I love hawks and Red Tail are ubiquitous in most parts of the country. Sacramento is no exception. We have one that is often in the redwood tree next door, and I see falcons pretty regularly, too. It's the reason I'm not real gung ho about free ranging and will be building a portable tractor in addition to having a permanent run. Our run is covered with plastic corrugated panels that can be removed for a sun roof, but they're still protected by hardware cloth.
Some people feel that losing a bird or two is just the price you pay for free ranging, but with only three hens max allowed in my city, that's too big a price. When my summer veggies are spent, I think I'll put deer netting over my garden, which is fenced to keep the dogs out, and let the girls go at it.
I don't trust my big dogs with the hens, either, or else they'd be good protection. Our Pit Bull is getting better at learning "leave it" but I wouldn't want him around them without supervision. Our German Shepherd mix, however is waaay to interested. She's always had a strong prey drive, too, and is a terrific rat and squirrel hunter, so she could easily get a chicken. Our little Chiweenie, though, has been pretty good around them so far. He has a deformed jaw, too, so he couldn't hurt them if he wanted to. He's not a yapper, but he is quick to bark at critters that come in our yard, so he might a good little guard dog for the hens, with his bark if not his bite.