It shouldn't be too hard to keep a small flock of backyard chickens. So when we built our coop-area, we though mainly about protecting them from the weather and things like neighborhood cats and dogs.
There's a threat from above even here in downtown New Jersey. Chicken Hawks (or as my son corrects me; Red-Tailed Hawks) circle above, and boy do they like chicken. So after learning the hard way and loosing a hen, we strung up pond-netting to protect our flock.
Now I see hawks all the time - because I'm watching. Start watching! You'll see things you never imagined were there.