I, too, had this same problem with all kinds of predators, flying, crawling, climbing, etc. I was a newbie and very naive and my chickens paid the price. But I also learned from this. I bought aviary netting, I bought welded wire. I bought "night-eyes". I predator-proofed EVERYTHING. The coop and run are a Fort Knox of chicken safety. Gone are those horrible days when I came home to missing or dead chickens. I do let my chickens free range but I am with them the whole time they are out.
I understand you want your chickens happy. It hard to see their little faces at the coop door wanting to be let out but I'd rather they be alive. Maybe you could enlarge their run? Or, what I do is get a wheelbarrel of last year's leaves digging down to get the wet ones where the bugs are and dump it in the run. This keeps mine entertained for hours. Make a dust bath box. Put some large branches in the run. Throw in piles of clover, weeds and grass. All this will break up the bordom of the chickens having nothing to do.
Chickens have no defenses. That is why EVERYTHING eats them. Please keep your babies in the run unless you are right with them when they go out.
