Eating Feathers
photograph of a Pied-billed Grebe by Rohan Kamath	Perhaps because the idea of swallowing hair is so unpleasant to us, it is difficult to believe the stories of birds deliberately eating their feathers. Nonetheless, some do and they do so regularly. Grebes, for example, consume their feathers by the hundreds. Feathers taken from parents are found in the stomachs of chicks only a few days old. Fifty percent of the stomach contents of a Horned or Pied-billed Grebe may be feathers. This odd behavior seems to have a purpose. The action of the gizzard in these primarily fish-eating birds is insufficient to crush the bones that are swallowed. The feather balls are thought to protect the stomach by padding the sharp fish bones and slowing down the process of digestion so that the
bones dissolve rather than pass into the intestine. This notion is supported by the observation that the Least Grebe, which of all the grebes consumes the fewest fish, also accumulates the smallest feather ball. Comparative studies of the gizzards and digestive physiology of fish-eating birds are needed to test this hypothesis. If it is supported, the question will then be why grebes have not evolved digestive tracts that can function efficiently without being stuffed with feathers.
SEE: Feathered Nests. Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.