Bats cannot take off from the ground like a bird. They have to climb up high and fall to gain speed.After seeing 2 or 3 bats soaring around at dusk I decided to encourage them by putting up some houses. I have 2 small commercial ones like those carried at Ace hardware. I then built a rather large one by OWD specs......but in several years now I have not had any tenants that I can tell nor has my population of those soaring at dusk improved. disappointing.