Awesome! There's a PDF referenced in there too that seems to go into a lot more detail about plumage and molt (40+ pages!), which I will have to read a bit later.
I've been seeing mallard ducks during my daily walks and have really been enjoying learning about them. They're seasonally monogamous, and this was an entertaining read about their mating habits: https://www.tyrantfarms.com/duck-mating/