Don't know if any of you all have seen this article but one of my favs on free ranging, has a lot of good points;
https://www.backyardchickens.com/articles/bees-key-points-to-successful-and-safe-free-ranging.65895/
I've lost some broody chicks to a skunk...that was a fun one to 'dissapear'.
I actually lost my last one been awhile to a fox in the coop at night just a few days ago. I never close coop door. Past few days it's shut and cement blocked both ways. Have a havaheart trap out for it and just right...
I loose one once in awhile but between pellet rifle and .22 the prob usually solved pretty quick. I've never came close to loosing every chicken I have. One or two maybe and some yrs none.