As 7L Farm mentions, in some areas it is the heat that bad, and chickens can and do succumb to the heat. even healthy chickens (and other animals, as well). We have the samedown here in SE Texas. I've found "double shade" almost essential in our summers if you don't want to lose birds. By "double shade", I mean not situating chicken coops and hen houses our in the open sun. The metal roofs most of us use become radiant heating elements that can just cook animals inside. Try to situation under shade trees. Build all coops or barns tall, with high roof clearance, both the get that hot metal roof further away fromthe animals,and allow maximum ventilation.
Breed selection for extreme heat can be as important as breed selection for extreme cold. Generally lighter built chickens (and other specie animals) handle extreme heat better. In chickens, heavy plumage isn't best in hot climates...I'd not even THINK of having Buff Orpingtons here! The worst for heat are heavy, heavy birds, giant breeds. I once raised a bunch of CornishXRocks side by side with White Rocks, purchased at the same time,and it was getting on into early summer. In addition to the leg problems on the CornishXRocks, they weren't far from size to process the broilers when we had an early high heat spell, not unusual here, and lost a good many of those CornishXRocls....despite double shade and when I realized they were getting in real trouble, even fans, but none of the White Rocks.
Back to cover for hiding from hawks, as others noted, they don't have to be fancy or elaborate, and the birds prefer open sides. Even bushes,andlawn furniture work. I never really had problems with hawks, but thinking back, that may have also been part of why. Did have a lot of bushes, small to large trees and such, as well as an assortment of other cover-providing objects and features where my chickens had range. Things like rabbit hitches, tractor and implements, farm trailers, as well as lawnchairs, benches, tables, work benches, in various areas for sitting while doing whatever around the place.