A musk duck from Australia was rumored to have used some salty language in a recording from 1987. Animal behaviorist Carel ten Cate of the University of Leiden told Reuters, “I thought 'This must be a hoax.’” But when he heard the recording, the Dutch scientist said he was convinced. "It's definitely based on the human voice,” he said. While parrots, hummingbirds and songbirds are known to mimic human vocalization, ducks aren’t. “That's quite extraordinary,” ten Cate said.