You need to worry your chickens are protected from flying predators in their run, as much from raccoons and others that dig under a run. Hardware cloth on the floor of the run will stop predators. Hardware cloth on the run walls and also on top of the run will keep your chickens as safe as safe can be. No chicken wire. No 2x4 fencing. Both of these a racoon can pull your chicken through...at least capitate them!