What function do intentionally swallowed feathers serve in the Eared Grebe's digestive system?

Answer

They act as gastric ballast or a buffer against sharp food remains

The swallowed feathers interweave in the gizzard, forming a soft, protective mat that cushions the stomach lining against sharp components like chitin exoskeletons and shell fragments.

What function do intentionally swallowed feathers serve in the Eared Grebe's digestive system?
fooddietbirdanimalGrebe