Noisy environments make young songbirds shuffle their tunes

Jun 19, 2012

iPod owners aren't the only ones who frequently shuffle their favorite tunes. Baby songbirds do it, too, a new study shows.

A baby prefers to learn the clearest versions of songs he hears and uses them to build his personal playlist for life. As a result, noise, from nature and humans, influences which songs a bird learns to sing and can create lasting changes to his species' top tunes, the study's results suggest.

"There's been an enormous amount of interest in how anthropogenic factors affect the channels animals use for communication and in particular how human noise affects birdsong," said Duke University biologist and study co-author Steve Nowicki. "As far as we know, this is the first study that can link noise to cultural evolution of ."

The team designed the study to test a 30-year-old hypothesis suggesting that young birds memorize and later sing the clearest songs they hear during their critical learning period. In the experiment, Nowicki and his collaborators collected nine male, swamp-sparrow and hand-raised them in a soundproof room.

Twice a day for 12 weeks, the birds heard recordings of 16 types sung by of their species. Eight song types were degraded, or noisy, by being broadcast across a typical sparrow territory of 25 meters and then re-recorded. The other eight were clean copies of similar-sounding, but different songs. When the birds later matured and began to sing, they only repeated the clear songs.

"It wasn't too surprising that the preferred them," said Duke behavioral ecologist Susan Peters, lead author of the study. "What is exciting is how clear-cut the results are. All of the birds learned clear songs and none learned any of the degraded songs," she said.

The results appeared online June 20 in the journal Biology Letters.

This "simple" but "elegant" experiment "says a great deal about how birds put to use their extraordinary ability to hear small-time differences," said Eugene Morton, a biologist at York University in Canada who was not involved in the study.

The birds use this ability to learn songs that transmit through their habitat with the least amount of degradation. "In this way, the birds themselves reject songs less well suited to their environment," an example of cultural selection, Morton said.

Scientists consider the song shifts to be selected culturally, rather than naturally, because the songs are learned, not innate.

"This is important because cultural selection can happen more rapidly than natural selection," Peters said. "It helps to explain why birdsong is so diverse," and shows evidence that song variation depends on the bird's habitat.

She added that noise from cities and humans would have the same effect on song selection. "We already knew that some can adjust some features of their song when confronted with anthropogenic noise, and now we know that this may have an impact on cultural transmission of their song," she said.

If naturally noisy songs are less desirable to learn, then songs shaped by human noise are probably less likely to be passed down and learned generation after generation. "Who would have thought that a swamp sparrow song might be affected by human activity?" Peters said.

Explore further: Two new species of yellow-shouldered bats endemic to the Neotropics

More information: "Songbirds learn songs least degraded by environmental transmission." S. Peters, E. Derryberry, and S. Nowicki. 2012. Biology Letters. doi/10.1098/rsbl.2012.0446

Related Stories

Sparrows change their tune to be heard in noisy cities

Apr 02, 2012

Sparrows in San Francisco's Presidio district changed their tune to soar above the increasing cacophony of car horns and engine rumbles, details new George Mason University research in the April edition of ...

It takes two to tutor a sparrow

Oct 21, 2009

(PhysOrg.com) -- It may take a village to raise a child, and apparently it takes at least two adult birds to teach a young song sparrow how and what to sing.

Recommended for you

Offspring benefit from mum sending the right message

6 hours ago

(Phys.org) —Researchers have uncovered a previously unforeseen interaction between the sexes which reveals that offspring survival is affected by chemical signals emitted from the females' eggs.

Lemurs match scent of a friend to sound of her voice

21 hours ago

Humans aren't alone in their ability to match a voice to a face—animals such as dogs, horses, crows and monkeys are able to recognize familiar individuals this way too, a growing body of research shows.

User comments : 0

More news stories

Adventurous bacteria

To reproduce or to conquer the world? Surprisingly, bacteria also face this problem. Theoretical biophysicists at Ludwig-Maximilians-Universitaet (LMU) in Munich have now shown how these organisms should ...

Revealing camouflaged bacteria

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...

How kids' brain structures grow as memory develops

Our ability to store memories improves during childhood, associated with structural changes in the hippocampus and its connections with prefrontal and parietal cortices. New research from UC Davis is exploring ...

Gate for bacterial toxins found

Prof. Dr. Dr. Klaus Aktories and Dr. Panagiotis Papatheodorou from the Institute of Experimental and Clinical Pharmacology and Toxicology of the University of Freiburg have discovered the receptor responsible ...