The changing chorus: Study shows how movements and memories influence birdsong evolution - University of Oxford

New research from the University of Oxford has provided fresh insights into how bird songs evolve over time, revealing a significant role for population dynamics in shaping song diversity and change. The findings – based on an analysis of over 100,000 bird songs – have been published today in the journal Current Biology.

The researchers spent three years collecting over twenty thousand hours of sound recordings from a wild population of great tits (Parus major) in Oxfordshire, which has been studied for the past 77 years as part of the Wytham Great Tit study. Their aim was to investigate how the movement, age, and turnover of birds within a population influences the diversity and evolution of their songs – including which songs become locally popular, which fade away, and how varied their song repertoires become.

To achieve this, they used a new approach involving training an AI model to recognise individual birds based on their songs alone and measure song differences between individuals. This method allowed them to track variations in song repertoires across the population and uncover patterns in song evolution.

The results showed that birds of similar age tend to have more similar repertoires, with mixed-age neighbourhoods having higher cultural diversity. Furthermore, the pace of song turnover within neighbourhoods is driven by individuals coming and going; when birds leave or die, many song types disappear with them and the young birds that replace them can speed up the adoption of new song types.

At the same time age serves as a brake on change, as older birds continue to sing song types that are becoming less frequent in the population. 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.