It's 2:30 AM and my hen mallard is floating in the pond quaking weirdly. We only have one drake and one hen. We've had them since June, they are around 16 weeks old. I went out in the yard by the pond to see what was going on. All I found was both ducks floating side by side in our small bond and the female letting out a series of quacks. Not excited quacks, just a steady string of 4 to 6 quacks with about a 30 to 60 second pause between series, like quack, quack, quack, quack, long pause, quack, quack, quack, quack, quack, quack. They weren't that loud either. I walked around thinking maybe another animal was in the yard but nothing. We live in the city and have a high fence around the yard. Any thoughts? We are new to raising ducks and this is a first. Thanks. P.S. Just checked again, it's been about 30 minutes. She has slowed down to intermittent single quacks.