(CNN)An Australian musk duck has been recorded saying "You bloody fool" in the first documented instance of the species mimicking human speech.
A hand-reared male named Ripper was recorded imitating the phrase during a courtship display, according to a study published Monday. The authors said he could have learned it from his caretaker.
"The Australian musk duck demonstrates an unexpected and impressive ability for vocal learning," the study said. The report also details how Ripper imitated the sound of a door opening and closing.
There are many species of ducks and geese that are bred in captivity, and there haven't been any reports of them showing an ability to mimic human sounds, study author Carel ten Cate told CNN on Tuesday.
"It's quite exceptional then to come across a species which apparently has the ability to mimic these sounds," he said.
Songbirds, parrots and hummingbirds are known to exhibit this vocal learning ability, but this is the first fully documented instance of musk ducks exhibiting vocal learning, said ten Cate, a researcher and professor of animal behavior at the Institute of Biology Leiden, at Leiden University, the Netherlands.
"It's not exactly a human voice, but very voice like," he said. "It's mimicking quite well."
Some species are better mimics than musk ducks, but there are many songbirds and parrots that are worse at copying, added ten Cate.
Ripper was hand-reared at Tidbinbilla Nature Reserve, near Canberra, Australia, where the recordings were made in 1987 by now-retired ornithologist Peter J. Fullagar, who was formerly at the division of ecosystem sciences at The Commonwealth Scientific and Industrial Research Organisation.
While some observations of musk ducks mimicking human sounds were documented in Australian bird journals, they never made it to the scientific community that studies vocal learning, ten Cate explained.
The recordings were made during displays to attract a mate that combine sounds and physical movements such as splashing in the water.
In the recordings, Ripper appeared to imitate the sound of a door a few meters from the sink he was kept in for a few weeks after he was born, as well as what sounds like: "You bloody foo."
The last word could be either "fool" or "food," ten Cate said.
"It's in the ear of the beholder so to speak," he said, explaining that it was likely a phrase Ripper heard repeatedly from his caretaker.
In a separate recording made in 2000, a second male duck at Tidbinbilla appears to imitate a Pacific black duck.
Musk ducks live in two separate areas in western and southeastern Australia, according to the study. These birds are rarely bred in captivity due to the fact that mature males are prone to attacking other waterfowl.
The study also details two other instances of captive musk ducks imitating sounds in their environment, but the birds were not recorded, and therefore the observations not independently confirmed.
Wild musk ducks are unlikely to imitate human sounds, ten Cate said.
"If you only recorded these animals in the field you wouldn't realize that they were actually vocal learners and imitating one another, it's just when they are reared under these special conditions," he said.
The study was published in the journal Philosophical Transactions of the Royal Society B: Biological Sciences.