To see pictures of a completed bat  house click here.

Here are a few tips to help you build a  better bathouse. You should remember that building houses  for bats is a recent development and that there are  different ideas about what will work and where it will  work. Adjustments will have to be made to the design and  sun exposure depending on what temperature zone you live  in. If you put up a house and it doesn't attract bats  that does not mean there are no bats around, or that the  house is a bad one. It may be that changing the outside  color of the house, and thereby changing the interior  temperature, will be all that is needed to fill up an  empty house. Also, in almost all but the hottest areas  bat houses will probably do better if they get at least 6  hours of direct sun a day.

Design
A bathouse should be around 2 feet tall and14 inches wide  with a 3 to 6 inch landing strip extending below the  entrance. The inside of the house should be divided into  chambers. A good number of chambers is 2 to 4. Too many  and the inner areas may not benefit from solar heating,  too few and the temperature may flucuate too much to suit  the bats. A one or two chamber house can be successful if  mounted on wooden or stone buildings to help keep the  temperature more steady.

The chambers should be spaced so that they are 3/4 to 1  inch front to back. Larger bats may prefer the upper  range and smaller bats the lower, but this is a good  general purpose size. One surface of each chamber should  either be roughened or have plastic screening stapled to  it. The screening should have a mesh of 1/8 to 1/4 inch.  The landing area should also have a rough surface or  screen mesh.

There should be a 1/2 inch ventilation slot across the  front of the house 6 inches from the bottom. Also there  should be a vertical 1/2 inch ventilation slot, 6 inches  long, in each side of the rear chamber. These ventilation  slots allow for cooling on days when the temperature gets  a little too warm. The slots should not be over 1/2 inch  to keep sunlight entering the house to a minimum, and to  help keep put birds or other pest. In very cool areas the  slots may not be needed at all, and in very hot areas the  houses may need to be placed in areas of more shade to  keep solar heating to a minimum.

Construction
Bathouse fronts, backs, sides and roofs can be built out  of 1/2 inch plywood or standard 3/4 inch lumber. For the  interior partitions the use of 1/4 inch plywood will cut  down on the weight of the house, and quite probably the  cost too! A quick and easy way of installing the  partitions would be to cut the boards for the sides out  of standard 3/4 inch thick stock and use a router to cut  a groove for each partition to fit into. Just be sure to  allow for the width of the groove when picking out the  lumber. One inch per chamber should be fine, 3/4 inch for  the open space and 1/4 inch for the groove/partition  board. All seams should be sealed with caulk, especially  around the roof.

Wood treatment
All outside surfaces should be painted with at least two  coats of exterior latex paint. This will protect the wood  and help keep out moisture. In areas where the average  high temperatures in July are 80-85 degrees or less the  house should be painted black to get maximum benefit from  solar heating. In areas where the temperatures are  between 85-95 degrees they should be painted dark colors  such as dark brown, grey or green. In areas where the  temperatures are 95-100 degrees they can be painted light  colors and in areas over 100 degrees they should be  painted white. This is an area where some experimentation  may be necessary. The idea is to keep the temperature in  a range that the bats like. Due to other factors such as  hours of direct sunlight per day, etc, these color  schemes may need to be modified accordingly.

The inside of the house should be left untreated!

Sun exposure
This is something that can have a great affect on bats  using or not using a bat house. It seems that bats like  the house to be exposed to at least some sun in all but  the hottest climates. A general rule seems to be that bat  houses should receive at least 6 hours of sunlight a day  if this can be done without overheating the house. This  involves a little give and take between sun exposure and  the color of the house. In color climates the house will  need to be painted a darker color to absorb solar heat.  In hot climates the house will need to be painted lighter  colors to avoid becoming too hot.

Habitat
Most nursery colonies of bats will be found within 1/4  mile of a water source such as a stream, lake or river.  This could in part be due to the higher numbers of  insects found around water or wet lands.

If you see bats around during the summer then chances are  good that you can attract them to your house sooner or  later, if you build it to their liking.

Mounting
Bats seem to like houses that mounted on poles or  buildings more than those mounted on trees. This may be  due to it being just plain easier to get to it if they  don't have to fly through limbs and leaves to get home.  Or it may be because the leaves on the trees block the  sun from reaching the houses. The height should be around  15 or 20 feet. A good location would be along the edges  of streams or rivers, or along the side of a wooded area.  These seem to be good bat areas, probably because there  tend to be more insects in these areas.

Protection from  predators
Probably one of the worst predators for bat houses would  be snakes. If you live in the country you probably  already know that snakes can climb just about anything if  they take a mind to. You may want to use some kind of  guard if you mount your houses on poles. This can be the  same type of guard used to keep squirrels out of bird  feeders. A simple design would be an apron around the  pole that stands out at a right angle. This apron should  be mounted 4 ro 5 feet from the ground and stand out at  least a foot so that it is hard for the snakes to just  climb around. Another way would be to use a large  diameter pipe, 10 inches or so and about 2 feet long,  with screen across the top. Cut a hole in the screen for  the pole to pass through and secure it in place. A snake  going up the pole would go between the pole and pipe, hit  the screen and hopefully give up. Always keep an eye on  your houses to see if you have predator problems. If you  have bats and they leave suddenly then you probably have  a predator problem. The bats probably will not come back  until you remove the threat.

Importance of  experimentation
Building and installing bat house is a relatively new  thing in the US. There don't seem to be any hard and fast  rules other than the need for constant and warm  temperatures. This is an area that is wide open for  experimentation. If you don't have success the remedy may  be as simple as painting the house a different color or  moving it to a new location. If you have more than one  house you can try using different colors on each one and  see which does the best for you. Try mounting them in  different locations, or facing in different directions.  When you hit the winning combination make a note of all  the details. Then you may want to add other houses made  the same way and mounted in like surroundings.

Feedback
I would love to here from you on how your bathouses turn  out. If you hit a successful combination share the  information. It would be nice to get tips from people in  all parts of the country on what they did in their area  to make their bat houses successful. To send me e-mail  just click here or send it to jdwiggins@infoave.net