Build a bats nest in your garden easily with this simple guide. Bats are the only mammals capable of true flight. This comes in handy due to the fact that 70 percent of bats live on a diet comprised solely of insects. Because of the bat’s natural ability to keep the insect population down, many homeowners and gardeners welcome these flying mammals into their yards. If you are interested in housing a few bats, building a nest will help attract bats to your property.