I've been wondering for awhile about this strange thing two of my hens do. I will hear this sound that seems similar to maybe the sound of a chicken in absolute agony, and I will rush out to check on them, and they seem completely fine and proper. Then, after watching them for awhile, one will stand up, stretch out her neck, flap her wings furiously, and with the expression of utter madness in her eyes and her beak wide let out a gargling and horrific scream as though she's being stabbed, strangled, etcétera. Then everything will return to normal. The other hens don't even seem to mind the strange behavior at all. There doesn't seem to be a cause for this, like a crow flying over or any threat. Is it another one of those normal, weird chicken things?