She’s not the real Dr. Doolittle. She is an ecologist from Christchurch, New Zealand who specializes in a little-known field of science: bird dialects.
While some birds are born to sing from the inside, many need to be taught how to sing by adults – just like humans. These birds can develop a regional dialect, which means their songs sound a little different depending on where they live. Imagine the accents of Boston and Georgia, but for birds.
Just as a local language can make it easier for a person to fit in, speaking a bird dialect can increase the chances of finding a partner. And, more sinisterly, just as human dialects can sometimes disappear as the world globalizes, bird dialects can take shape or get lost as cities grow.
The similarities between human language and bird song are not lost on Molles – or on her fellow bird dialect experts.
“There are wonderful parallels,” said American ornithologist Donald Kroodsma, author of The Bird for Curious Naturalists: Your Listening Guide. “Culture, oral traditions – it’s all the same.”
The first experts in the bird dialect
For centuries, the song of birds has inspired poets and musicians, but it was not until the 1950s that scientists began to pay attention to bird dialects.
Scientists put birds in soundproof chambers in the 1960s and 1970s to see if they could sing their songs, ornithologist David Luther said.
Scientists have found that some birds – those who learn their songs – cannot sing at all. “They just kept blabbering on like a baby all their lives,” he said. These birds are known as “real bird songs”. In other birds, singing was innate. “When they come of age, they could just sing the perfect song without a problem.”
When birds copy adults, scientists have discovered, sometimes they make mistakes. This error is in turn copied by other birds and a local dialect develops. This means that dialects can only exist in real bird songs, because they have a “learned oral tradition,” says Kroodsma.
Dialects can be created even after the birds adapt to the local environment, said American ornithologist Elizabeth Derryberry. Birds that hear better can get along better, which means their song is more likely to be passed down from generation to generation.
It is linked to the idea developed by Bernie Krause, the founder of sound ecology, that animals make sounds in a variety of terrains so that they can be heard.
Some dialects change quickly – even within the breeding season. Other birds have been sticking to their dialects for decades. When Luther researched the dialects of the white-crowned sparrow from San Francisco – a common bird in North America – he found that some dialects had not changed at all in 40 years.
Dialects and socializing (in birds)
For something that is often the result of copying problems, dialects can be very useful.
According to Molles, birds communicate for two reasons: Either they are trying to discover their neighbor, or they are trying to attract females. “Unfortunately, nothing very poetic,” she stops.
When it comes to defending territory from other birds of the same species that are not locally in the area, knowledge of the local dialect allows for more complex interaction. Mimicking a song with a note is considered aggressive towards birds, so a wider repertoire means the bird can prevail without escalating interaction in an argument.
Knowing the local dialect is also useful when it comes to finding a romantic partner.
In many species the male sings. According to Molles, females prefer the familiar dialect – this suggests that male birds know the local area, the territory, and not just “someone who passes by.” Some birds are bilingual or even trilingual – perhaps because they grew up around different local dialects. When they mate, they will choose to sing the local dialect wherever they choose to settle, Luther said.
But the fact that there is no real dialect is not an insurmountable obstacle.
Kroodsma gave the example of the Prague leader in Massachusetts, where he is also based, and who returns every year for the past few years. Although the bird has a very atypical song, it attracted females and raised babies every year.
“Someone might say, ‘There, there’s the news effect, a male with a very different song and all the females think it’s sexy,’ he said. ‘But that’s just a wild assumption.’
This is something that researchers are thinking about in places like New Zealand, where endangered birds are sometimes reintroduced into new areas. Researchers want to be sure that if they reintroduce birds, they will reintegrate, even if they do not have the right dialect.
According to Molles ’experience, this usually works if a group of birds is reintroduced, so they have other birds with an unusual dialect.
She was involved in the reintroduction of the Kokak – a native gray-blue bird with an invited violin – into the New Zealand area hundreds of miles away from where they were born. At first, the newcomers could deal with each other, she said. But they could be integrated in the future. The descendants of the newcomers are likely to begin crossbreeding with the descendants of the native population who grew up in the knowledge of both the new and local dialects.
“A female doesn’t necessarily have to look for someone who matches a song sung by her father,” Molles said. “She finds a partner that fits the area where she wants to settle – he’s not just some bird with an unusual ball that may not belong there.”
How people change the dialects of birds
As cities around the world fell into Derryberry, a number of questions arose.
Over the years, birds began to sing in a higher tone in cities to be heard in quiet traffic and construction. What would happen to the birds if the cities fell silent? If it were calmer, would the new generation of birds sing in lower tones? And next year, when it came time to grow, would you hear when the city noise came back?
He is still working on answers to these questions, but Kroodsma is skeptical that a short period of silence could be long enough to have any impact on bird dialects.
Although our coronavirus stop this time has not changed bird dialects, it is worth thinking about how we generally shape – and destroy – bird dialects. Something a bit like a transmission line could be enough to divide the bird population and lead to the creation of new dialects, Kroodsma says.
Molles remembers finding historical footage of the population of the native Kokab which he now lacks.
“Some of the songs on those tapes were just amazing – weird metallic sounds you would never have guessed created by a bird,” she said.
“It was pretty depressing to hear some of them and think. We’ll never hear that again.”
Design and graphics by Jason Kwok and Natalie Leung. Development by Marco Chacón.
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