When she first visited in January, the phalluses were the size of rice grains. Now many of them are growing rapidly. The champion phallus from this Meller’s duck is a long, spiraling tentacle. Some ducks grow phalluses as long as their entire body. In the fall, the genitalia will disappear, only to reappear next spring.Link to NYT article. (thanks, Rose and Melissa)
The anatomy of ducks is especially bizarre considering that 97 percent of all bird species have no phallus at all. Most male birds just deliver their sperm through an opening. Dr. Brennan is investigating how this sexual wonder of the world came to be.
Part of the answer, she has discovered, has gone overlooked for decades. Male ducks may have such extreme genitals because the females do too. The birds are locked in an evolutionary struggle for reproductive success.