Tag Archives: vocalization

This Australian duck says ‘You bloody fool’ and can imitate other sounds — and scientists couldn’t be more fascinated

Musk duck. Credit: Wikimedia Commons.

When biologist Carel ten Cate heard rumors of a talking duck in Australia, he brushed it off like a comical anecdote, like any sane human being. But his curiosity got the better of him, so he tracked down a well-respected Australian scientist who first noticed this phenomenon more than three decades ago. After listening to verified footage showing an adult musk duck vocalizing the sounds of a door slamming or squeaking, a pony snorting, a man coughing, and even the all too familiar slur “You bloody fool!”, the Dutch biologist was simply stunned. Listen for yourself

Carel ten Cate’s encounter with this articulate duck led him down a rabbit hole in which he found more evidence that musk ducks (Biziura lobata) can mimic sounds from nature, as well as those made by humans.

This extraordinary ability, which was documented in the Philosophical Transactions of the Royal Society of London B, officially allows the musk duck to join an exclusive club of animals that are capable of acquiring vocalization through learning, which includes parrots, hummingbirds, and some songbirds, as well as some whales, seals, dolphins, and bats on the mammalian front.

“These sounds have been described before, but were never analysed in any detail and went so far unnoticed by researchers of vocal learning,” said ten Cate, who is a professor of animal behavior at the Leiden University, wrote in his study. His co-author is Australian scientist Peter J. Fullager, who first documented a musk duck imitating sounds over 30 years ago.

Nearly all mammals produce some vocal sounds, from dogs barking and howling to cattle lowing and mooing. Humans are very different in that they can string together sounds that have particular meanings, which we call words, allowing us to communicate with one another through language. But at the same time, while most mammals are born with innate vocalization abilities, humans are not.

We all need to learn how to speak and the brain processes that support this type of learning are still poorly understood. This is why studies such as this that probe acquired vocalization in other species are important for unraveling these processes.

Vocal learning refers to imitating sounds or producing completely new vocalizations, depending on the species involved. Central to this ability seems to be auditory feedback during development.

“Most species have a more innate ability to learn how to make sounds. But a few rare animals, including a handful of mammals and, of course, human beings, are vocal learners. They need auditory feedback to learn how to make the right sounds if they want to communicate,” said Michael Yartsev, assistant professor of bioengineering at the University of California, Berkeley, in a 2020 interview with the Dana Foundation.

Yartsev’s earlier studies with Egyptian fruit bats showed that individuals that have been isolated or exposed to unique acoustic environments right after they were born had different vocalizations than groups of bats that were raised normally.

“This suggests that their vocalizations have some plasticity. Our own work has shown that, even in adults, if you expose the bats to sound perturbation, they have the capacity to modify or adapt their vocalizations in a stable manner over prolonged periods of time. So, there are good indications that there is some form of plasticity there that we can investigate,” Yartsev said.

The musk ducks seem to be this way too. Besides the musk duck that imitated his former caretaker’s insults, ten Cate identified another musk duck that was raised alongside Pacific black ducks (Anas superciliosa), and consequently quacked like them. Both ducks were raised in captivity since they were hatchlings. Wild musk ducks sound very different and they do not care to acquire new sounds in their vocal repertoire, which also explains why their vocalization acquisition abilities have been overlooked until now — they apparently make for horrible pets.

Furthermore, not all captive musk ducks seem to imitate non-native sounds. Captive female musk ducks don’t perform vocal displays, and the imitations performed by the males were part of their advertising displays to potential mates.

“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. We discuss the rearing conditions that may have given rise to the imitations and suggest that the structure of the duck vocalizations indicates a quite sophisticated and flexible control over the vocal production mechanism,” the scientists wrote in their new study.

Ducks split off from the evolutionary family tree sooner than other birds, such as parrots and songbirds. What’s more, duck brains differ quite a lot structure-wise than their avian relatives. Therefore, the “observations support the hypothesis that vocal learning in birds evolved in several groups independently rather than evolving once with several losses,” the researchers concluded. 

This article was originally published in September, 2021.

Fruit bats.

Young bats learn different dialects from their nest mates

When traveling in a foreign country, it helps to learn a couple of basic words and phrases. Things like ‘I’m lost, can you help me?’ or ‘I need to see a doctor’ could prove highly useful and might even save your life. Bats seem to think so too. According to a recent study, young wild fruit bats learn to respond to the calls of different group sounds they are immersed in, even if this “dialect” isn’t the same as their own. Most often, this is a response to a “move out of my way” signal, which can be important to utter in a crowded cave environment packed with thousands of winged mammals.

Fruit bats.

Credit: Pixabay.

The team of researchers at Tel Aviv University raised 14 bat pups with their mothers in three different chambers, with each mum giving birth and raising her young in one of the colonies. In these lab colonies, researchers played three specific subsets of natural bat vocalizations from loudspeakers. The sounds mimicked real cave roosts comprised of 300 bats and were played in different ranges of pitch.

The young bats were also, of course, exposed to their mothers’ normal ‘dialect’ which they used to communicate among themselves. At the same time, each group developed the ability to react to a dialect that resembled the cave roost they were exposed to.

“The difference between the vocalizations of the mother bat and those of the colony are akin to a London accent and, say, a Scottish accent,” Dr. Yossi Yovel of Tel Aviv University explains. “The pups heard their mothers’ ‘London’ dialect, but also heard the ‘Scottish’ dialect mimicked by many dozens of ‘Scottish’ bats. The pups eventually adopted a dialect that was more similar to the local ‘Scottish’ dialect than to the ‘London’ accent of their mothers.”

Human babies and toddlers have a fantastic ability to pick up new languages, soaking patterns and utterances like a sponge. Scientists call this ability ‘vocal learning’ and until recently it was thought to be exclusively the domain of humans and some songbirds. Other animals have been shown to use a form of vocal learning, but these were instances where the animals would mimic human sounds. The young fruit bats, on the other hand, seem capable of vocal learning among their own species, as reported in the journal PLOS Biology. 

“The ability to learn vocalizations from others is extremely important for speech acquisition in humans, but it’s believed to be rare among animals,” Dr. Yovel says. “Researchers have believed that this is what makes human language unique.”

Studies on songbirds suggest that they can learn to sing from one parent. The new study, however, shows that bats tuned in and learn from an entire colony comprised of hundreds of bats. This finding is striking because it finally moves science away from the songbird-model. It also poses important evolutionary questions like whether or not vocal learning appeared independently in humans or whether it’s actually a far more primitive behavior shared among the mammalian group.

“Will they adopt the local dialect or will they be rejected by the group? Or maybe the local colony will change its dialect to adopt that of our bats,” Dr. Yovel says. “There are many interesting avenues yet to explore.”

It’s not the first time bats have surprised researchers with their complex communication. Earlier this year, the same team found that bats discuss and even argue with each other.