Why not have a purge on the cats before hand mate .You dont have to kill them ,just trap in one of the many feral live catchers and re-locate .Alternatively ,put a smelly baited cage near the crow catcher and kill two birds with one stone ,so to speak .
I do know ,as you will know probably ,that some cats get trap bound , that is to say that they will be caught in the same trap ,same bait ,same place, time and time again and you have no chioce but to re-locate to a hole in the ground .Good luck with your trapping and keep us posted .