At least three times this week now, my rooster Charlie has herded or led all my hens out of their pen, scolding and snapping at any hen that goes back in. He's normally not aggressive towards the hens like this, so it's a bit odd. Today he went into the pen to scold a hen who had gone in to get a drink of water. When she ignored him, Charlie stopped for a moment and started looking frantically around the pen for a moment, then tried again. When the hen continued to ignore him, he left the pen, picked up a seed or something, and called her. She came to him, and he immediately scolded and growled and led her far away from the pen into the front yard. I thought that was rather unusual. None of my roosters have ever done that before. I thought that perhaps something might have attacked the hens in their pen recently, but I always keep a very close eye on my chickens, and nothing bad has ever happened to them inside their pen since before Charlie was even born. No one has gone missing or been injured, and alarm calls lately just turn out to be a couple hens squabbling over a preferred nesting spot. So it's pretty weird for Charlie to be on edge like this, especially towards the pen that he's lived around and in almost since the day he hatched. Any ideas?