We're in the country, on 173 acres, sharing it with native predators of many types. My girls free range during the day in and around the barn, which provides lots of protection from the elements and aerial predators. I put my hens to bed in their runs each night, and let them out each morning. Barn and 3 acres are surrounded by 5' no-climb horse fence, with a field fence apron along much of the bottom, and either electric tape or wire running on top and bottom of fence. Due diligence is required to keep apron intact (mostly armadillo excavation

) and fencing charged appropriately.
The next best predator-deterrent (note: not necessarily predator-PROOF) feature, aside from the fencing, is ample cover for hens to hide in or escape to. Flat-bed trailer parked under the trees (I dump water under it during summer--co-o-o-o-ol!), a variety of many native perennial bushes (now in spectacular bloom!) near the barn, A-frame shelters (made from a single wooden pallet) strategically located throughout barnyard, large oak trees whose limbs have been allowed to naturally and gracefully grow down to the ground (no 'lollipop' trees here).
Foxes are numerous, mostly passing by the barnyard on their way to eat sunflower seeds billed out from our hanging bird feeders--their preferred choice of protein. Coopers and small raptors, right now, are busy chasing doves, but this is raptor migration season, too. Raccoons are busy meddling in our Frog Pond near the house at night. We have no dogs, no roosters, no guineas, no donks or llamas; just my elderly retired gelding and my hens.
Just painting a picture here of our setup, like others have posted. Good suggestions from folks on (1) ample, natural cover (2) electric chicken fencing (3) and don't leave foodstuffs out to attract predators (including cat food).