Strategies for Successful Bat Houses

Bats are a very important creature in controlling of various insects. While their reputation for controlling mosquitoes is probably overrated, bats tend to fly too high to catch many mosquitoes, they do eat them. I want you to know how to help make your property hospitable to bats. The reason why we need more people to make homes for bats is because our increased urbanization has removed the hollow trees they need to raise young. It is this lack of traditional denning sites that has forced the small and big brown bats to adapt to roosting in homes. While I don’t advocate your permitting bats to live in your home, I do think that people concerned about ecology should consider installing a bat house.

Before we begin, I need to give you a few warnings. First, bats are very choosy about where they live. Even if you follow all the recommendations given in this article, don’t be surprised if your bat house doesn’t attract any bats. I can assure you however, that following these recommendations will certainly increase the chances of attracting a bat colony. Second, just because a colony chooses to live in your bat house doesn’t mean that your backyard will be insect free. Bats will only help minimize the volume of insects. They will not eradicate them. On the plus side however, they will do all their work free of charge and without potentially dangerous chemicals.

  The information that follows has been gleaned from two very valuable publications. If you desire more detailed information on the subject of bats and bat houses, I strongly encourage you to scroll to the bottom and look at the bat house resources section of this page.

Unfortunately, most bat houses sold in hardware stores are just not the best models. They tend to built more for their attractiveness to our likes rather than those of the bat. Here is a diagram for building a beginners bat house. Although, larger bat houses are more attractive to bats and thus have a higher occupancy percentage, it is better to start with something you may find easy to create.

The designs are fairly simple. Just be sure to use rough hewn wood. The bats need something they can cling too. Also paint the top half of the box black so that it will get warmer in the summer sun. the reason you don't want to paint the whole box black is because the bats need temperature variants in the box so they can climb up and down depending on their temperature preferences. Picture at left is a single room bat house and the one on the right is a multi room bat house. Please note their relative size. These houses are large. The multi room is about three times as wide as the single room. Both are the same height.

Bats and Insects

I would caution you on the extent of mosquito control that bats will provide. Remember, that if a bat is too sucessful at killing mosquitoes he will effectively eat himself out of existence. Trophic levels in biology tell us that this doesn't happen. So if you are looking for mosquito free or even rare mosquito living, then bats won't do it for you. Will they help? Sure, but so doesn't it help when you slap a mosquito that is biting you. At best the help is marginal.

Nevertheless, I hope you put up a house.

Once you have built your bat house, you must properly install and maintain that house. Here a few principles to guide your actions.

First, place the bat house where it can receive a great deal of sunlight. While bats don’t like sunlight they do need warmth in order to raise their young. Studies have shown that nursery bat colonies need ambient temperatures of 80-90 degrees Fahrenheit. Bats are very fussy about this so be sure to do what is in your power to allow the house to retain heat. Placing the house on a free standing pole will provide the house with the most opportunity to receive solar radiation. If this is not practical, place the house so that it faces a more generally southern direction. This point cannot be overemphasized so be sure your bat house will get enough heat. Another way to encourage heat retention is to paint the house black.

Second, place your bat house at least 15-20 feet off the ground. They can be placed on the side of your house, a tree or mounted a free standing pole. Studies have shown though that bat house occupation is more likely for houses placed on poles and the sides of buildings than on trees. Be sure that the house is properly anchored to prevent it from falling down in high winds.

Third, place the bat house where the bats can fly to it freely without obstruction. Obstructions will make their flying difficult and will block the sun’s rays as well. The greatest percentage of occupied houses had flight obstructions no closer than 20 feet away.

Fourth, bats like to live in areas near standing water. Typical roosts exist within 1/2 mile of water.

Fifth, be patient. Leave your bat house in place for at least two years. If it isn’t occupied in that amount of time then move it to another suitable location.

Sixth, some people believe that bats will more likely to enter a bat house if fresh bat guano on the inside of the house. (Warning, feces can carry diseases that are dangerous to humans. Use appropriate safety equipment before using bat guano. Diseases can be inhaled, ingested and possibly absorbed). There is now an easier solution, Bat Call (Bat Paste Gland Lure). I can't guarantee this product works every time. I would love to get more feed back on the product. However, people with more experience with bats than I, suggest that bats are more attracted to bat houses that smell like bats have already lived there. With that caveat, I suggest giving the product a try. As always, I would love to hear about any success stories or failures.

 

Other Bat House Suggestions

1. If bees take up residence in the house, then remove them with the water from a garden hose. DO NOT USE INSECTICIDES because they may seep into the wood and injure any bats that may roost there.

2. If bat feces begins to reach a noticeable amount, treat it as you would any fecal material, taking special care not to inhale the dust. If it is too dry, wet down the feces (also called guano), this will keep the dust down, wear a mask able to filter particles as small as 5 microns (HEPA Filter you will need instructions on proper use), and bury it.

3. Using a flashlight check your bat house 1-2 times a month until it becomes occupied. Once the house is occupied, watch them emerge from the house about 1/2 hour before sunset and observe their remarkable flight.

4. Some people think that smearing bat feces on the inside of a bat house may increase the acceptance rate of the house. We are not saying this technique will work. It is used by some. 

Wildlife Damage Control sells bat houses that are built according to Bat Conservation International's specifications. Drop us a line if you would like to buy one.

 

Resources for Bat Houses

• "A homeowner’s guide to Northeastern Bats and Bat Problems." It can be obtained free of cost from Ag. Publication Distribution Center, The Pennsylvania State University, 112 Agricultural Admin. Bldg. University Park, PA 16802.
• The second booklet is entitled, "the Bat House Builder’s Handbook. You can obtain it, for a fee, by writing to Bat Conservation International P.O. Box 162603, Austin, TX 78716.
• Instructions for Building a Bat House