Walking under a canopy of mainly Oak trees in the parkland I could hear the call of a Green Woodpecker very close overhead of my position. This repeated several times while I was trying to locate the bird. At the top of the Oak I was under, I found the male bird and started shooting images as in the first three below.
I then noticed more than one bird running around the branch of the tree.
The very poor quality images below show what was happening.
Note from the image below that one of the birds has its hackle up, indicating a show of force to the other bird. It transpired that this was two males having a territorial dispute.
At this point in the image below you can see that one male is making a hasty retreat.
The other male shown here below is still showing an aggressive stance.
I couldn't relocate the other bird, but you can see from the image below that this male can still see the other.
Peace was restored.