These sunbirds keep singin' their song
Sky-island populations of East African double-collared sunbirds have been isolated from one another for hundreds of thousands if not a million years, but still look very similar. While almost indistinguishable in plumage, however, some of these bird lineages have altered their songs a lot while others have not — their songs differ little from the songs of related populations they’ve not encountered for millennia.
A new study by biologists from the University of California, Berkeley, and Missouri State University in Springfield, however, documents songs in East African sunbirds that have remained nearly unchanged for more than 500,000 years, and perhaps for as long as 1 million years, making the songs nearly indistinguishable from those of relatives from which they’ve long been separated.
The amazingly static nature of their songs may be due to a lack of change in these birds’ environments, which are stable mountain forests — so-called sky islands — isolated from other sky island populations of the same or similar species for tens of thousands to millions of years. The coloration of the birds’ feathers has changed little, as well, making their plumage nearly indistinguishable from each other, even though some are separate, but closely related, species.
“If you isolate humans, their dialects quite often change; you can tell after a while where somebody comes from. And song has been interpreted in that same way,” said senior author Rauri Bowie, UC Berkeley professor of integrative biology and a curator in the campus’s Museum of Vertebrate Zoology. “What our paper shows is that it’s not necessarily the case for birds. Even in traits that should be very labile, such as song or plumage, you can have long periods of stasis.” CONT'D...
For full story, visit: https://news.berkeley.edu/2022/01/12/...
Video by Roxanne Makasdjian and Alan Toth
Audio courtesy Jay McEntee
Sunbird video clip, 00-:22, courtesy Oliver Fowler
Thanks to Macaulay Library, Cornell University
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