How to build a bat house in your backyard

How to build a bat house in your backyard

For decades Europeans have practiced insect control with backyard bat boxes, small wooden shelters similar to birdhouses where bats roost. Once established, a bat colony can effectively cripple a local mosquito population.

According to Dr. merlin D. Tuttle, the founder of Bat Conservation International (BCI), an organization devoted to bat education, “Residents of the famed Chautauqua summer resort in New York do not use pesticides. For more than 50 years they have encouraged bats to live there as an alternative to chemical forms of mosquito control and they report great success. I walked the streets for three summer evenings and sure enough, I wasn’t bitten once.”


In the United States artificial bat houses were pioneered in the Midwest. The first bat house was built in Missouri and provided shelter to hundreds of bats. The success of the prefabricated bat cave led to the construction of twelve “Missouri-style” bat houses in Minnesota parks. In response to the popularity of these projects, BCI designed smaller versions of bat boxes suitable for backyards.

And a strange and welcome scenario began to unfold. For the first time since its finding in 1982, Bat Conservation International started to get more requests for bat houses than frenzied calls about eradicating bats from attics. And bats need homes. Natural roosts such as caves and hollow tree trunks are becoming increasingly scarce.


Backyard bat houses are popular alternative roosts. The most successful bat houses flourish near a permanent source of water, a lake, or a large stream being preferable. Bat colonies prefer stable temperatures from 80 to 100 degrees and bat boxes should be oriented to receive maximum sunshine. A bat house can be mounted, ideally 20 feet high, on trees or free-standing poles but houses attached to building sides provide greater temperature stability. The approach to the house should be unobstructed be vegetation and utility wires.

A new bat host must be patient waiting for guests to arrive. Roosting behavior is not completely understood but a year to 18 months is a typical waiting period for a bat colony to roost. Some houses may be occupied immediately and some may never entice bats to roost. Two or three bat houses oriented differently can increase the chances of bat habitation.

Conditions for your bat house need not be perfect for it to be occupied. Even natural roosts are seldom ideal. Most bats will migrate south or find safe hibernating sites for the winter. Hanging a bat house in the fall or winter can prompt occupancy the following spring when migrating bats return.


There are 1,000 known species of bat in the world. Some of the more common types include the little brown bat, the big brown bat, the silver bat, the hoary bat and the red bat. Far from their dull gray image, many bats are strikingly colored.


Not only are bat colonies an ecologically friendly alternative to pesticides but they complement today’s organic gardens. Dropping that tumble out of a bat house provide excellent fertilizer, rich in nitrogen. Unlike electronic bug zappers, bats do not frighten insect-gobbling birds from the area.


Is it safe to live in close proximity to bats? Like all mammals, bats can contract rabies but few, less than one half of per cent, actually do. Bats are shy animals and even when rabid they rarely become aggressive. Indeed, a rabid bat dies quickly from the disease and in nearly a half-century of record keeping in the United States, but only 15 people are believed to have died of bat-borne rabies, far fewer than annual deaths from household pets. The chances of being harmed by a bat are extremely remote, especially if the animal is simply not handled.


Far more common is the harm we do to bats. Millions are killed each year by vandals with rifle fire which deafens the sonar-dependent bats. Even well-meaning cave explorers endanger bats by awakening them during hibernation.

Insulated with only a thin layer of winter fat, a prematurely aroused bat will fly frantically about, use up its fat supply, and die. Nearly two dozen species of bat have threatened with extinction in North America and in the United States, nearly 40 percent of our bat species are on the federal endangered list or are candidates for it.


Building a bat box is essentially the same as constructing a bird house, but the entrance will be underneath and not through a hole in the front. The crucial elements of a bat box are a removable lid or front piece to inspect the interior of the box and the size and position of the entrance. The entrance must be a gap underneath the house that is less than six inches wide, which is large enough to allow bats to climb in but small enough to keep other animals out.

Since the objective of a bat house is to recreate a hole in a tree generally found in nature, the preferable building material is rough sawn planks. Do not treat the wood with preservatives as bats are extremely sensitive to wood treatment chemicals and will be repulsed by the strong smell. Metal plates can be placed near the entrance way to keep squirrels and woodpeckers from trying to enlarge the opening.

The size of a bat house varies but generally it need be no larger than a brick. The back piece of the bat box should extend down beneath the rest of the box which will allow the bat to gain entry to the opening by landing on the back plate and climbing up into the interior space.

The bat box is attached by connecting the back plate to a pole, tree or building with screws or nails. To avoid damaging trees, the bat house can also be attached with bands.

Enjoy your new accessory and the insect free summers!!


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