Mallard — Length: 23 inches, Wing span: 35 inches
Because of its abundance and near-total occupation of North America, the Mallard is often considered the standard duck against which all others are compared. Most domestic duck strains are derived from Mallards, and interbreeding with these strains results in feral populations inhabiting urban and rural ponds in many places.
Mallards go through a number of courtship rituals when pairing up in winter for the coming nesting season, but once nesting is over, they are quite gregarious for the remainder of the year. More than a half-dozen other species of ducks have been known to lay eggs in Mallard nests.
Notice the color of the bill on the two female Mallards above and the one below. The amount of black on the bill is variable.
This photograph has 3 Mallards with their heads up and 2 shovelers with their heads down. The rusty sides of the male Northern Shoveler make it a fairly obvious I.D. The female shoveler is headed in the opposite direction. It is very similar to the female Mallard on the left but notice slightly redder hue to the side of the duck. Also notice the broad, pale edges to the feathers on both females.