The researchers speculate that female sparrows may be attracted to him.
This is an Inside Science story.
When researchers first noticed white-throated sparrows singing a strange song in the Canadian province of British Columbia, they thought it was a regional dialect. Dialects are common among birds and other singing animals that live in isolated populations.
Then the song began to spread.
“It was very exciting to see this wave across the country,” said Ken Otter, a biologist at the University of Northern British Columbia. “Basically it’s like it’s going viral.”
Traditional white-throated sparrow songs start with three long whistles and end with a series of quick notes in groups of three. Canadian bird watchers compare the beat to “Oh my sweet Canada, Canada, Canada.” With the new song, the birds release the third note of some of the triplet phrases, turning the song into “Oh, my sweet Cana Cana Canada”.
Using recordings from a variety of sources, the researchers saw that the new doublet song spread eastward over the past two decades. By 2019, only birds in the far eastern part of the country were still singing the classic triplet song. The new song spread like a disease; in fact, the researchers used statistical disease tracking techniques to analyze their data. But as a behavioral phenomenon, it resembled human trends and fashions, Otter said. He and his colleagues published their findings July 2 in the journal Current Biology.
How did this happen? The movements of the sparrows offer clues.
Historically, white-throated sparrows were raised east of the Rocky Mountains in Canada and spent winters in the central and eastern United States, but in the mid-20th century, a breeding population appeared west of the Rocky Mountains. in British Columbia. At about the same time, sparrows began to appear in California during the winter.
The researchers initially assumed that birds on both sides of the Rocky Mountains were isolated from each other, with western birds wintering in California and eastern birds wintering in the other parts of the US But genetic testing and Tracking device data revealed that birds from both regions were mixing.
Otter and his colleagues found that some of the birds in British Columbia overwinter in California, while the rest overwinter in Texas and Oklahoma, part of the historic winter range for birds that are also used by Canadian prairie sparrows. . White-throated sparrows sing during the winter, so birds on both sides of the Rocky Mountains would have a chance to learn from each other.
Otter and his colleagues aren’t sure why the doublet song became so popular, but they speculate that female sparrows may be drawn to the novelty. In fact, a third song variant that adjusts the middle note volume has recently appeared in the West, and it appears to be spreading even faster than the doublet song.
Citizen science projects such as eBird and Xeno-singing make it possible to study such phenomena more effectively than ever.
“Suddenly, there are people across North America carrying songs,” said Otter. “There is no way we can see this type of spread if we did not have that massive proliferation of citizen scientists.”
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