That's what I was wondering.
Short of baiting them with live tethered critters I'm not sure what the options are for tracking them.
We used to get some big Black Snakes in the chicken house.
How to catch a Black Snake.
Attach a #2 fish hook to a thin wire leader.
Attach wire leader to a solid anchor.
Poke small hole in egg, carefully insert fish hook.
enjoy the hilarity.