Have you ever noticed that people tend to develop the accent of their hometown, even if it’s completely different to that of their parents? Well, the same phenomenon has just been discovered in bats, even though it was believed to be unique to human language.
A new study, published in PLOS Biology, found that bats develop the “accent” of their colony, even if it differs from that of their mother, who is their sole care provider.
The researchers separated 14 pregnant Egyptian fruit bats (Rousettus aegyptiacus) into three different artificial colonies. Then, after their pups had been born, the team played recordings of vocalizations from bat colonies to them. Each group heard a different recording with a different accent for a year – one was natural, while the other two were manipulated to contain more high-pitch calls or more low-pitch calls.
The baby bats could still hear their mother’s accent and communicate with her, but by the age of six months – three months after weaning – they had started using the accents from the recordings 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," explained lead researcher Dr Yossi Yovel from Tel Aviv University in a statement. "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.”
A lot of research has looked into how songbirds acquire vocalizations, and they seem to learn songs from specific tutors. But in the case of bats, their dialect is picked up from hundreds of surrounding individuals.
Dr Yovel explained to National Geographic that this isn’t all that surprising since young bats spend their time in a dark cave under their mother’s wing, exposed to the sounds of vast numbers of communicative bats.
Egyptian fruit bats can live in colonies of up to 50,000 and have at least 1,000 individual vocalizations. These sounds are mainly for telling others to move, as the bats jostle for space in their dimly lit caves.
Now the researchers want to find out whether learning a new dialect affects how bats are accepted by foreign colonies. "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," pondered Dr Yovel.
Better understanding how animals pick up dialects and learn to vocalize could tell us more about the evolution of human language.
"There are many interesting avenues yet to explore," said Dr Yovel.