White-headed Duck
Oxyura leucocephala

see larger image White-headed Duck (male) Oxyura leucocephala Fort Worth Zoo - Fort Worth, TX © 2008 Jeff Whitlock see larger image White-headed Duck (female) Oxyura leucocephala Fort Worth Zoo - Fort Worth, TX © 2008 Jeff Whitlock see larger image White-headed Duck (male) Oxyura leucocephala Fort Worth Zoo - Fort Worth, TX © 2008 Jeff Whitlock see larger image White-headed Duck (male) Oxyura leucocephala Fort Worth Zoo - Fort Worth, TX © 2008 Jeff Whitlock

Related Links
Flickr - may have photos
Wikipedia - may have a species page