African penguins modify their calls to sound more similar to their partners and colony mates over time, showing a form of vocal learning known in only a few animals
Some penguins modify their vocal calls to become more similar to their partners and colony over time, an ability that was previously known in only a few species, including humans.
Luigi Baciadonna at the University of Turin, Italy, and his colleagues recorded African penguins (Spheniscus demersus) from three different colonies over three years, and also observed the behavioural patterns of one of the colonies to see which penguins were partners or friendly.
They then analysed specific vocal calls, which the penguins make when they are isolated or trying to keep track of their friends. They compared four distinct audio signatures that represent features such as the frequency and amplitude of the calls. The signatures became more similar over time for penguins that were partners or in the same colony, and for penguins that heard more of each other’s calls.
This adaptation could make it easier for penguins to find their partners and friends in a colony. “Imagine that you are in a pub, you are with your friends and the noise of your environment is really super noisy,” says Baciadonna. “What you do is try to start to talk in a certain way so that your communication is more effective.”
The ability to modify calls in response to the environment, known as vocal accommodation, is a key part of vocal learning, a more complex set of skills such as producing new sounds through learning or imitation. Identifying which species display vocal accommodation could provide clues for how vocal learning evolved.
Baciadonna and his team also propose that this accommodation could help with group cohesion and social bonds between individual penguins.
“This result is very interesting, because you find these middle pieces to the puzzle of how vocal learning could be evolved and which selection pressures could be involved,” says Sara Torres Ortiz at the Max Planck Institute for Ornithology in Munich, Germany.
The distance of penguins from humans on the evolutionary tree suggests that vocal accommodation could be common to many species, but a lot more data needs to be gathered first. “There could be a huge variety of different species that are able to modify their vocalisations slightly and have this ability of vocal accommodation, but we don’t know that yet,” says Ortiz.
Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2022.0626
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