NOEL KING, HOST:

Good morning. I'm Noel King. Unlike parrots, ducks are not known for imitating human sounds. But a researcher recently found a decades-old recording of an Australian musk duck named Ripper who is saying what sounds like, you bloody fool.

(SOUNDBITE OF ARCHIVED RECORDING)

RIPPER: You bloody fool.

CAREL TEN CATE: Vocal learning is a very rare trait in the animal kingdom.

KING: Researcher Carel ten Cate says finding it in a duck is really special. But who made Ripper mad? It's MORNING EDITION. Transcript provided by NPR, Copyright NPR.