hold your bat house up to a light and look up from the bottom. Do you see light coming in anywhere around the top? If you do, it means air is also getting in. Air getting in the top of your bat house is going to lower the temperature. Get a tube of sealant and fill in the gaps until no light comes through the top.
  • Bigger is better. Bats like it hot. They also like to be with all of their friends. The larger your bat house is, the more bats that can move in. A larger house also means a greater temperature variant from top to bottom which equals an increased chance that your house will have the temperature the bats are looking for.
  • Trees are bad. It feels wrong to say it because I love trees but, as mounting sites for bat houses, trees are really bad. First, all of those branches and leaves are going to shade it from the sun no matter what color it is which will mean lower temperatures. Second, a tree is the easiest way for predators to reach the bats and eat them. Bat houses should be mounted on freestanding poles or buildings.
  • Sun is good. You’ve painted your house black. Now you need to put it somewhere where it will get the most sun exposure it can during the day. South or Southeast orientation is ideal when mounting bat houses.
  • Clearance. Regardless of the size of your bat house, when mounting it you should always make sure that there is at least 15 free feet of clearance from the bottom of the bat house to the ground. If there is a bush underneath, subtract the distance because it’s in the way. When bats leave for their evening flight they drop out of the house, spread their wings, and begin flight. The clearance provides enough space to get from the dropping to flying steps without injury or accident.
  • Protection. Bats come out of their houses at dusk before the sun is completely set. This can be a dangerous time with the air full of hungry hawks who haven’t turned in for the night and owls who are just waking. To keep your bats safe make sure the house is mounted within a quick distance of trees. Flying to the trees will help shield the bats from predators looking for an easy meal.
If you follow these guidelines you will give yourself the best chance of one day seeing the delightful sight below - a bat house that is full of hungry little bats.

I am always asked “is there a way to attract bats to a bat house.” The simplest answer is "no." The best way to get bats in your bat house is to make it the best bat house it can be. If you build it right, they will eventually come. Bat houses which are occupied the quickest are ones put up around homes and buildings that already have dedicated bat populations. The houses are built and left for the bats to discover. Eventually the bats are excluded from the buildings and often move into the bat houses that are near where they once lived.