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.