Today I was sitting out in the new chicken yard with the big girls and we heard a hawk. I scanned the sky and didn't see it, then I looked at them. A couple of them had frozen, and then Jane (Orpington) did the warning call. The first and only time I have heard one of my girls do it was in the run and it sounded like she was muttering to the others. I looked at them (had been looking away, cleaning the poop shelf) and they were all frozen. I looked outside the run and we all watched in horror as a snake slithered by, stopping every 30 seconds to try and find a way in. I only know now what it is because I had just watched a BY Bob video of all of you and your chickens hiding under the coop while the Cooper's hawk was outside. Hattie did the warning call, which you called a "growl."
It was fascinating to see that my chicken who has spent the whole 15 months of her life living in a brooder inside and then a confined run knew to do that.
And that's why I'm trying to read the old posts. So much to learn!