My 2 runner drakes are constantly in the water & constantly preening, the past 2 morning when I've gone to let them out, there has been feathers everywhere & I can see the skin on the chest/breast area. They are both 9/10 weeks old. Is this normal? They have a female with them & all get on great. Just find it bizarre as my female isn't losing/pulling feathers. I'm new to ducks so any advice is great! Thanks!