It looks like many holes up and down the branches of my birch tree, what could it be?

Its not woodpecker holes. It is wood boring insects and the tree may have to come down.

If you have a local collage nearby, see if they have anyone on staff that can look at the tree for you.

Sometimes you can spray the tree and save it, however, if it is to far gone it will have to come down.

Don may be correct but it may also be from wasps or ants. How large are the holes?

It llooks like the answer is yes, the woodpeckers are getting to the tree, but the reason is they are looking for the bugs that are moving in the tree... go figure!!

I was going to ask why it couldn't be a woodpecker? Because it's a Birch?

I had a tree with bugs, they moved to the house (carpenter ants), where we found sawdust. Expensive problem.