The cat was taking particular interest in one outside wall the other day, listened close and heard some clattering and chirping. Took a look outside and there was a hole in the wall right beside the electrical mast
Tried the attic, no dice. Went up the ladder with a little flexible wire camera (like for looking in sewers) and found 2 birds. Managed to get them out after poking them for a while with the camera and screwed some wood over top.
Looking in the hole from the outside, I can see the back side of the drywall. The vapor barrier, insulation, sheeting and siding is all gone. I was thinking about taking out a chunk of drywall and rebuilding from inside the house (so I don't have to be 25' up a ladder trying to fix it).
Mentioned this to a finishing carpenter at work and he suggested a can of spray foam instead. Said it'll fill the void right up and act as a vapor barrier as well.