[Baz]

Hey Alex.....I'm not very educated on Birch trees and can't really tell from your photos what's going on. I suggest you contact a local tree service or if you have a local branch of your Agriculture dept with someone versed on that species who could offer some insight.

Sorry I can't help more. Losing a tree sucks but it will give you a space to re-plant something different and that's always a positive.

Good luck!