New research from the University of Oxford has provided groundbreaking insights into the evolution of bird songs, emphasizing the crucial role that population dynamics play in shaping the diversity and transformation of these songs. Published in the journal Current Biology, this study presents a detailed analysis based on more than 100,000 bird songs and reveals how the movement, turnover, and age distribution of birds within a population contribute to the constant flux of song cultures in wild bird communities.
The study, which spanned three years, focused on the great tit (Parus major), a species of bird that has been intensively studied for over 77 years through the Wytham Great Tit study. Over this period, researchers collected over 20,000 hours of sound recordings from wild populations of great tits in Oxfordshire, UK. The long-term nature of this study, paired with its innovative methods, has provided an unprecedented opportunity to investigate the intricate relationship between bird population dynamics and the evolution of bird songs.
The primary goal of the researchers was to explore how factors such as bird movements, the age structure of the population, and the turnover of individuals influence the diversity of songs, how songs evolve over time, and what determines which songs become popular or fade from the local culture. The research sheds light on how songs are passed down through generations and how they might change based on a variety of factors, including the mixing of age groups within a neighborhood, immigration from other areas, and individual movements.
To track song variation and its evolution across individual birds, the researchers employed a cutting-edge approach by training an artificial intelligence (AI) model to recognize birds based on their songs alone. This method allowed the team to measure differences between individual birds’ songs with precision, tracking changes in song repertoires as individuals came and went within the population. By using this AI-driven model, the researchers were able to uncover patterns and insights into how songs change and diversify over time within the group.
The findings revealed several key insights into how population dynamics shape song evolution in wild birds. One of the most striking observations was that birds of similar age tend to have more similar song repertoires. In mixed-age neighborhoods, however, the researchers found higher cultural diversity in terms of the songs present. This suggests that when birds of different age groups live in close proximity, a greater variety of songs is maintained within the population.
Furthermore, the turnover of songs within a neighborhood is largely driven by the movement of birds—when individual birds leave or die, many of the songs they know disappear with them. Conversely, younger birds who replace them often bring with them a greater enthusiasm for adopting new song types, thus accelerating the pace of song change in the population. This dynamic creates a cycle where older birds act as cultural repositories, continuing to sing older song types that are gradually fading from the population, while younger birds contribute to the introduction of new songs and help maintain cultural diversity.
Interestingly, age was found to serve as somewhat of a brake on the speed of song change. Older birds tend to sing songs that are becoming less common, which helps preserve certain traditional song types within the population. This role is akin to how older generations in human societies often preserve cultural traditions and knowledge that may otherwise be lost to younger generations, akin to grandparents recalling songs or stories that are unfamiliar to today’s youth.
However, the study also showed that age is not the only factor influencing the pace of song evolution. Increased local dispersal—where birds move more frequently within a larger area—or the arrival of immigrant birds from other populations can have a significant effect on song change. When these birds mix more often, they tend to adopt the most common songs, which in turn slows the rate of song evolution. This dynamic mirrors how increased social mobility in human societies can lead to the adoption of more widely spoken languages or dialects, reducing the diversity of languages spoken in any given community.
An additional key finding from the study was the role of ‘homegrown’ songs. In areas where birds stay close to their birthplace, there is a tendency to maintain more unique and diverse song cultures. This is similar to how isolated human communities often develop their own dialects or distinct musical traditions over time. These “homegrown” songs are unique to specific local populations, and they help preserve song diversity within these isolated groups.
The research also highlighted the effect of immigrant birds on local song cultures. While immigrant birds tend to adopt the songs of the area they have moved into, they also enrich the song diversity of that area by learning more songs overall. This process helps keep the local song culture dynamic and diverse, as immigrant birds introduce new elements into the local repertoire while maintaining traditional local tunes.
Lead researcher Dr. Nilo Merino Recalde, from the Department of Biology at the University of Oxford, commented on the significance of the findings: “Just as human communities develop distinct dialects and musical traditions, some birds also have local song cultures that evolve over time. 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.” Dr. Recalde further emphasized that this research not only provides valuable insights into bird behavior but also offers a new perspective on how demographic changes in animal populations might shape cultural evolution.
This study is the first extensive test of the role of demography—specifically, individual movement and survival—in driving cultural diversity and evolution within a wild animal population. The researchers used individual-level data and an extensive dataset of song variation to explore how these demographic factors influence cultural change. This approach is not only groundbreaking for understanding bird song evolution but also sets a precedent for future studies in other animal species, as researchers seek to understand how demographic processes impact the development of cultural traits across the animal kingdom.
The complete dataset from this study has been made publicly available, offering an invaluable resource for other researchers to explore the intricacies of bird song variation and cultural evolution. This open access to data helps ensure that the findings will continue to contribute to the broader scientific understanding of animal behavior and cultural transmission.
Professor Ben Sheldon, also from the University of Oxford’s Department of Biology and a leader of the long-term bird study in Wytham Woods, expressed his excitement about the findings: “Our work here shows, once again, that tracking individuals over their lives allows us to understand so much of the way that different processes interact in natural populations. 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.”
This research not only enriches our understanding of how bird songs evolve but also sheds light on broader questions related to cultural transmission and evolution in the animal kingdom. The implications of these findings are far-reaching, offering valuable insights into the role of demographic processes in shaping the cultural diversity of species, and how these insights can be applied to conservation efforts. Understanding how cultural traits evolve and change over time could inform strategies to protect biodiversity and preserve the unique cultural identities of animal populations. The continued study of bird songs and other cultural behaviors in animals promises to provide even more profound insights into the forces that drive cultural evolution across species.
More information: The demographic drivers of cultural evolution in bird song, Current Biology (2025). DOI: 10.1016/j.cub.2025.02.016. www.cell.com/current-biology/f … 0960-9822(25)00150-2