Where Should You Put Your New Bat House?
Most Important Considerations
Height: Bat houses should be installed no lower than 12 feet off the ground with at least 8 feet of open space directly below the box for the bats to dive out and maneuver back in. This includes tree branches and vegetation.
Temperature: Bats like it hot! But not too hot. Temperatures between 80 and 100 degrees F are ideal. In most areas, this makes it very important to prioritize sunlight. 6+ hours of direct sun is ideal, depending on local weather. The south side of a building tends to get the most sunlight. In areas that cool down significantly at night, boxes do even better when placed on insulated buildings or facing east to get the first morning sun. In most cases, aside from deserts and hot tropical areas, boxes should be painted black or dark brown to help maintain a warm temperature. If two or more boxes are installed near each other, they should have some color difference to provide a greater temperature range. We are based out of Sonoma County where dark colors up to black are recommended, but medium brown shades are best in most other climates.
Guano: Bat houses require minimal maintenance or cleaning as everything falls out the bottom, including poop, known as guano. Bat guano is an excellent fertilizer, but does have some smell to it. Consider where the guano will collect below the box to make sure it is not in a heavily used area like over a door or window. This area should be out of the way for smell and easy to clean. A pole mount is a great option to put some distance from the bats and their guano.
Other considerations:
Bat houses placed within a quarter mile of year-round flowing water are the most successful, likely due to the greater diversity of native plants and the more reliable season-long availability of both terrestrial and aquatic insects. Open ponds in the nearby area can be similarly beneficial.
Tree-mounted boxes have lower odds of occupancy but can still be worth trying if they are tall, clear of branches below the box, and have a predator shield.
Avoid placing bat houses in well-lit locations near yard lights.
Though houses mounted on buildings are generally safe from predators, all houses mounted on poles (especially wooden) require the use of a predator guard.
It is best to try two different locations or colors to provide more temperature variance or find out what the difference in activity is and make adjustments based the actual use.
When to expect bats:
Be patient. It is common to take years for bats to begin using a house. However, after two years without occupancy, it can be worth trying a different location. Boxes may need to be cleaned from wasp nests and spiderwebs after going a year or more without activity.
Springtime is when groups of female bats look for a roosting site to start their maternity colony. They will sync their births together, and typically stay through the summer with the new pups. This is the time of year that bat houses have the most occupancy.