I believe these are bat feces due to main accumulation in two spots beneath the rafters, though there is no bat odor. Aside from accumulation in two main spots, they are also scattered more thinly across the attic. Four flying squirrel traps caught nothing over 4 days. The customer swept up the feces so we will see whether more show up. I suspect it was a few bats, and perhaps that they have migrated away.

But she is claiming to hear some critter in the duct work, which you can see in the photo. It seems to be a tight system. I'm not sure how to approach it. Cut a hole in the duct to inspect and set a trap?? Any suggestions here? The house is quite tall and the vents outside are high up the side but seem to be covered and in good shape.

Definitely bat feces. She has a few bats roosting there during the summer months. If the droppings continue to accumulate at this time of year she has some wintering bats. However many wintering bats will move to more well heated areas for that time period.

You may need to do a real good inspection of the insulated foil wrapped duct work to determine if there is a breach in the exterior foil. Squirrels are good for that. The hole(s)may be tight to the floor and inconspicuous at times. Other times they are quite obvious.

Run a couple trail cams in suspected areas of the noise activity. They can be very useful tools in these cases.

You need a good eye to identify some of these spots at times or you may get lucky and find some chewed pieces of foil. These places should get you to inspect a little more closely in that area.

Thank you, Bob!

I did suspect that about the bats.

Would the critters in the duct actually be inside the duct, or just in between the foil and the duct? I don't know exactly how they would get inside, though I'm not an HVAC guy. Also, would the bats use the ducts for warmth? I don't really suspect that.

If the foil is loosely wrapped in some areas it is possible for bats to move between the foil and the tin. They are very flat and can squeeze through some very tight spots if need be.If they do this, it can be noisey in some areas of the house that is near these areas.

It could be squirrels are running around on the tin surface which would be quite noticeable in a quiet area of the home. Particularly if this is occuring in the later evening hours it is may likely be flying squirrels. If the noise seems to be traveling quickly it may suggest they are in the duct work.

Remember, bats or squirrels may have a difficult time climbing a vertical interior tin surface if the joints are far enough apart. So this noise will most likely be limited to the more horizontal surface areas.

I would check to see if there is any flexible duct work that has been used to connect the tin duct work. These are very high risk chew in areas for squirrels in particular. Many times this is used in wall void areas due to its ease of use.

Many thanks again, Bob.

-John

She just fired me lol. She hired me to solve her mouse problem.
I politely said it bats not mice, but now let’s figure out what's in the ducts.

Five days is too much for her. So she is calling a pest control company.

I guess I should have addressed the ducts earlier? But I didnt
know the ducts were a problem.

First time fired.

She said send her a bill. I don’t want anything.

Tell her that.