If you have bat houses near water or want to keep temps lower to hold big browns , you can use a PVC vent pipe.
Near the water use a couple of sections of PVC vent pipe and a 45degree elbow . Screen both ends of the pipe.
Mount the PVC pipe on the post and have the 45 degree elbow connected to the top of the bat house. The cool air from the water will help keep temp lower in the bat house. the lower end of the PVC pipe is 6 inches above the water. Cool air will rise and help lower bat house interior temp.
If you are not near water dig the PVC pipe into the ground and connect to the bat house , also will help keep bat house cooler.
It is not neccessary to mount the bat houses over 10 ft from the ground for big browns , so as not to need long lengths of PCV pipe.
The 2" outer and inner roofs works well also to hold the big browns.
Have held very large nursery colonies of big browns and northern long-ears myotis at one site for over 10 years. The houses are mounted 10 1/2 Ft from the ground to the bottom of the bat house.
Sometime will take some photos of 8 large bat houses mounted 6 ft. to bottom of bat house inhabited by hundreds of little browns - nursery colonies.
Thanks Kent, have you noticed big browns preferring bat houses mounted on buildings and little browns preferring bat houses mounted on poles? I am noticing this trend more and more here in nw pa.
