Scientists say male ducks compare their penises — and grow them bigger

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Once in a while, we like to divert your attention to some relatively useless but nonetheless interesting information from the annals of science. Today’s bit of hijacked knowledge comes to us from a Science News story on ducks.

Ducks apparently regrow their penises after eating mating season wraps up, putting away the peter and moving on to more important things like… waddling. According to new research, a drake’s dong grows back at a varying rate compared to how much surrounding competition there is. Their penises can end up being much bigger the next time around.

Says Patricia Brennan from Yale: "Among lesser scaup and ruddy ducks, the regrowth varies in length or timing depending on whether males have to compete with a bunch of other guys."

Duck penises can grow up to 25cm, which is

more than half its body length. That extra length may give a male a competitive advantage in delivering sperm when females have multiple mates.

To see whether competition among males influences penis growth, Brennan housed some of her drakes in groups of seven to eight males with just five or six females. Other males lived with just one female.

Among the scaup, males competing in groups grew penises 15 percent longer, and sometimes up to 25 percent longer, than drakes with no mating rivals…

Via Science News.