SE15 was developmentally impaired by the foot and beak disease, allowing the younger sib to quickly become stronger and dominant. But 16 didn't prevent 15 from surviving to fledging age when he/she could probably easily have done so. I don't think WBSE's are any more likely to exhibit siblicide than BE's are. This year, too, I'm wondering if 22 has other health problems besides not getting enough food. He's always seemed kind of weak and unable to remain sitting or jostle for position with 21 without falling down. He goes face down a lot without any help from 21.