Put the camera back where it was. Put another camera out, facing that one. Conceal the other camera very well. They won't be looking for the other camera. They'll go to where they expect the camera to be and it will be there.

Of course this is a risk. You could get evidence on them. Or you could lose both cameras.

Perhaps a booby trap. A trip wire hooked to a bag of urine and feces, perhaps?