Hmm...good topic. We have chickens. 14 in the big kids pen, and 6 chicks in the broody chicken tractor. We lock the big kids in at night, behind padlocks on both doors. But that is not to say something might not get in. So far, we have had neighborhood dogs, a resident fox, a roadkill possum and raccoon, snakes, and the ones flying over head of course. The neighborhood dogs have attacked my flock 3x I think in the past 2 years we ahve had them. They were the OEGB flock though, which had no clipped wings. They were able to escape for the most part. The initial attack was when we were culling the 7 cockerels that sexually matured all at once. I didn't lock them up that night, only putting them in 18"x18" block cages outside of the chicken tractor. The dogs came in at 4am that Saturday morning and obliterated them. We knew when it happened, because we had them in the front yard right outside the door. But it was too dark to see at that time.
We live. We learn.
So now, we have LF..Plymouth Rocks, an Easter Egger, 1 game hen left..and the new kids. 5 OEGB mixes-16 weeks, and 7 PR/PR/EE chicks....4 weeks.
The chicken tractor is Fort Knox, large dog tested. Fox tested. And it pretty secure. But things could get into the large coop and pen. Mostly animals that could climb, pry or dig. The neighborhood dogs are too big to bother to be successful, and would give up. But the fox has to feed babies usually.
So, every day, I check the perimeter of the big pen, and the tin shed coop. Checking for any predative activities. Clawing, digging, smells, wall damage, etc. We ahve the 30'x32' square pen covered with bird netting. But that is mainly to keep our games inside. The LF grow too heavy to attempt escape, but I have seen the roos smack the netting also.
I know when the fox visits. Foxes leave a faint skunk musk scent. Of course, the big dogs leave their big dog piles. But they have learned to not show themselves too often, after being shot at a time or two.