Ceilings with no access

Just wondering how you guys determine what is in a ceiling where there is no attic or other access to the space? I had one recently the clients insisted squirrels and my best interpretation of their description of what they heard (without hearing what they did) was bats (which I don't do). After removing 4 red squirrels that may or may not have been in the ceiling (no obvious access point, but they definitely could get between foundation and siding if they wanted to) they still have "scratching noises" as much or more than before I started. There are no vents of any kind in the whole cabin and the log siding is caulked well with no squirrel sized access holes (other than between foundation and siding, which I have since sealed after removing the squirrels and monitoring soft blocking). There are a few small access points that bats could exploit, but how do you go about proving this is what it is when there is no access to where the hear the noise and no guano to be found anywhere. My guess is start removing soffit, but since there is DEFINITELY no way squirrels could access there, and I don't do bats, I stayed away from it.

I'm stumped and they have a bat guy coming to do an inspection...I'm stumped and removing myself from the situation.

Curious how you guys would go about this one?

It's been my experience, when a customer says they hear scratching in the attic, it's usually mice.

Time of occurrence is important. If they hear the noise in the evening and night, mice. If they hear it in the morning and daylight hours, squirrels. Of course, flyers are the exception to the rule.

I would think keeping an eye open at sunset would clear up the bats/no bats question.

This right here, Putting a bat cone on after access found and sealing up other points is easy money and keeps that customer as yours

Seal it for flyers and you've sealed it for bats. Use the same exclusion cone. And you've solved the problem with out doing bats.

Now if you sealed the lower section too, and threw out mouse traps, you'll take care of that problem too.

Great advice so far.
BUT....
Bats are way easier than squirrels IME, so I am stumped on why you won't do them.

If you see bats at dusk, just use a pc of tarp or plastic...you can make your own "cone" if needed to do both, with empty caulking tubes. You have been saving them, haven't you?

Lots of interesting takes. The suggestions of mice got me thinking a bit. I actually caught one in a swing panel, but attributed it to coming from outside, not inside. Are there ever any bat infestations with no guano a entry points? I am definitely not a qualified bat guy and have one-way doors out to rule out flyers. It's been a week with no action so it has to be bats or mice at this point (both of which I don't do). I am headed there Sunday to retrieve the one ways.

So how do you actually figure out if it is mice since they can't really be seen in this case?

When the noises are heard can give you an indication of what it is. Also, bats don't run across ceilings. Banging on the ceiling will often make a rodent scurry. Bats don't care. Snow on a roof can often tell you if there are flyers as they will land in the middle of the roof. Are there mice droppings in the basement?

They heard noises both at night and early morning. I just can't find any guano anywhere so I'm starting to question that it could be bats. They said the noises "moved across the ceiling" but there was no distinct running noises. They also said it moved slow and banging on the ceiling didn't bother it. I am starting to think it was both squirrels and mice and now all that's left is mice.