We see hawks and eagles picking up mice and rabbits from a field out back. Really worries me when it's time to put my chickens outside.
I've had between 3 to 5 backyard hens at a time over the last seven years. We have a smaller cottage backyard and found it easy to put up a pop-up canopy, 5 large doghouses picked up on trash days or in thrift stores, plastic lawn furniture and tables, tall trash bins, a compost recycle bin, potted plants, rose bushes, and rosemary plants for our hens to hide/snooze under. For a large open area I would suggest you get generous with a lot of scattered lawn furniture, benches, low lean-to's, several recycled doghouses and plant some inexpensive rose bushes around the open field areas -- all to give hens a lot of places to dash under if a hawk flies overhead. The hawks want a nice flying start in an open yard to chase after running hens.
The less open area for hens to run around, the safer it is. Again, not always a 100% guarantee that a hen is completely safe but the smart hens know how to hide and hawks don't seem to want to engage in battle on the soil -- they prefer a flying aerial catch using their talons. Obstruct open flying spaces with bushes, lawn furniture, dog houses, canopies, low lean-to shelters, etc etc to give the hens their best chance for survival.
A pop-up canopy is nice for shade. We bury our canopy legs about 6 inches into the ground so it doesn't parasail away in the breeze.
I've had free-range backyard hens for 7 years including Silkies that can't fly and none have been taken by our Cooper's Hawks that sit on our fence or lawn furniture to watch our girls. None of the hawks have ever engaged in ground battle with our hiding hens even if they can see them 5 feet away! The hawks will sit on our house or patio roofs or sit on the lawn furniture or backyard fence and stare at the hiding hens but never have engaged in battle with them. We had one stupid hawk, probably a young one, that flew into our coop kennel wall and knocked itself out while our hens were hiding down below. As long as there are rats, mice, or bunnies around, there's no way to keep hawks away. We live near a freeway where there's a lot of trees and foliage for the Cooper's Hawks to nest in and raise their offspring with a lot of rodents for them to catch as food. There's no way we can keep those hawks from eyeing our hens too but our girls have been safe to evade captures.
In the past we've used leftover plywood planks and cinderblocks to raise the wood about 1-1/2 feet above the ground so the hens can hide underneath. On trash days we always watch lawn trash to see if we can recycle anything from people's lawns like old doghouses, wood planks, we once rescued a wood headboard and made a lean-to out of it. Our contractors left a couple long scaffolding planks while remodeling our house so we set the planks on cinder blocks for the hens to hide under. We got very creative once we got hens LOL!
