Waterfowl (Anseriformes) are a group of birds that include screamers, ducks, geese, and swans. There are about 150 species of waterfowl alive today. Waterfowl are so named for their preference for aquatic habitats. Most species live close to freshwater habitats such as lakes, streams or ponds but some species also inhabit marine environments during the non-breeding season. Waterfowl are medium to large size birds. Their plumage may include subtle variations of gray, brow, black or white. Some waterfowl (notably the screamers) have ornamental feathers on their head and neck while others have brightly colored patches on their secondary feathers (such as blue, green, or copper). The plumage of young waterfowl is often duller than that of adults. Waterfowl have webbed feet, an adaptation for their aquatic lifestyle which enables them to swim with great efficiency. Waterfowl are often prey for a variety of predator species including humans, red foxes, coyotes, raccoons and striped skunks. Occasionally, waterfowl may also fall prey to other birds such as American crows, black-billed magpies and owls. There are three groups of waterfowl, the Anhimidae (screamers), the Anseranatidae (magpie goose) and the Anatidae (geese, swans and ducks).
Anseriformes are well known for the ease at which they can become domesticated. The mallard was first domesticated nearly 2000 years ago, the eastern greylag goose almost 4000 years ago. Various breeds of these species are commonly found on farms today. Anseriformes often make their nests near the water's edge, although whistling ducks nest in trees and the torrent duck nests in holes in the riverbank. Screamers nest offshore in shallow water. Most Anseriformes are solitary nesters, but the eider duck nests in large colonies. Most Anseriformes are herbivorous in nature, feeding on water plants, although some species, like the screamers, will eat insects.