Wilson’s Phalarope

During spring migration, Wilson’s phalarope can be found in groups in small ponds and wetlands in the plains. The birds are often seen spinning in the water as if one of their paddling legs was broken. The spinning is purposeful, as it is a way for the birds to concentrate aquatic insects and forage more efficiently. However, there is more to know about phalaropes than their funky spinning behavior! Wilson’s phalarope is one of the few species in which the traditional male and female roles are switched. The females lay eggs for at least one male and then disappear while the males guard and incubate each nest for her. This mating system is called polyandry, Greek for “many men,” the opposite of polygyny, “many women.” A careful observer will notice that the female phalarope is more colorful than the male—again, the opposite coloration pattern of most bird species. What are the advantages of this mating system? Sitting on a nest is dangerous business with predators lurking in the landscape, and it is energetically demanding to produce eggs and care for young. The female phalarope spreads her risk among many nests. She spends energy on eggs, while the males spend their energy caring for the nests and young. The males do not need to be colorful as they are not competing for females.