Mallard (female)

If someone at a park is feeding bread to ducks, chances are there are Mallards in the fray. Perhaps the most familiar of all ducks, Mallards occur throughout North America and Eurasia in ponds and parks as well as wilder wetlands and estuaries. The male’s gleaming green head, gray flanks, and black tail-curl arguably make it the most easily identified duck. Mallards have long been hunted for the table, and almost all domestic ducks come from this species.

http://www.allaboutbirds.org/guide/mallard/id