sally H wrote:
Thanks. I'll try tying where I can but otherwise I'll use nails. Are there
any nails in particular you would recommend?

Screws.
Passivated twin-start wood screws with pozidriv or supadriv heads.
Then the birdboxes can easily be taken down for repair if they get
damaged, or moved, and nothing gets left in the tree. Put a smear of
petroleum jelly in the screwdriver recess when finished (or bark
banding grease, or similar) to keep it pristine for years. Come to
think about it, some on the thread should help if you are really
worried about disease, although I would not be, and make it easier to
drive too.