What is the recognized primary physiological function of feather ingestion in grebes?

Answer

Acting as a protective lining within the stomach cushioning the digestive tract

One key theory suggests that the mass of ingested feathers acts as a protective lining within the stomach, cushioning the digestive tract from sharp components found in their prey, such as exoskeletons or fish bones.

What is the recognized primary physiological function of feather ingestion in grebes?
foodbirdanimalGrebe