Thank you for this. Please correct me if I am wrong but in the UK bats are domicile based and not migratory.
This is a fundamental difference between UK & USA, so much of your post is related to migratory bat characteristiics.
My point is a £few,000 cost of a survey wont stop a wind farm project development but a mandatory bat survey may stop a totally valid smalll scale project as ROI would decrease by 25-90%, even if there are no bats at risk. That cannot be right.