We have a large black crow who lives in our yard. I'd stand out and watch it warily whenever we'd let the girls out of the run and into the fenced yard. Then I started really observing it. I was nervous, because all six of our pullets are still fairly young. But he'd just sit there and watch them, maybe looking for leftover feed. Then another bird would land nearby and he'd swoop down and drive them off. He acted like a sentry for any critter that happened to come within 50 yards. At one point HE landed near our big pullet in charge and she ran him off quickly. Our run is covered with a clear plastic roof and he likes to sit up there. He doesn't try to access the run. I really do think he's just adjusted to his job as guardian. We feed him our too-ripe or compromised tomatoes off the vine and he seems to appreciate it. He comes very close to us and I guess someone else must feed him. It's just nice to have somebody looking out for the chickens since our dog is too dumb. I know birds can carry diseases, but he can't access the coop, run, or feed. He's a big guy. From a distance I can barely tell him apart from our Black Spanish eight week-olds.