For the last few weeks, I've been free-ranging our 12 chickens, (four older girls who are 22-weeks and 10 18-week olds, including two cockerals) and things had been going great. I started letting them out about an hour before dusk and had been gradually increasing the time that they were running around. They loved it and all came back to the coop on their own without any issues at all. At first, I was out there with them - practically on top of them - the whole time, but lately I'd been doing stuff in the front of the house, going in for a minute, hanging out in the pool, etc. while they were out. I would check on them a LOT though, even if I wasn't hovering, but I gotta admit, it would sometimes be 10 minutes between checks. Last night, I checked on them and they were all around the back of the screened in pool area (we had just weed-whacked and they were THRILLED with the grass, bugs, etc.) and when I went out about 10 minutes later, Maple, our SLW (and only egg layer!) was missing. One of the young roosters was calling and calling for her but then ushered the rest of the younger girls back in the coop. Maple's "sisters," the three feedstore chicks that I bought with her, didn't go in right away with the others, and one of them, Miss Kitty, was distraught and would NOT go back in the coop at all. I finally had to pick her up and physically place her in the coop. We searched our property - we have almost 3 acres in a pretty wooded area in a neighborhood where everyone has giant acre-plus sized lots (and there are a LOT of chickens in backyards out here), but although we think we heard her, we didn't find her. I thought for sure she'd be home by this morning, but she's not. We searched again after church and ran into our neighbors, who are veteran chicken people, and they said she's probably gone if she stayed out overnight - they free range all day and lose a few to hawks, owls and the occasional bobcat. I've never seen evidence of anything trying to get into the coop or the run, but I guess that's a good thing. Anyways, I don't think I will let anyone out of the run anymore; I know they love it, but I'm just sick about losing one. I suppose it's all a part of chicken ownership, but it still sucks.