Sky Island Sunbirds Have Been Singing the Same Song For Up to A Million Years Despite Ecological Changes

Bird song was previously thought to change when passed down to the next generation by mimicry because it is susceptible to distortion. MailOnline reported that researchers from the University of California, Berkeley recently found that sky island sunbirds who lived in isolated forests in East African mountains have been singing the same song for up to a million years.

The team noted that despite changes in the birds' habitats, they are still singing very similar songs rather than changing tunes slowly over time. They said that it appears East African sunbirds undergo long periods of stasis punctuation through the rapid pulse of change.

(Photo : Unsplash/ Musiime Muramura)
The Red-chested sunbird (Cinnyris erythrocercus)

East African Sunbirds Keep Singing Their Song

According to Live Science, researchers have sought to answer whether bird songs have remained unchanged throughout eons. They visited 15 different sky islands in East Africa between 2007 and 2011 and recorded songs from 123 birds from six different lineages. After which, they developed a statistical method that can analyze the evolution of the songs of sunbirds.

They found that some of the isolated sunbirds are stuck on a retweet, singing the same songs that have not evolved much in the thousands or even a million years of the separation of lineages.

More so, they found through genetic analyses that sunbird populations differ in terms of genetics in which two populations who have been separated the longest have identical songs. On the other hand, those separated for a shorter time had very different songs.

 Biologists said that the findings were surprising because bird songs are expected to evolve and change over time, especially in different bird populations. They explained that the rapid evolution of bird songs is due to the changes in their environment throughout time. For instance, a study on birds in the Northern Hemisphere revealed that those birds did not only change their colors, but their songs also adapted to their environment, whether in the presence or absence of glaciers.

But this was not the case on sunbirds living in the mountains of East Africa, a place that has seen very few ecological changes that could explain why sunbirds have not evolved much in terms of their plumage or songs. Researchers said in a video that sunbirds in the area and their songs could stay unchanged for another million years if there are no environmental shifts that could trigger an evolution.

Study senior author Rauri Bowie, a professor in integrative biology at the University of California, Berkeley, said that isolating human populations will make it easier to identify who comes from where because of their dialects. Now, scientists said that they are continuing to study East Africa sunbirds to know why some of them evolve newer songs while some do not.

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Importance of Bird Song

Bird songs are important for a variety of reasons depending on the season. But according to The Spruce, the most common importance of bird songs are for marking their territory, courtship, mating, and general communication.

The article explains that loud, complex songs signal other birds to stay away from an already inhabited territory. Birds can judge their chances of success by interpreting the complexity and strength of the songs.

Birds use songs in their courtship rituals to attract a mate. Male birds let nearby females know that he is strong and able to defend themselves and the nest for a higher chance of raising healthy chicks. This also advertises that they are no longer available to other single birds.

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