The mallard is the ancestor of most domestic ducks, and intermixing between some species is common in park ponds.

Adult ducks molt all their flight feathers simultaneously and replace them before fall migration. This simultaneous molting of flight feathers is called an eclipse. During this time, the duck are very shy and vulnerable. In most species, males go through the eclipse first while females stay in the nest. Males will gather in a safe area to molt during which time, they wear a dull plumage. When alarmed, they dive or paddle away.