One thought I haven't heard mentioned is that a heavy-handed confrontation, besides being a potential threat to someone's life and limb, may actually do very little good. Sometimes I'm sure its gotta be smarter to keep quiet, rport the activity, and hope for the best.

The deer poacher post above is a good example. Hard as it may be, not saying anything to the guy would do much less to put him on the alert. He knew someone was on to him, and they had packed up and were leaving because of it. It was lucky they weren't long gone before the warden got there. Without a big confrontation they would probably have been sitting around the fire eatin' backstrap.

Worked in that case anyway, but sometimes the non-alerting method might be best.