I have worked on a few houses with bats under the siding . One for sure when the siding was removed the bats were there. The other two are probable. Noises in the wall no sighn of rodents or insects no veg near the home. A process of elimination.The first thing a bat does when exiting a dwelling is poop , it is usually easy to find the entery points. This time of year not so much. Ice on the puddles yesterday kinda cool in the daylight hours. No insects for these guys to chase. Prob the very early stages of hibernation .
Need noises gone ! Will not rip siding off house. ??????????????????????????? Deer mice could be a distant second . Paraffin block rodenticides have a poor track record with deer mice and they could forage on the exterior leaving very little evidence . need help !
thanks Bob

Might not be legal to evict bats this time of year. Clack with your conservation department.

I'd probably go the rodent eviction route. Regardless of what it is, you should see signs of entry.