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Birdsong changes much like language, study finds
Jan. 29, 2013
Courtesy of the University of Guelph
and World
Science staff
Changes in bird “culture” explain why male Savannah sparrows have altered their mating song over three decades, scientists say. Male Savannah sparrow.
(Courtesy U. of Guelph)
The researchers, who studied over 30 years of birdsong recordings,
said these changes are passed from generation to generation. It’s
“the result of cultural transmission of different song elements through many generations,”
said Ryan Norris, a biologist at the University of Guelph in Canada, who co-led the study.
The modifications resemble changes in humans' word choice and language, he went on. “If you listen to how people used to talk in the 1890s and how we talk today, you would notice major differences, and this is the result of shifts in culture or the popularity of certain
forms,” he explained. “The change in sparrow songs over time has occurred much the same
way.”
The sparrows in the study, which live on Kent Island in the Bay of Fundy, in New Brunswick, can generally sing only one song type that consists of several parts. Male sparrows learn that song early in their first year and continue to sing the same tune for the rest of their lives.
“Young male sparrows learn their songs from the birds around them,” said Norris. “It may be their fathers, or it could be other older male birds that live nearby.”
Each male sparrow has his own unique sound, said Amy Newman of the university, who co-led the study with Norris. “While the island's sparrows all sing a characteristic 'savannah sparrow
song’ ... there are distinct differences between each bird,” she said. It's basically “like karaoke versions of popular songs. It is the rise and fall in popular cover versions that has changed over
time.”
The researchers found that each song generally has three main elements. The first identifies the bird as a Savannah sparrow, the second identifies which individual is singing, and the third component is used by females to assess males.
Using graphical representations of the songs from males each breeding season, the researchers determined that, while the introductory notes had stayed generally consistent for the last 30 years, the sparrows had added a series of clicks to the middle of their songs. The birds had also changed the ending trill: once long and high-pitched, it's now shorter and lower.
Evidently “female sparrows preferred this, because males with shorter trills had higher reproductive success,”
Norris said.
Kent Island has been home to the Bowdoin Scientific Station since 1932, and the birds have been recorded since the 1980s. Individual birds are also monitored lifelong. “We know the identity and history of every single sparrow in the study population,”
said Norris. “To have 30 years of recordings is very rare, and it was definitely surprising to see such drastic
changes.” The study appears in the January issue of the journal
Animal Behaviour.
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Changes in bird “culture“ explain why male Savannah sparrows have altered their mating song over three decades, scientists say. Changes passed from generation to generation explain why the tunes keep changing, said researchers who studied over 30 years of birdsong recordings. “The change is the result of cultural transmission of different song elements through many generations,“ said Ryan Norris, a biologist at the University of Guelph in Canada, who co-led the study. The modifications resemble changes in humans' word choice and language, he went on. “If you listen to how people used to talk in the 1890s and how we talk today, you would notice major differences, and this is the result of shifts in culture or the popularity of certain forms,“ he explained. “The change in sparrow songs over time has occurred much the same way“ The sparrows, which live on Kent Island in the Bay of Fundy, in New Brunswick, can generally sing only one song type that consists of several parts. Male sparrows learn that song early in their first year and continue to sing the same tune for the rest of their lives. “Young male sparrows learn their songs from the birds around them,“ said Norris. “It may be their fathers, or it could be other older male birds that live nearby.“ Each male sparrow has his own unique sound, said Amy Newman of the university, who co-led the study with Norris. “While the island's sparrows all sing a characteristic 'savannah sparrow song,' with the same verses and sound similar, there are distinct differences between each bird,“ she said. It's basically “like karaoke versions of popular songs. It is the rise and fall in popular cover versions that has changed over time.“ The researchers found that each song generally has three main elements. The first identifies the bird as a Savannah sparrow, the second identifies which individual is singing, and the third component is used by females to assess males. Using graphical representations of the songs from males each breeding season, the researchers determined that, while the introductory notes had stayed generally consistent for the last 30 years, the sparrows had added a series of clicks to the middle of their songs. The birds had also changed the ending trill: once long and high-pitched, it's now shorter and lower. “The ending trill of the song has become shorter, likely because female sparrows preferred this, because males with shorter trills had higher reproductive success,“ Norris said. Kent Island has been home to the Bowdoin Scientific Station since 1932, and the birds have been recorded since the 1980s. Individual birds are also monitored lifelong. “We know the identity and history of every single sparrow in the study population,“ said Norris. “To have 30 years of recordings is very rare, and it was definitely surprising to see such drastic changes.“ The study appears in the January issue of the journal Animal Behaviour.