You wouldn't miss one of Australia's musk ducks if you saw it. The name comes from the musky smell the ducks waft around during the breeding season, and the males have a large, black lobe below their bill.

But if the musk duck you're hanging out with is called Ripper, the other dead giveaway is… swearing. With human words. For animal researchers this is an exciting find, and new research has looked into how a few of these particular species of duck ended up with that trait.

"Acquiring vocalizations by learning them from other individuals is only known from a limited number of animal groups," ethologists Carel ten Cate (Leiden University) and Peter Fullagar write in their new paper.

"Here, we provide evidence for vocal learning in a member of a basal clade of the avian phylogeny: the Australian musk duck (Biziura lobata)."

One duck – Ripper – was hand reared at the Tidbinbilla Nature Reserve South West of Australia's capital Canberra back in the 80s, and he learnt how to remarkably imitate the sound of a slamming door (you can hear it below) as well as a phrase that sounds a lot like 'you bloody fool'.

How Ripper ended up learning this particularly Australian phrase is unknown to the researchers, although they believe it was likely something his caretaker would say, and the bird learnt to repeat it.

"Ripper was raised from a fresh egg sourced from East Gippsland, Victoria, Australia in September 1983 and was the only musk duck present at the time of rearing," the researchers write in their paper.

"Unfortunately, all documents from Tidbinbilla were lost in the wildfire that swept through the reserve in January 2003 making it difficult to establish all the exact details."

Fifteen years later, a second duck – also male – also lived at Tidbinbilla, but was reared by a female in captivity, rather than a human caretaker. He was recorded in June 2000 sounding like a completely different duck – a Pacific black duck (Anas superciliosa). Sadly, much of the information about this duck was also lost in the same fire.

However, we do know that both of the ducks would use these imitation noises during their mating displays. (Can you imagine the mix of noise and musk smell?)

These fascinating events happened quite a while ago, but the researchers have now submitted this case as part of a special issue of the journal Philosophical Transactions of the Royal Society of London B focusing on 'vocal learning in animals and humans'.

"These sounds have been described before, but were never analyzed in any detail and went so far unnoticed by researchers of vocal learning," the researchers write.

"Together with earlier observations of vocal differences between populations and deviant vocalizations in captive-reared individuals, these observations demonstrate the presence of advanced vocal learning at a level comparable to that of songbirds and parrots."

The pair of ethologists also notes a number of other unrecorded male musk ducks in the UK which have mimicked human coughing, a snorting pony, and the squeak of a turnstile.

The reason the researchers are interested now is because very few animals can imitate vocal noises like these musk ducks could. Musk ducks are the only living member of their genus, and are very distantly related to other birds that can mimic noises such as song birds and parrots.

So, why can the musk duck mimic? Interestingly, the part of the brain associated with vocal learning in songbirds and parrots, the telencephalon, is also relatively larger in waterfowl than in other groups of birds.

While not entirely sure, the researchers do suspect the musk duck evolved its mimicking ability separately to other mimicking species because these birds are near the trunk of the bird evolutionary tree – meaning if it evolved once very early on within them, the ability must then have been lost many times since. So, it would make more sense that it evolved separately a few times instead.

"Vocal learning in the musk duck would represent a case of independent evolution, raising many questions ranging from the neural and behavioral mechanisms involved to the evolutionary and adaptive background of vocal learning in this species," the researchers write.

"Therefore, the reported imitations call for a more extensive documentation and analysis."

There's plenty more research to be done yet. As the researchers explain, we don't even know which living species are closest to the musk duck, although we do know that no other duck or fowl has shown such ability.

Until we find out more about this amazing species, in the words of Ripper the duck – we're bloody fools.

The research has been published in Philosophical Transactions of the Royal Society of London B (link not yet live at time of publishing).