Like other grebes, the red-necked grebe ingests large quantities of its own feathers, which remain in the bird's stomach. Feathers are not only swallowed by adults, mainly during self-preening, but are often fed to the young, sometimes within a day of hatching. These feathers soon decompose into a felt-like, amorphous mass. The function of the feathers in the stomach is unknown, although it has been suggested that they help to protect the lower digestive tract from bones and other hard, indigestible material.