Trail Cameras are great, but where I hunt, camera theft has gotten so bad, that the pawn shops won't even let you pawn them anymore.
I have 15 people that work for me, and we all hunt. Most all of the guys have had at least 1 camera stolen over the last 2 or 3 years. I had 3 stolen 2 years ago off of my lease, and decided enough was enough. My hunting partners and I, decided to put a camera up facing another camera, and it wasn't more than a week, that we got a picture of the culprit. After passing the picture around to some of the locals bordering our lease, we had a name and address. We presented it to the local law, and even though we did not get any of our cameras back, we haven't missed another one the last 2 years.
I got the idea from a lease we had several years ago where we had people driving in all the time during season, and road hunting.
We simply put a game camera up across from the entrance, and had a license plate for every vehicle coming onto the property. We then sent a nice letter to the owner along with the picture, explaining to him that he was trespassing, and that if he was caught again, he would be prosecuted. After about 5 or 6 of these letters, we had absolutely no problems with anyone on our lease for as long as we were there.