Taking down a trespassers' game camera and turning it over to local wildlife enforcement is not theft. I generally call the wardens out and have them photograph the camera on the tree and document the case well, then I forcefully remove the camera. If removing it with bolt cutters and an axe causes damage to the poaching equipment - as hunting activities on property without permission is so viewed in my state - then so be it.
But I live and own property in states where private property is that, and trespassing is trespassing.