Anas platyrhynchos, the mallard duck, is the wild ancestor of domestic ducks. They reach an adult size of up to 28 inches and 3 pounds. This migratory water fowl has worldwide distribution. Though protected in some states, mallards are widely hunted and are common visitors to all types of freshwater habitats. Mallards are kept by some poultry fanciers as barnyard fowl. How long it takes mallards to mature depends on how you define "mature."
Baby ducks hatch after a 26- to 30-day incubation in their eggs by their mother. The ducklings enter water before they've turned 24 hours old. They stick close to Mama for several months, while she keeps her babies warm and protected in their nest at night and leads them to food during the day. Ducklings lose their baby down and grow their adult feathers by around day 45, and they are able to fly at around 60 days of age.
Though mallards can take flight anytime between days 45 and 60, they don't become fully independent of their mothers until around 70 days of age. At this point they're able to find food on their own, hide from predators and maintain their body heat throughout the night. They begin to disperse to their own feeding and sleeping areas and may migrate to winter foraging and breeding grounds at this time.
If you define maturity as sexual maturity, however, mallards don't mature until a bit past their first birthday. Mallards attempt to breed for the first time in the late winter to early spring following their birth, or at approximately 14 months of age. Young adult females who've bred establish nesting sites in the spring. Once they've successfully reared a batch of babies, they tend to use the same site year after year.
It takes a while for males to obtain their distinctive green-headed coloration, and they don't keep it year-round. Males only wear their bright colors for the breeding season. The rest of the time they sport "eclipse coloration" -- mottled brown feathers similar to the female's and much easier to hide from potential predators. Around the time Mama's hatching her eggs, he's losing his breeding feathers. He won't wear them again until after he molts in the late summer to late fall. Once he's changed into his breeding colors, he'll court females until he finds one special lady duck. He'll stay with his lady long enough to establish a nesting site, then fly the coop when she begins to lay eggs.