In the wild Mallard Drakes eclipse molt. This is when the molt “eclipses” their usual bright plumage and occurs shortly after nesting during spring, and takes about 3-5 weeks to complete.
During the eclipse molt, drakes (male ducks) lose their brightly colored “nuptial” feathers in exchange for basic/eclipse plumage. They also lose their curly drake feather on the top of their tail, which the females find oh-so attractive.
Drakes are unable to fly during this time since they lose all of their flight feathers via a “simultaneous wing molt,” a process unique to waterfowl since they’re able to survive without flying for extended periods, unlike most other birds.
This process ultimately renders drakes rather drab-colored since they’re no longer trying to attract a mate. No more bright green head! Instead, their eclipse plumage serves as camouflage to make them harder for predators to spot.
Mallard hens (female ducks) experience a similar molt several weeks AFTER their ducklings have hatched.
In late summer-early fall, Mallards undergo their nuptial molt. During the nuptial molt, only the body feathers are shed. This is when the drakes get their attractive bright feather color back so the females can better decide whether they’ll make a worthwhile mate.
~ Tryant Farms