Hi hi- I have two female ducks about 7.5 weeks old. One of them is making a high pitch quacking noise- sounds like a screech/ hiccup. I only found this clip: http://www.youtube.com/watch?v=eQikTmPNRFQ If you scroll to 1:40 that is the sound she makes. Since the title is "Asper Cough" I am worried it is aspergillosis. She does not look or act sick, she still quacks normally but she has been making this sound occasionally the past week. I am curious- Is this sound only in those with aspergillosis? Or is it normal for ducks to make this sound sometimes?