Which songs birds sing can – as with human music – be influenced by age, social interactions and migration, researchers have found.
Not all birds learn songs, but among those that do, individuals, neighbourhoods and populations can produce different collections of tunes, akin to different music albums.
Now researchers have found that changes in the makeup of a group of birds can influence factors including which songs they learn, how similar those songs are to each other and how quickly songs are replaced.
Dr Nilo Merino Recalde, the first author of the study, from the University of Oxford, said: “This is very interesting, I think, partly because it shows that there are all these kind of common elements at play when it comes to shaping learned traits, [similar to] what happens with human languages and human music.”
But he said the parallels had their limits. “The function and the role of human music and language is very, very different to the function of birdsong,” he said. “Birdsong is used to repel rivals, to protect territories, to entice mates, this kind of thing. And that also shapes songs.”
Writing in the journal Current Biology, Recalde and colleagues describe how they used physical tracking as well as artificial intelligence to match recorded songs to individual male great tits living in Wytham Woods in Oxford. In total, the study encompassed 20,000 hours of sound recordings and more than 100,000 songs, captured over three years.
The researchers used their AI models to analyse the repertoires of individual birds, those within neighbourhoods and across the entire population to explore how similar the various songs were. As a result, the team were able to unpick how population turnover, immigration and age structure influenced the songs.
The team found that within a neighbourhood of great tits, birds of a similar age tended to sing a similar selection of songs.
Birds of a more advanced age tended to belt out older songs that were less common among the population as a whole – similar to how older people might hum more traditional tunes.
Recalde said this was because great tits learn their songs in the first year of life. As a result, neighbourhoods with a greater mix of ages showed a greater diversity of songs.
Movement also mattered. The team found new arrivals to a neighbourhood adopted local songs rather than introducing new ones – something Recalde said was down to dispersals typically happening when the birds were very young and hence still learning songs.
But he added: “In the process, something interesting happens which we don’t fully understand, which is that they seem to end up with a slightly larger repertoire.”
The researchers said neighbourhoods where birds tended to stay put had more unique “homegrown” tunes, possibly because they were less influenced by the songs sung elsewhere. By contrast, Recalde noted, greater movement meant repertoires became more similar because birds were more likely to sing “popular” tunes common throughout the population.
Recalde said that as well as shedding light on how culture changed among the birds, the research raised new possibilities for conservation.“[It] might let you say something about populations and their status and their structure and how well they’re doing based on the songs themselves, without having to catch the birds,” he said.
