Green Woodpecker

They have an undulating flight and skip around tree trunks and branches. They will often move around to be on the side away from anyone watching.

Sometimes they can be seen on the lawn (like this one in our garden) apparently 'eating' ants.  On closer inspection they can be seen to spread their wing feathers on an ants nest pecking at some of the ants crawling in its feathers.  It is thought that annoying the ants so they spray folic acid in a attempt to sting the woodpecker helps the bird rid itself of mites living in the feathers.