Bat friendly house

This sign must have been there for a while, but I recognised it for the first time. It means: "Bat friendly house" and it is given from a national conservation association. It is given to the "Old Forester Home".
I'll ask the owner of the house about that sign - after the Corona crisis.
We have a lot of bats here in summer (very smal , cute and quick ones) and perhaps they have their shelter in that house...

Stay safe and healthy!