Sap-sucking Birds

This weekend I was out in the garden and activity on a tree opposite my house caught my attention. On closer examination, I could see what looked like sap running down the trunk. There were a some small holes in the trunk and the sap was seeping from there.

 

The blue tits and coal tits were landing on the trunk and drinking the sap from these holes. I was fascinated… what had made the holes in the first place and was this a common occurrence?

I took my adapted Bushnell trophy cam and I attached it to the tree below the holes, using a Gorillapod. I faced the Bushnell straight back up the trunk, hoping the birds would return and drink, once again, so I could capture this interesting behaviour…..

Please let me know if you, too, have seen behaviour like this in the UK. The only information I could find on the Internet was with birds in the USA.