If you use a tree, make sure you place a shield around its trunk. Although this is not necessary when you first mount your house, as soon as bats move in they will become the target of many predators. Such predators include raccoons, cats and rat snakes. To stop them from raiding your bat house, place a sheet metal band two feet wide around the trunk of the tree and mount it eight feet up. Do not place it too low because some animals may jump over it.
Bats prefer to live within a mile of a stream, river or lake .
Having some sort of night light close to your house or mounted below it will attract many insects which in turn will attract bats. This appears to be one way to attract bats to your house. Bats tend to be opportunistic and they can see well. Once they find an ongoing supply of insects adjacent to your house, the house becomes a logical place to roost. This lure is made from Bat Guano along with some special secret components which bats will smell.