About Tachyeres pteneres (J.R.Forster, 1844)
Tachyeres pteneres, commonly known as the Fuegian steamer duck, is the largest species among steamer ducks. This is a very heavily built waterfowl, with a body mass ranging from 3.5 to 7 kg (7.7 to 15.4 lb) and a total length ranging from 65 to 84 cm (26 to 33 in). Males are noticeably larger than females: the average body mass of males is 5.34 kg (11.8 lb), while females have an average body mass of around 4.2 kg (9.3 lb). The wingspan of this species ranges from 85 to 110 cm (33 to 43 in), but the wings are too small to enable the birds to fly. Instead, this species uses its wings like paddles to help it skim rapidly across the surface of the water. This species is heavier than any other wild bird that is called a "duck", and has approximately the same body mass as the largest wild geese in the world. It should be noted that this species is only distantly related to most true ducks, such as those in the genus Anas. Adult males have blue-gray heads and necks, with paler coloration on the crown and forehead. Males have a narrow white eye-ring that extends backward as a stripe, and a reddish-brown throat. The abdomen, ventral area and undertail coverts of males are white, and the tail is grey. Adult females have darker gray-brown heads and dark reddish throats. Females share the same body and wing coloration as males, but may have brown or wine-colored tint on their feathers. Juvenile Tachyeres pteneres are similar in appearance to adult females, but have slightly duller coloration.
