A great tit. (iStock)
They sound beautiful, herald the start of spring, and even have the power to reduce stress and boost mental health.
Now it turns out that some birdsongs also contain a hidden world of shared language, with varying local accents and dialects that change depending on the age of the bird and its peers — not unlike human songs.
“Just as human communities develop distinct dialects and musical traditions, some birds also have local song cultures that evolve over time,” said Nilo Merino Recalde of the University of Oxford’s biology department, who led the new research published Friday in the journal Current Biology. “Our study shows exactly how population dynamics — the comings and goings of individual birds — affect this cultural learning process, influencing both song diversity and the pace of change.”
The variations in birdsongs aren’t just beautiful, the scientists add — they also have critical implications for conservation efforts in the future.
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The study is based on analysis of over 100,000 bird songs from at least 242 birds recorded in 2020, 2021 and 2022 in Wytham Woods in Britain’s Oxfordshire — a sprawling 1,000-acre wood where ecological and environmental research is carried out. For the last 77 years it has been the site of the Wytham Great Tit Study showing how two species of tit — the great tit and blue tit — have changed over time. Great tits, also known as Parus major, are common across Europe and related to chickadees found across the United States, according to the Cornell Bird Lab.
While some birds learn songs from their fathers and others learn continuously from neighbors, great tits are believed to do most of their learning in the first 10-11 months of life, researchers said, leading to a “final crystallised song repertoire that remains relatively stable afterward.”
Great tits are famous for an “iconic, high-pitched and squeaky ‘see-saw-see-saw’ song” according to Britain’s Natural History Museum, which has also been described as like a bicycle pump being used or written as a “teacher, teacher” sound. Females recognize their male counterparts based on these songs.
Merino Recalde said he was inspired by his love of birds and interest in social learning in animals, which creates an evolving shared culture reminiscent of the way humans learn languages and music. Theoretical work indicates that factors such as population turnover, immigration and age can affect the evolution of these cultural traits — so far, however, empirical evidence on the subject has been limited.
His research team focused on the great tit, a small bird that lives just 1.9 years on average. The team recorded the “dawn chorus” from March to May — coinciding with breeding season — using microphones placed near nesting boxes to gather more than 200,000 hours of the “simple yet highly diverse songs” sung by males. Through a combination of physical capture, microchips and an artificial intelligence model, researchers were able to recognize the songs of individual birds and track how they changed over time, showing each bird had a repertoire ranging from one to more than 10 tunes.
“One of the main findings was that the distance that these birds travel while they are learning the songs, and also the ages of the other birds they interact with … affect how varied their songs become, collectively,” Merino Recalde said.
Results showed that dispersal within the population — referring to how far the birds traveled from where they were born to where they settled down to breed — “homogenises song culture” over time and slows down the pace of change. Immigrant birds also were shown to adopt local songs and learn more songs overall, helping to enrich the “musical scene,” researchers said.
By contrast, “homegrown” songs in areas where birds stay close to their birthplace tend to stay unique, similar to the way in which isolated human communities can develop distinct local dialects over time, the team found.
Age also had a significant impact, with birds of a similar age singing similar tunes, whereas mixed-age neighborhoods had “higher cultural diversity.” This shows that the older birds can act as guardians of culture as they “continue to sing song types that are becoming less frequent in the population,” researchers said. “In this way, older birds can function as ‘cultural repositories’ of older song types that younger birds may not know, just as grandparents might remember songs that today’s teenagers have never heard.”
The discovery adds another dimension to the birdsong heard each spring, said Professor Ben Sheldon of the University of Oxford’s biology department, who leads the long-term study at Wytham Woods. “It’s thrilling to think that we can explain the acoustic landscape we hear in the woods each spring in terms of the result of the cumulative combination of individual movements and survival over many years.”
Merino Recalde said capturing how population changes are reflected in song could provide a future avenue for less invasive research, eliminating the need for capturing and tagging animals, for instance.
He noted that this study only examined one bird population in Britain, and that further research to cover more ground and different species would be beneficial.
Professor Richard Gregory, the head of monitoring conservation science at Britain’s Royal Society for the Protection of Birds (RSPB), who was not involved with the study, praised the “herculean” effort to analyze such a large data sample over a three-year period and said similar research could be used to highlight “critical tipping points” for a population in future.
While the great tit is not endangered, Gregory said the study could help inform plans to reintroduce or relocate certain animals, as such conservation efforts may be “doomed” if they don’t take their cultural traits into account. “This study reminds us that the details of an animal’s life really matter.”
Gregory, who is also an honorary professor of genetics, evolution and environment at University College London, said the study also showed that “methods of wildlife recording and song analysis are developing at break-neck speed,” and AI is going to “revolutionize conservation science” by allowing patterns in nature to be identified more readily.