Over the past 50 years since monk parakeets (Myiopsitta monachus) first arrived in Europe from South America, the invasive species has spread throughout the continent and developed distinct dialects that vary between countries and even cities, according to a team of researchers from the Max Planck Institutes of Animal Behavior in Konstanz and Human Evolution in Leipzig, Germany.
Through a novel analytical method, the scientists compared the calls of monk parakeets in eight cities across four European nations and discovered that the parrots “sound” different in each location. Just like humans, monk parakeets living in Europe have unique ways of communicating depending on where they reside, explains lead author Stephen Tyndel, a PhD student at the Max Planck Institute of Animal Behavior.
Europe is home to no native parrot species. However, several species including monk parakeets have established feral populations after escaping or being released from the pet trade. Originally from South America, monk parakeets now thrive in large numbers across parts of Europe.
As with all parrots, monk parakeets have an exceptionally flexible vocal repertoire and can imitate and learn new sounds throughout their lifetime. As this invasive species has only recently spread across the continent, Tyndel says the monk parakeets provide the perfect test subject to study how complex communication evolves in a non-human species.
To determine if monk parakeets developed dialects – meaning calls that differ based on the birds’ location – the researchers recorded parakeets in eight cities spanning Spain, Belgium, Italy, and Greece. A novel statistical method allowed them to check if the parrots’ calls were different between cities and even between parks within the same city. We wanted to understand not just if there are distinct dialects, but at what geographic scale they occur, says Tyndel.
They discovered the parrots had distinct dialects in each city. For example, the monk parakeets in Brussels had contact calls notably different from other locations, says co-lead author Simeon Smeele, a scientist affiliated with both the Max Planck Institute of Animal Behavior and the Max Planck Institute of Human Evolution. In most cases, dialects varied in the frequency modulation structure within each call, which is very difficult for humans to perceive, adds Smeele.
However, when scientists looked for dialects within parks of each city, they found no differences. The parrots did not have unique calls from one park to another. Taken together, this suggests the parrot dialects diverged early when the birds invaded European cities but have not changed significantly since, says Tyndel.
The results were surprising, says Tyndel. This implies dialects arose through a passive process – birds copying others and small errors accumulating to gradually differentiate cities – or differences existed initially and have remained over time.
But the team has not ruled out active processes also forming dialects, which could aid social communication such as recognizing flockmates. Within parks, monk parakeets nest in tightly packed colonies. Researchers believe vocal differences like local vernacular may exist in these smaller social units.
We think dialects could be used to communicate who belongs to which nest group, as a kind of passphrase, says Smeele. Future work will aim to understand how individuals learn from each other and whether smaller park groups exhibit dialects.
This will further our understanding of parrot communication, says Tyndel, and provide insights into how complex communication is linked to the complex social lives of both humans and animals.
Sources
Max Planck Institute of Animal Behavior | Simeon Q Smeele, Stephen A Tyndel, Lucy M Aplin, Mary Brooke McElreath, Multilevel Bayesian analysis of monk parakeet contact calls shows dialects between European cities, Behavioral Ecology, 2023;, arad093, doi.org/10.1093/beheco/arad093
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