2026-02-04 Handout - Laserfiche WebLink

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• Size of House Recommendations on bat house height have increased in recent years. Bigger bat houses, and in particular taller bat houses, can have differences in internal temperatures in different areas of the bat house. This provides a wider range of microclimates so that bats move around in the bat house to find their preferred temperatures while external temperatures change during the course of the day or night, and through seasonal change. multi -chambered houses have been shown to have the greatest occupancy rates. • Number of Chambers Recommendations now favor four over two chamber houses. Having more chambers and larger houses provides more stability in temperature over time, and more microclimates for bats to choose from as temperatures shift daily and seasonally. • Size of Roosting Space Because the bats that use bat houses are species that typically roost in dead or partially dead tree crevices and cavities, or under loose bark, the roosting space in bat houses (i.e., baffles, space between roosting chambers, etc.) should mimic nature by not exceeding 1 inch. This amount of space should also make bats feel more secure because it won't allow large predators such as raccoons or owls to enter the house. • Color The color of a bat house can influence its temperature, but actually the color doesn't matter as much as the shade of the color, or how much white is in it. It is this shading that determines how much sunlight is absorbed vs reflected from a bat house. By painting a bat house a lighter shade, more light is reflected, helping a bat house avoid overheating. By painting a bat house a darker shade, more light is absorbed, helping a bat house in cold climates stay heated. The optimal shade of paint for your bat house depends on your climate, and a variety of range maps recommending color shading are available online. Generally, a light shade is important in hot climates, and avoiding dark shades can be important if even a short period of time gets hot in the summer. • Number of Houses Placed Installing at least two bat houses near each other can provide a range of microclimate options: one to reach warm temperatures (e.g., facing south, east, or west; or painted a darker color); one to maintain lower temperatures (e.g., shaded in the afternoon, or painted a lighter color). Houses should be placed '100 m or less apart; if possible, to enable bats to easily switch roosts as needed. • Placement/Where Bat Houses Are Mounted This factor covers several important design elements: height, sunlight, and clutter. Bat houses should be placed high enough that there is at least 12 ft or m of open space under the exits, so that bats can drop from the house and take flight while secure from predation. Higher is better. Determining where a bat house will get sunlight vs shade is also critical, especially in warm southern climates, where it's important to place bat houses on east -facing walls where they will get morning rather than afternoon sun. Placing bat houses under roof eaves can also shade them from sunlight (shade can also be provided by adding sunshades, awnings, or reflective covers). Bat's prefer locations with early morning sun and at least 7 hours of solar exposure. Also, bat houses should be placed in areas that don't give predators easy access to the house, so in places with no branches extending to the house or other pathways or perches for predators. In some climates, nearby branches can shade a bat house too much, keeping it too cool for the bats. • How Bat Houses Are Mounted Mounting your bat houses on poles is better than mounting them on trees, and mounting bat houses on human houses is even better than mounting them on poles. Trees can block bats' entry and exit with branches and clutter, and they can give predators, like owls, easy access to the bat house. Poles solve these problems, but houses on poles are not as well insulated as houses built against the wall of a human home. Placing two houses back-to-back on either side of a pole can help with insulation and allow bats the option of moving between more microclimates. If placing a bat house on the side of a building, a wooden, stone, or brick building is preferred, as these are thermally stable and will act as "heat sinks", holding the heat from the daytime and reradiating it at night, keeping the bats warmer than the cooler nighttime air. Bats will rarely use a bat house placed on the side of a metal building. An In -Depth Guide with FAA's