Male Mallards (as in top picture) have a dark, iridescent-green head and bright yellow bill. The gray body is sandwiched between a brown breast and black rear. Females and juveniles are mottled brown with orange-and-brown bills. Both sexes have a white-bordered, blue “speculum” patch in the wing.
Mallards are “dabbling ducks”—they feed in the water by tipping forward and grazing on underwater plants. They almost never dive. They can be very tame ducks especially in city ponds, and often group together with other Mallards and other species of dabbling ducks.
Mallards can live in almost any wetland habitat, natural or artificial. They are monogamous and paired for life but the male do have "extra marital affairs" lol. Look for them on lakes, ponds, marshes, rivers, and coastal habitats, as well as city and suburban parks and residential backyards.