I live on the lake and witnessed this behavior. There were several female ducks with babies. Everything was peaceful. Then, out of nowhere, a mallard attacked one of the females and started drowning her. She was screaming, babies were screaming, and i was throwing rocks at him, lol. Eventually, he let go and left. But the most amazing part of the story was that one of the other mothers came over and got the scared bsbies and took them to safety. When the assaulted female duck recovered and could breathe again, she came and got her babies. 😊