You may have borers he is after..Severe lack of knowledge here....so
http://www.unitedwildlife.com/AnimalsWoodpeckers.html
Thank you, Meg.
My tree was treated last year for any bugs - so it is not bugs he is after. The Arborist told me he is addicted to the sap from that tree. The poor tree is in serious danger, and several have suggested shooting the bird. (He pecks away right in front of me - nothing scares him.)
I could not shoot him - but am thinking of filling a squirt gun with amonia - and squirting him. It will smell bad but I don’t think it will hurt him. After a couple squirts of that, while he’s enjoying his “sappy hour”, he may be deterred.