Stiff-tailed ducks
Male White-headed Duck, Oxyura leucocephala
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Subclass:	Neornithes
Infraclass:	Galloanserae
Order:	Anseriformes
Family:	Anatidae
Subfamily:	Oxyurinae
Genus:	Oxyura Bonaparte, 1828
Species
Oxyura australis Oxyura jamaicensis Oxyura leucocephala Oxyura maccoa Oxyura vittata and see text

The stiff-tailed ducks are part of the Oxyurinae subfamily of ducks. All have, as their name implies, long stiff tail feathers, which are erected when the bird is at rest. All have relatively large swollen bills.

These are freshwater diving ducks. Their legs are set far back, making them awkward on land, so they rarely leave the water.

Their unusual displays involve drumming noises from inflatable throat-sacs, head throwing, and erecting short crests.

Plumage sequences are complicated, and aging difficult.

[edit] Species

• Blue-billed Duck, Oxyura australis
• New Zealand Stiff-tailed Duck, Oxyura vantetsi (prehistoric)
• Ruddy Duck, Oxyura jamaicensis
• White-headed Duck, Oxyura leucocephala
• Maccoa Duck, Oxyura maccoa
• Argentine Blue-bill, Oxyura vittata - notable for possessing the longest penis of all vertebrates in relation to body length.^[1]

A fossil species from the Late Pliocene or Early Pleistocene of Jalisco (Mexico) was described as Oxyura zapatanima. It resembled a small Ruddy Duck or, even more, Argentine Blue-bill. A larger Middle Pleistocene fossil form from the southwestern USA was described as Oxyura bessomi; it was probably quite close to the Ruddy Duck.

"Oxura" doksana from the Early Miocene of Dolnice (Czech Republic) cannot be assigned to any anatine subfamily with certainty.^[2]

[edit] Footnotes

[edit] References

• Worthy, Trevor H.; Tennyson, A.J.D.; Jones, C.; McNamara, J.A. & Douglas, B.J. (2007): Miocene waterfowl and other birds from central Otago, New Zealand. J. Syst. Palaeontol. 5(1): 1-39. doi:10.1017/S1477201906001957 (HTML abstract)