Some birds sing the same song for a million years.
Listening to family members and neighbors may help many songbirds learn new songs. In order to reproduce the sounds they hear, they write songs that are somewhat different from one another from year to year.
An investigation of the songs of East African sunbirds has shown that the sounds have stayed almost constant for more than 500,000 years. The songs of these creatures may even have remained almost unchanged for as long as 1 million years, making them sound almost identical to distant cousins.
The eastern double-collared sunbird (Cinnyris mediocris) was the subject of the scientists’ investigation. This species lives in the highlands of the Eastern Afromontane, which constitute a biodiversity hotspot in East Africa.
Sunbirds are brilliantly colored birds that primarily subsist on nectar for their food source.
These birds are characterized by intricate territorial songs that are distinct from those of other species.
The research was carried out by biologists from the University of California, Berkeley, and Missouri State University in Springfield.
In particular, we were interested in speciation (how new species emerge) and how features differ across populations throughout the speciation process. According to the first author, Jay McEntee, an associate professor of biology at Missouri State University, “isolating oneself is regarded to be key in this process in birds.”
In the end, the sky island forests of Eastern Africa prove to be an excellent location for studying communities that are geographically separated from one another.
Known as “sky island sunbirds,” these sunbird species dwell separate from other birds on the peaks of high mountains in forests known as sky islands, where they are protected from the rest of the world.
Rauri Bowie, a professor of integrative biology at the University of California, Berkeley, conducted his Ph.D. thesis on these birds, demonstrating that what was previously thought to be two species of eastern double-collared sunbirds that were found on mountaintops throughout East Africa was actually five or possibly six species.
While they seemed to be genetically identical, they were not, leading Bowie to question whether their songs had stayed intact, just as their feathers did.
It was with Bowie’s help that they discovered the answer, traveling to virtually all of the sky islands in East Africa and recording a total of 356 songs from 123 distinct birds belonging to six lineages of eastern double-collared sunbirds.
“It was a wonderful pleasure to do this study.” – While flying to and from these many sky islands, we met a lot of amazing folks. There were instances when we went to make sound recordings of populations and the birds sounded nothing like what we had anticipated they would sound like, or they were clearly different from what we had expected in some specific regard,” McIntee adds.
The researchers said that in other cases, particularly where Rauri’s research had shown a significant genetic variation within a given population, they anticipated to discover birds that sung differently from their closest relatives, but they never did. At times, this was a bit disheartening; nevertheless, since it was so unexpected, it turned out to be a really engaging aspect of the tale.”
These researchers’ results were reported in the Proceedings of the Royal Society B: Biological Sciences publication.
Understanding the Reasons for Change in the World
A bird’s song is often learned by its parents and other birds in their immediate vicinity. Nevertheless, this learning process is prone to mistakes and changes with time.
It has been shown that many song-learning birds create their songs depending on what they hear from other birds of their own species. Individuals’ songs, on the other hand, are not exact replicas of other birds’ songs that they’ve heard.
According to McIntee, birds “blend components of other songs they’ve heard and add variety in a way that is similar to improvisation.”
Similarly to how languages change via these methods, bird song may evolve through similar processes as well. ” It has been predicted that these types of changes accumulate in isolated groups over time, and that this would result in divergence in measures we can make, such as song length or pitch.”
There is no definitive explanation for why the East African sunbirds’ songs have not developed through time.
In particular, one thing that’s particularly remarkable about the sky islands where these sunbirds reside is that they seem to have a high degree of environmental stability through time,” the researcher said.
The temperature on these sky islands seems to have been rather steady in comparison to other areas, and there is evidence that forest has consistently covered them through global climatic fluctuations that have produced profound changes in biological groups in other parts of the planet. According to McIntee, “we believe this is a critical aspect.”
It has been discovered that a number of species that reside throughout sky islands in East Africa, despite having spent long periods alone, have altered little in terms of other features (such as plumage and morphology).
According to the scientist, understanding why things change—and why they don’t—is critical for science.
When it comes to evolution, McIntee adds, “we spend a lot of effort trying to figure out why things change.”
In my opinion, the fact that we have discovered this kind of consistency in learned traits, of all things, over time really underscores this point.” “It is not a novel point to make that we need to spend time thinking about what constrains change as well, but I think that the fact that we have found this kind of consistency in learned traits, of all things, really underscores this point.
Some birds sing the same song for a million years.
Maybe a million years ago, the “sky island” highlands of East Africa were home to a soundscape that sounded quite similar to the one that we hear now. The reason for this is because a group of small, brightly colored birds has been singing the same same songs for more than 500,000 years — and maybe for as long as 1 million years, according to a recent research — and they are still repeating them.
Colorful, small nectar-feeding birds belonging to the Nectariniidae family, sunbirds are found across Africa and Asia. They are similar in appearance to hummingbirds and feed on nectar.
According to senior author Rauri Bowie, who is a professor of integrative biology at the University of California, Berkeley, as well as a curator at the school’s Museum of Vertebrate Zoology, these are the “small diamonds that arise before you.”
In East Africa, from Mozambique to Kenya, the eastern double-collared sunbird (Cinnyris mediocris), sometimes known as the “sky island sunbird,” may be found on the peaks of steep mountains, where it can be found at the tops of towering mountains.
For tens of thousands to a million years, these towering summits have kept distinct populations, or lineages, of this species apart from one another. The sky island sunbirds are almost indistinguishable from one another, despite the fact that they do not interact at all.
Whether the songs of the birds had not altered over time, Bowie and his crew questioned if the songs of the birds had as well. 123 unique birds from six distinct sunbird lineages were recorded singing their songs on 15 different sky islands in East Africa between 2007 and 2011.
This information was used to answer the issue. In order to determine how the sunbirds’ songs evolved, they created a statistical approach.
According to the results of the study, some of these secluded communities are still singing the same tunes.
According to this, these songs have not changed much during the thousands of years that these lineages have been separated. According to the statement, the researchers also discovered, after analyzing genetic differences among the populations, that the two populations of a species that had been separated for the longest period of time had nearly identical songs, whereas two other populations that had been separated for a shorter period of time had songs that were very different from each other.
Biologists normally anticipate bird songs to vary and alter over time in diverse populations, so the team’s results were a little surprise. Observations of birds in the Northern Hemisphere, where climatic circumstances have altered several times over tens of thousands of years, led to the hypothesis that bird songs quickly develop, according to Bowie.
In order to better adapt to various conditions, such as the existence or absence of glaciers in the Northern Hemisphere, it is believed that birds in this region have developed new colors, songs, and behavior.
Nonetheless, since the highlands of East Africa have witnessed relatively little geological change through time, it is unlikely that the sunbirds had any incentive to acquire distinct plumage or songs.
After doing their research, the researchers came to the conclusion that birds, and their songs, may remain unchanging for millions of years until environmental disturbances lead them to develop swiftly or in pulses, as shown by the study’s conclusions.
When individuals are isolated for a long period of time, their dialects often shift; after a while, you can determine where someone is from based on their accent. In the same manner, songs have been interpreted,” Bowie said.
Our research suggests that this isn’t always the case for birds, as our publication demonstrates. There may be protracted periods of stagnation even in characteristics that should be very labile, such as singing or plumage.”
In order to determine why certain birds develop fresh songs while others do not, the scientists are now doing more study in East Africa to this end.