Scott noticed tonight that one of our ducks looked kind of like parts of her feathers have been chopped. She's fine, doesn't even seem to notice it, and she can still fly, but I'm not sure what could cause something like this. We of course checked the others after we saw this, but none of those look like this. I can't imagine what could cause this. Much of the chopping is so regular that it reminds me of something that's been cut with pinking shears. Any thoughts?