Wednesday, May 29, 2013

Wilson’s Phalarope

These five photographs, taken in May 2013, are a series of a male Wilson’s Phalarope. The photos are of the same bird near Leola, South Dakota. I have discussed sex role reversal shown in phalaropes in a previous post. (Females are more brightly colored than males and it is the male that tends the nests.)

Phalaropes are famous for their feeding behavior. They spin in tight circles “in a manner reminiscent of a slightly demented toy” (Rubega et al. 2000). The spinning may stir up prey from the bottom of shallow water. Other researchers hypothesize that the spinning stimulates prey immobilized in cold water. This circling creates upwelling of water that brings the phalarope’s prey up to them. This flow can be created in water with depths of up to a half-meter, thus allowing phalaropes to spin in relatively deep water.

Other research suggests that phalaropes spin only in one direction—individuals may be left or right spinners. In any case, the phalarope moves with each spin, so that the bird slowly moves across the water. As the bird does so, it inspects the surface for new prey items. Most of my information on spinning phalaropes is taken from Rubega et al. (2000). Although famous for their spinning, phalaropes often feed like more typical sandpipers, probing muddy shores for arthropods. 

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