This is absolutely true, not only can you get sued (anyone can sue anyone else at anytime for anything), in most states it is illegal. Even though it is your own land, most states have what is called a "man trap" law where it is illegal to intentionally set any kind of "man trap". This came about from people setting spring loaded firearms traps for burglers, etc. and people who they were not intended for (kids, employees, etc) getting thumped by them. If you dig a "lion trap" and some dumb 12 yr. old kid breaks his neck in it, even though he wasn't supposed to be there, I can promise you there will be hell to pay...and hell is damned expensive all year round.

Your best option, though not always practical,is surveillance.