I changed my strap with a small screwdriver. The pins that hold the strap on spring outwards into holes in the watch, so you just push the end in with the screwdriver and slide the pin out of the watch. You can change the straps back if you want, but it is a bit of a faff about. It took about 5 minutes to change the strap. You put the pins back into the watch after you take them out of the leather strap, then you just thread the NATO strap through the pins and loop it through the metal loop. I can post pics if you need a demo.
As for the deer, not too sure how you would stand legally as it may be on private land and be owned by that land owner.