A couple things to consider for you new free ranging folks... One was just touched on, is the age of the flock, If you have all youngsters they are much more vulnerable being inexperienced. The other thing is the color. I know I didn't think of that when I added a8 1-2mo old chicks. I not only raise chickens for a colorful egg basket but also their feather color. I wanted some white chicks. I had four white chicks in the temporary housing I was using while in quarantine/introducing them to my current flock. I let them out during the day while I was home. In one day I lost two and lost a third by the end of the week. There were no remains or anything, not even any proof I even had them to begin with. It didn't dawn on me until after the third that it was just the white ones going missing. Duh, the rest were all camouflaged. The white ones may have been wearing big neon signs saying "free meal right here, come and get it!" Even with the realization and being more cautious with the remaining white chick, I still lost it within a month. They would have fared much better if they had an adult with them as I had seen one of my EE Mommas fight off a hawk going after her own babies during that same time period.