辨識
Large, hefty duck that has wild and domestic types. Wild birds are dark blackish overall with iridescent green and bronze, especially on the wings. Look for bold white wing patches in flight and red warts on the face (more extensive on males). Tends to be shy and most often seen in flight over extensive wetlands or along large rivers. Occurs extensively throughout Middle and South America, but typically scarce. Very restricted range in the U.S., only known from the Rio Grande Valley in Texas. Domestic birds, on the other hand, are regularly found walking around in parks and farms, looking for scraps of food and chasing native waterfowl. Plumage varies from all white to all black, typically with more extensive red warts on the face than wild birds. There is a well-established feral population in Florida, with smaller domestic populations spread across the globe.