I just noticed this today, but husband says he's seen it other times - our Ancona rooster, when he's standing out in the yard or on a roost and crows, sometimes his legs collapse under him and he suddenly sits down. It seems like a planned sit down, not a fall over. Is this normal? No other rooster we have does this? Could it be a sign of illness? He is only 6 months old. He eats well, walks around fine other wise, and didn't have this issue even a month ago. He is in with other roosters, no hens. He does seem to put a whole lot more effort into crowing - really puts his body into it - than the other roosters do, however.