I am new to ducks, I just got mine less than two weeks ago, and they are all from different hatchings, so they are different ages. My oldest one is about 6 weeks old, and she has been making some weird noises. She is starting to get her "big girl" voice. Now, though, when she is resting she makes this weird honk-hum noise. It is hard to describe, but it sounds like she is snoring, only she is wide awake. She ONLY does it when she is relaxed and sitting. If she is up and walking around or eating, she doesn't do it. Is this normal? Should I be concerned? None of my other ducks are doing it, so far anyway.