A new hole is interesting

I made a round hole (80mm) to wall because we need more controlled ventilation in our old house, more fresh air from outside. Air shouldn't come in indefinite holes and worst case - from toilet. Fireplaces and extractor fan etc needs to have fresh air and of course quality of indoor air is important to us.

And the point is: after drilling the hole couple of Great Tits (BIRDS!!) (:=) came to observe the new hole that a nice uncle did for them.

Picture have been taken through the window, bird is sitting on ladder.