I don't think you'll starve percy by not flying youngsters, they are that good at what they do they will always find a meal, We are the odd-balls, we have flocks of birds flying out at this time of the year, it doesn't happen in nature only in the Winter months, easy pickings for them and what do we do, breed greater numbers, just perfect for them, reduce the numbers by half of youngsters and we'll still have some left at the end of the year but our losses will be reduced