I watched the bats emerge from the new nursery house last evening, and I counted 23 Little Browns emerge. I didn't see any Big Browns. After they had all left the house, I shined a light up into the house, and was able to count 12 babies and 4 adults. The adults all looked like Little Browns.
I am pleasntly pleased to see them using this new house, just a few months after I put it up. Since it is just under 14' high, I wasn't sure it would get used, but that doesn't seem to have been much of a problem.
Another interesting thing was when the bats emerged from the house, they all went south, towards our house. Normally, when the bats emerge from the regular bat houses, they all go to the northwest towards the creek. The difference may be because the new nursery house is on the south wall of the barn, while the other houses are on top of a 20' pole.