Grebes Like Their Meals with a Side of Feathers—Here’s Why
Eating (and spitting up) their own plumes helps these diving birds to safely digest brine shrimp exoskeletons and other rigid foods.
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Transcript:
Some birds are just misunderstood and have been for centuries. Take the Eared Grebe, for example. The earliest description in the North American literature—dating from 1577 and based on Aztec observations—notes, “Its food is its feathers, only sometimes it eats fish.â€
Strange as it sounds, grebes do indeed eat their own feathers. Eared Grebes eat mainly brine shrimp and aquatic insects, which have rigid exoskeletons, making them both tough to digest and potentially damaging to the intestines.
So, grebes evolved to use their feathers as a way to slow down digestion. After the bird swallows them, the feathers enter a three-part stomach — first a storage chamber, then a gizzard, and lastly a pouch. The feathers form dense balls in both the gizzard and final pouch and appear to slow the passage of food long enough that the food can be safely liquified.
The tough bits are then regurgitated within a ball of feathers, much the way owls spit up pellets of bones from their prey. A grebe may pop out as many as six feather balls in an evening.
For BirdNote, I’m Michael Stein.
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Credits:
Written by: Bob Sundstrom
Narrator: Michael Stein
Senior Producer: John Kessler
Production Manager: Allison Wilson
Editor: Ashley Ahearn
Producer: Mark Bramhill
Associate Producer: Ellen Blackstone
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Eared Grebe call, ML106819, recorded by Randolph Little. ML133198 recorded by Gregory Budney.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2021 BirdNote January 2021
ID# grebe-01-2021-01-15 grebe-01