I'm a new muscovy owner and would like help understanding the noises my birds are making. They're 4 months old. The duck trills very softly; usually she's backing away from a human observer. So is that a sound of distress? The drake opens his bill and pants quietly, also while backing away from a human observer. Sounds like he's practicing his lamaze breathing? He does not seem aggressive at all; maybe alarmed? What other sounds can muscovies make and what do they mean? Thanks!