Bats are a great addition to any backyard - not only are their nightly aerial acrobatics fun to watch during the summer, they are also an excellent source of pest control and will kill loads of those pesky mosquitoes!
One of the best ways to attract bats to your yard, if you don’t have any of their preferred dead trees, is to build (or buy) a bat house! During the summer, there are a couple of species of bats in Iowa that roost in large colonies; the Big Brown Bat (Eptesicus fuscus) and Little Brown Bat (Myotis lucifugus). Females form maternity colonies where they birth their pups and males form bachelor colonies in different locations. These colonies need a place to form and bat boxes in the right location are ideal for this.
Bat Conservation International has conducted research on and tested hundreds of bat houses which resulted in three different box designs that can accommodate 14 different species of North American Bats, including the nine we have in Iowa. Check out their website to determine which design is best for you. If you would rather buy your own, find vendors whose boxes have earned the Bat Approved certification.
Once you have your bat box mount it on wooden posts, steel poles, pivot poles, or on the sides of a building depending on the style of the bat house and the specific conditions of the site where you are putting your bat house. Don’t mount your house on any trees though. Bat houses mounted on trees receive less sun among the branches, make the bats are more vulnerable to predators, and the obstructions like branches and vegetation can make it more difficult for bats to drop into flight. Bat houses are also easier for bats to find if they are mounted on poles or buildings at least 20-30 feet from tree branches. To set up the ideal bat home, mount the bat box with a southern or southeast facing orientation, with little shade, so the spot gets the 6-8 hours of direct sunlight that is preferred. The roosting bats like it warm! Make sure to mount your bat house at least 10 feet off the ground but 12-20 feet is even better.
It may take bats a while to find your bat house, but don’t get discouraged! Your chances will be increased if you mount your box on a building, particularly one that already has a bat colony, and if your site is within a quarter-mile of water. But once they find the house the bats will return year after year.