Becoming a Bat Host
(Building a Bat House)
by Pete Cecil of Bend, OR
Why bother building a bat house? North American bats have, like bluebirds, suffered serious loss of habitat and are in desperate need of good homes. Nearly 40 of America’s 43 bat species are listed or are official candidates for being listed on the endangered species roster. Bats comprise almost one-quarter of all mammal species, and they form an integral part of a healthy sustainable ecosystem. Bats disperse seeds, pollinate flowers, and are major predators of night flying insects. Rootworms, cutworms, stink bugs, and corn ear worms are among the many favorite meals of the common bat. A single bat can consume up to 500 mosquitoes in one hour! A simple and inexpensive step towards improving bat habitat is to provide bat roosting houses (approximately $15 per house) around your property.
Constructing a bat house is quite straight forward and only requires a few basic wood working tools. You will need a hammer, saw, tape measure, and a pencil. The house is constructed from five feet of 3/4″ x 12″, and two and one half feet of 3/4″ x 6″ rough sawn boards. Chemically treated and painted boards should not be used. If rough sawn boards are not available, cut 1/16″ deep saw cuts across all of the interior surfaces – this allows the bats to grip the wood. Almost any species of wood can be used for the house – fir, pine, and cedar are easy to work with and are available at most lumber stores.
Cut out the pieces according to the plan. Overall building dimensions can be adjusted to suit your materials. The interior partitions need to be spaced between 3/ 4″ and a maximum of 1-1/2″ apart. Securely nail the pieces together. Forty-six galvanized five penny box nails will be needed. I usually start by nailing the sides to the back, then adding the interior partitions, with the front and roof being nailed last. Gluing the joints with waterproof adhesive will give additional strength.
Your new bat house should be hung 12 feet above the ground and oriented to catch the morning sun. It can be mounted on a tree, pole, or the side of a building. The front and bottom need to face clear airspace (so the bats have an unobstructed flight path). Bats also prefer sites that are protected from the wind, and have an interior summer daytime temperature of between 80 and 90 degrees. Locating the house so that it catches the morning sun and painting the roof black will help increase the interior temperature. A source of drinking water (such as pond, irrigation canal, or even a stock tank) should be located within 400 feet.
It may take up to two years for a group of homeless bats to take up residence in your house. Hanging your bat house before the beginning of spring will increase the chances of it being used. Once occupied it does not need to be cleaned. Many bat species live up to 20 years and will reside in the same dwelling for life. If you decide that building a bat house from scratch is too much work, they can be purchased in kit and finished form from an organization called Bat Conservation International (BCI), Inc [www.batcon.org]. BCI is dedicated to the preservation of bats and their habitat, in America and around the world. They are an excellent source of up-to-date information. When bats have become an integral part of your natural environment, you will find them to be interesting, considerate, quiet, and helpful neighbors who don’t deserve their long held negative public image!
For further information contact: Bat Conservation International.