Well it sounds like you don't want to loose the hunting grounds so I beleive if you really want to do something about it you have to go hunting. Gotta invest the time.

Don't do it alone, but here's my suggestion............

First and foremost make a report withlocal LE to let them know what's going on and what you have in mind. Then arm yourselves with somegood equipment. Cameras, walkie-talkies, cell phones (with local LE's numbers programed), binoculars, notepads and pencils. Then go hunt those trespassers just like you would a deer (although scent-killer proboboly would be over doing it- LOL).Seclude yourselves, waitand observe.

See what ya catch, but I have to strongly suggest you not confront any armed individuals.