We observed a few days ago a strange display by a blackbird. We have an arbour a few yards from the kitchen window and a male blackbird came and stood on one corner. A few seconds later another male stood on another corner. Nothing odd there, but instead of the usual noisy fracas, the first bird lowered its head opened its beak slightly and proceeded to sway its head from side to side five or six times, much like an avocet does when feeding. Another male arrived on another corner and the first bird did this action again, all three stood in silence until a female arrived and spoiled things. bird one followed by bird two, then three, and finally the female flew off in silence. It looked like a submission display to us. Anyone seen this behaviour before?