The magnificent plumage and song of the highland sunbird in East Africa differ little from separate, related species. Researchers conclude that the songs of these birds have not changed for hundreds of thousands of years.
Biologists working with Rauri Bowie from the University of California at Berkeley studied the songs of six different sunbird species of the genus Cinnyris, which live isolated from each other in the tropical mountain regions of East Africa and yet sing and look very similar. Based on the differences in the DNA, the researchers determined how long the species had been separated from each other.
It turned out that deviations in singing did not correlate with this period of time. The songs of some species can hardly be distinguished, even despite very different genomes. From this, the researchers conclude that the songs of these birds have in some cases hardly changed for around 500,000 years, possibly even a million years. They suspect that this was made possible by the almost constant environmental conditions during this period.
Characteristics such as song and plumage do not necessarily change in an isolated bird population, as is known from divergent dialects in humans. Genetic or cultural changes therefore do not appear to be automatic triggers for changes in these characteristics. This is a surprising result since song and plumage are very plastic features. The team now wants to further investigate what factors contribute to birds chirping new songs – and why others stick to the tried and tested ones.