One of my Swedish ducklings has a spot right in the middle of her chest where you can see it sucking in and then comes back out when she's standing up nice and tall peeking at me. It almost seams like it's happening with each breathe but she moves so much i can't tell and when i hold her you can't see it at all. None of the others do this. She seams fine otherwise. Just wondering if anyone might know what is going on? I can't find anything in my books and this is my first batch of ducks so i'm pretty much clueless. Thanks!