Bat Box

One of the most surprising changes to have taken place during the last 15 years is the new way many people view the natural world around us, Accelerating deterioration of the environment is making it difficult to deny that the assumptions behind conventional ideas of progress are seriously flawed. Old ideas be reexamined, reworked, and made new. This new view includes seeing the world as an interconnected whole, not just a series of fragmented parts. Bats are creatures we’d be wise to include in this view. Some people say it’s essential that we do. One of these is Dr.Merlin Tuttle.

Concerned about rapidly declining bat populations world-wide, Dr. Tuttle formed the non-profit organization Bat Conservation International (BCI) in 1982, Based in Austin, Texas, and dedicated to the research and promotion of bats as harmless creatures. BCI has compiled a large body of knowledge to support its purpose. Building a bat house for your property is a good first step toward cultivating an understanding and appreciation of
these interesting animals. If this idea scares you, perhaps a few facts will put you at ease.

  1. Bats are mammals. Females usually give birth to and nurse only one pup per year. For this reason, bat populalions grow very slowly and are especially vulnerable 10 devastation.
    2. Bats are not blind. In fact, they have excellent vision and use echo location
    to track down their prey much like dolphins do. They do not get tangled in people’s hair and are no more likely to carry disease than any other wild animal.
    3. The little brown bat (Myotis Iucifagus) and the big brown bat (Epresicus Fuscus)
    are two of the most common species found in Canada. One little brown bat can consume 600 mosquitoes per hour during its nightly feeding flights.
    4. Bats in other parts of the world are essential for pollination of hundreds of
    different kinds of plants (including avacados, bananas, mangos, and peaches) and the dispersal of seeds necessary for the regeneration of the rain forests.
    5. Bats in Canada either hibernate or migrate south during the winter. If awoken by human disturbance while hibernating, one little brown bat will consume enough fat stores to sustain it for 67 days of sleep. Several of these disturbances will kill them.

The bat house design presented here is a of research gathered from several sources and incorporates the latest features intended to appeal to the kind of bats found in Canada. Unfortunately, there’s still a great deal to learn about bats and their housing requirements. For this reason, it’s not possible to guarantee these creatures will move into a house simply because you’ve put it up.

Recent experience shows that bat houses are most effective when placed near buildings containing a nuisance bat population. Blocking up their entry holes after dark can result in the colony moving into the bat house out of necessity. There have also been reports of them moving into houses without being intentionally evicted from neighboring buildings, although this process can sometimes take several years.

Whatever the experience of others, and wherever live, it’s still worthwhile to build a few houses, put them up, and see what happens. If nothing else, they’ll stand as a symbol of your conservation ethic and provide many opportunities to introduce others to the value of these helpful and misunderstood creatures.Over the years, researchers have discovered that the following features should be incorporated into anything you build to attract the kind of bats found in our put of the world:

  • an internal structure of partitions arranged with a 3/4″ space between them
  • Rough, unfinished inner surfaces to allow bats to climb up and around inside the structure
  • A construction style and level of workmanship that leads to warm and dry conditions inside the house

To these three points I’ve added two of my own:

  • a variable width crevice/ledge, My own observation of the little brown bat (most common species in my part of the country) has shown that they can crawl through openings much narrower than 3/4″. They also seem to prefer horizontal ledges at the openings of their favorite crevices. The variable width crevice/ledge found on both sides of the house allows experimentation that may lead to a understanding of what bats prefer
  • the house should be simple to construct and easy to mount on buildings or trees

Fig. 1

Fig. 1 is a cut-away view of the front of the house showing the internal structure of the partitions. These partitions are made of 1/2″ sheathing grade plywood and are the same size and shape as the sides of the house, which are made of 3/4″ pine.
Fig. 2 is an overview of all the required parts, with dimensions and angles. Create everything you’ll need for as many houses as you’d like to build now. Each one will require two sides, six internal dividers, and one each of the front, back, roof. and mounting bracket. To incorporate the variable width crevice/ledge feature, you’ll also need a couple of small strips of pine, also shown in Fig. 3.

Fig. 2

Assembling this project is simple. Use 2 1/2″ ardox finishing to attach the front and back members to one side of the house. Allowing these parts to stick out 1/8″ to 1/4″ beyond the side makes this butt joint look more attractive than if joined flush, (see Fig. 3).

Place the other side member tight against the inside surface of the side you’ve just nailed on, in between the front and back pieces. This second side member will act as a temporary 3/4″ spacer, against which you can place the first of the plywood dividers. Fasten this divider to the front and back pieces with 1 1/2″ finishing nails, four through the front and five through the back of the house. Use a small scrap of wood and a hammer to gently tap out the 3/4″ side piece/spacer from between the plywood divider and the pine side member. Repeat the process by replacing the spacer against the other side by the divider you’ve just installed. Slip another divider between the front and back pieces (tight against the spacer) and nail it in place as you did the first. Repeat the process by removing/replacing the spacer and installing the plywood dividers until all six are in place, each with a 3/4″ space between them.

Since the nails used to fasten these dividers are such a noticeable part of the front Of the house, it’s a good idea to drive them in a straight and regular pattern. Use a square to help you draw faint pencil lines on the front of the house to guide you if necessary. Finish up by installing the second side member (used previously as the spacer) and the roof.

The house featured here has been stained a medium brown color and finished with Sikkens Cetol #1, although a number of other durable products could be used instead. Exterior grade house paint will work well for people who aren’t interested in allowing the natural appearance of the wood to show through in the finished house. Whatever product you choose, it’s wise to finish the house, mounting bracket, and crevice/ledge strips separately in order to protect the wood as completely as possible.

Fig. 3

When you’re ready to install the house, attach the mounting bracket to the back of the house with five #12 x 1 1/2″ screws, countersunk below the surface of the bracket. Since bats prefer warm locations, install the house where it will get as much direct sunshine as possible. A southern or southeastern exposure is very important. Locations 12′ to 16′ off the ground on the side of a building near permanent sources of water seem to work best.

This plan can be originally found at

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