I'm forever blowing bubbles

Dull with intermittent showers.

Our friends ValC and MrC called for coffee this morning and Val brought me a RSPB pocket guide to British birds. So hopefully some will stay still long enough for me to spot any relevant features!!

As always lovely to see them and whilst here we were commenting on the birds when we noticed some bubbles running down the tree trunk from the birdbox. So failing any other photos today thought I would see if anyone has the faintest idea what it could be?

Hope the weather improves.