A new bird song is spreading like a wildfire among Canadian white-throated sparrows, on a scale never seen before by scientists.
Birds seldom change their joyous little tunes, and when they do, it’s generally limited to the local setting, where small song variations basically turn into regional dialects. New research published yesterday in Current Biology describes an extraordinary exception to this rule, in which a new song sung by white-throated sparrows is spreading across Canada at an unprecedented rate. Also, the new song seems to be replacing the pre-existing melody, which dates back to the 1960s.
Birds sing to mark their territories and attract potential mates. Traditionally, white-throated sparrows in western and central Canada sing a song that is distinguished by its three-note ending. The new song, which probably started as a regional dialect sometime between 1960 and 2000, features a distinctive two-note ending, and is taking the sparrow community by storm. What makes the new ending so viral is a mystery to the authors of the study, led by Ken Otter of the University of Northern British Columbia.
“These songs are learned; otherwise, new variants would not emerge or spread,” Otter told Gizmodo. “Where it started it may have been a single bird, but then others learned it and would train tutors for other birds. It would not spread from a single bird.
The new song, which can now be heard from British Columbia to central Ontario at a distance of more than 1,900 miles (3,000 km), ran from 2000 to 2019, according to research. The old tune, with its very loud musical trio, is now in danger of extinction.
The contributions of scientific citizens were an integral part of the research. Field recordings of white-throated sparrows were uploaded to an online database called eBird, allowing Otter and his colleagues to track the spread of the new doublet in time and space.
“Citizen scientists played a key role as the songs they recorded and made available expanded the spatial reach of the study. We could never have covered this kind of distance if it was just us collecting songs, “said Otter. “Song libraries have expanded massively in the past five years, with eBird allowing people to upload recordings, not just observations.”
The results showed that the song probably originated west of the Rocky Mountains, where it has been a huge hit for years, and has spread steadily and quickly eastward. By 2014, all white-throated sparrows in Alberta were singing the new double, with sizable populations of birds in Ontario also singing the merry tune.
The sparrow’s wintering spots seem to be a key factor in explaining how the new melody has spread so rapidly in such a large geographic area. Juvenile males arrive in their hibernation zones and mix with sparrows from different parts of the country. Here, impressionable young birds pick up the new tune and carry it back to their mating grounds, where other sparrows pick it up. Saying that the new tune is going viral is a pretty accurate assessment.
To test this theory, that western and eastern sparrows share wintering areas, Otter’s team linked geolocators to wild sparrows. Their results showed that this is the case. Otter said a similar trend is occurring among white-throated sparrows in the United States, “but most of their breeding area is in the boreal forest of Canada,” he said.
Why the new bird song is so compelling remains an unanswered question. It doesn’t seem to be giving male birds a territorial advantage over their cohorts, so it could be that female birds are attracted to songs that are unfamiliar to them. But, as Otter pointed out, variants cannot be too unknown.
“It seems that these sparrows may prefer to adopt slightly new song variants instead of the common song. However, it seems to have to match some sort of template, since every once in a while you come across men who sing variants that are not doublets or triplets, but these other variants don’t seem to capture, “Otter told Gizmodo.” So So there must be some restrictions on what they will accept. “
In fact, it seems that the sparrows are already getting tired of the new song. According to Otter, it was recently replaced by a new variant in Prince George, British Columbia, where the doublet is suspected to have originated. He has been in this area for over 20 years, “which is why birds no longer consider it novel,” which explains “why a new type of song is emerging.”
The researchers hope to further study these bird songs to see if female sparrows are really responding to new melodies, in a process that seems to demand continuous musical innovations among these remarkable birds.
Featured Image: Scott M. Ramsay
