I like mine to get out and peck about, but the chance of loss is real. I live in a rural ranch and have all the predators except a neighbor's dog.
These are the tricks I use to reduce the loss:
In the free range space, there needs to be natural cover, such as bushes or man made cover such as pallets up on block. Prey need to be able to hide. Some chicken feathers blend in much better to the surroundings than others. Currently I am breeding for this, matching the SD prairie.
A rooster that is over a year old. When you walk within sight of your set up, the rooster should be the first one to see you. If not, you need a different rooster. He needs to be more than a year old, as younger roosters are only thinking of one thing, and have no idea of true flock duties.
Do not let your birds out on a schedule, let them out early some days, late others. Some days not at all.
Do not let them out if it is a real dark cloudy day, or a day of high wind, both will give advantage to the predators.
If you or rather when you get hit, Leave everything in lock up for several days or even weeks. Eventually your predators will move on if the tasty, fast and easy food is locked up.
Train your birds to come to a can of feed shaken, so that you can round them up and lock them up quickly and easily.
Edited by Mrs. K - 2/27/16 at 9:30am