If you are worried about animals getting to them, then maybe you should follow the advice of letting them out for like an hour before dark if you are out there with them. That way they will go in at dark and you wont have to worry about rounding them up if you need to leave for some reason. They wont have time to leave the yard because they wont get a chance to wander too far before it gets dark.
Good suggestion. I leave mine out in the morning if I know I am not going any where and they are out all day. In the past six years I have lost approximately a dozen to hawks (even my fave - Ugly), another half a dozen to coyotes and just as many to raccoons. I loved them all since I incubated them in my incubator in the bathtub, brooded all of them in my living room. But, they are just so happy free-ranging and when I don't let them out they are really upset and bawking profusely, so I justify letting them out with the chance of them getting taken because they are just so contented to be out, I could not deprive them. I appreciate them immensely and if something happens, I know that it is all part of letting them free-range.