Oak health question

[Ffmech17]

I was pruning an Oak the other day and on the upper leaders I was finding a bunch of holes I'm thinking from the woodpeckers and at the holes the leaders have developed a black collar about six inches long around them that's real rough. Is this just the tree trying to protect and repair itself or a sign of internal decay that I need to be concerned about?

 

[BC WetCoast]

Got any pics? What size holes? What is the configuration?

What is the condition of the wood inside the hole ie soft/hard?