I have a fireplace in my basement family room and I noticed a couple of days ago a bat hanging upside down from the mesh screen. The screen is behind the fireplace doors, so I don't think it can get into the house. I don't know if it is dead or not. Over the past 25 years, we have found 2 dead bats in the fireplace. We don't use this fireplace, so I would be willing to leave it if it is hibernating. Is there a way for me to tell?

Bats will use chimneys as places to hibernate if the fireplace is not used. Try tapping on the fireplace doors around dusk to see if the bat stirs. The goal is not to disturb it enough to cause it to take flight, just to see if it makes any movement. It is likely just resting, but it is possible that it got tangled in the mesh. Try tapping first and then let me know how it went. If the bat is dead it will need to be removed, but we don't want a live bat flying around your basement, so for now don't open the fireplace doors.