On Sunday we not only put up our owl boxes, but we put up a bat house as well. G and DIL gave us a bat house for Christmas (made in Nova Scotia, of course) and we put G to work on Sunday mounting it on one of our telephone poles.
According to the tag on the box, bats' needs are simple: a place to roost and a steady diet of mosquitoes (yes, we have lots of those in the warmer weather!). This house will act as home to dozens of bats at a time. The grooved backing provides a place for them to cling while roosting. The house should be placed between 10 and 14 feet high on a building, pole, or tree. If you want females, the house should have a south-east exposure (which is what we did) or a west exposure for males.
I checked the internet to see if we should prefer to have females or males. Females will have their young in the box, so we went with the exposure for females. (figuring that they might need protection more).
Of course, John read that owls eat bats. So now that we have 2 owl boxes up, I guess we've also given them a food supply if we have bats show up. Our fields have plenty of rodents though, so hopefully the owls will leave the bats alone. Time will tell.