- Lake Duck
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Lake Duck 
Conservation status Scientific classification Kingdom: Animalia Phylum: Chordata Class: Aves Order: Anseriformes Family: Anatidae Subfamily: Oxyurinae Genus: Oxyura Species: O. vittata Binomial name Oxyura vittata
(Philippi, 1860)
Females
The Lake Duck (Oxyura vittata) is a small South American stiff-tailed duck. It is also called the or Argentine Blue-bill, Argentine Lake Duck, or Argentine Ruddy Duck.
The Lake Duck occurs in Argentina, Chile, Paraguay, and Brazil in southern South America.[1]
It is notable for possessing, in relation to body length, the longest penis of all vertebrates; the penis, which is coiled up in flaccid state, can reach about the same length as the animal itself when fully erect, but more commonly is about half the bird's length.[2][3] It is theorized that the remarkable size of the spiny penis with its bristled tip may have evolved in response to competitive pressure in these highly promiscuous birds, removing sperm from previous matings in the manner of a bottle brush.
Although most male birds have no penis,[4] ducks have a long corkscrew penis, and the females have a long corkscrew vagina, which spirals in the opposite direction.[5] The males often try to force copulation, but the complex mating geometry allows the females to retain control—most of the forced copulations do not result in successful fertilisation.[6]
References
- ^ a b BirdLife International (2009). "Oxyura vittata". IUCN Red List of Threatened Species. Version 2011.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/141430.
- ^ McCracken, Kevin G. (2000). "The 20-cm Spiny Penis of the Argentine Lake Duck (Oxyura vittata)" (PDF). The Auk 117 (3): 820–825. http://mercury.bio.uaf.edu/~kevin_mccracken/reprints/auk-117-820.pdf.
- ^ McCracken, Kevin G.; Wilson, Robert E.; McCracken, Pamela J.; Johnson, Kevin P. (2001). "Sexual selection: Are ducks impressed by drakes' display?" (PDF). Nature 413: 128. doi:10.1038/35093160. http://mercury.bio.uaf.edu/~kevin_mccracken/reprints/nature-413-128.pdf.
- ^ Found! The longest bird penis ever › News in Science (ABC Science)
- ^ Duck genitals locked in arms race | COSMOS magazine
- ^ Brennan, Patricia L. R.; Prum, Richard O.; McCracken, Kevin G.; Sorenson, Michael D.; Wilson, Robert E.; Birkhead, Tim R. (2 May 2007). "Coevolution of Male and Female Genital Morphology in Waterfowl". PLoS ONE 2 (5): e418. doi:10.1371/journal.pone.0000418.
External links
Media related to Oxyura vittata at Wikimedia Commons
Categories:- IUCN Red List least concern species
- Oxyurinae
- Birds of South America
- Birds of Argentina
- Birds of Brazil
- Birds of Chile
- Birds of Paraguay
- Birds of Uruguay
- Anseriformes stubs
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