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Bird's Biggest Secret
The Argentine lake duck has the longest penis relative to body size of any bird — up to 17 inches, longer than the duck itself.
Argentine Lake Duck
Oxyura vittata
This small South American duck holds a remarkable record among birds for its reproductive anatomy.
Vital Stats
🏷️ TypeStiff-tailed duck (waterfowl)
🌍 Found InLakes and marshes of Argentina and Chile
📏 Size35-46cm, ~600g
⏳ Lifespan10-15 years
💕 Mating SystemPromiscuous — intense sperm competition
📅 Mating SeasonSpring (September-November in Southern Hemisphere)
👶 Offspring5-8 eggs per clutch
🍆 Penis Size42.5 cm
⏱️ Sex Duration3 seconds
🔬 Notable AnatomyLongest bird penis at 42.5cm — same length as the duck's body; corkscrew-shaped
⚖️ Sexual DimorphismMales have bright blue bills during breeding; larger than females