I have been doing my annual clean of my bird boxes. I have three one was used by a pair of blue tits to raise a family. Of the other two one was empty and the other contains what looks like an insect nest of some kind.
I am glad it was of use to some wild life so I don't mind the occupant living there.
My first question is what is it??
Second question is is it still in use??
Third question is should I leave it or remove it?? Are the occupants still using it or will they ever return?? Will birds share with them next year??
I have attached pictures.