Researchers found that the young birds keep practising and listening to their own sounds, fixing any mistakes that occur, until eventually they can sing like their elders.
Scientists studying how songbirds stay on key developed a statistical explanation for why some things are harder for the brain to learn than others.
"We've built the first mathematical model that uses a bird's previous sensorimotor experience to predict its ability to learn. We hope it will help us understand the math of learning in other species, including humans," said biologist Samuel Sober.
Sobera and Michael Brainard of the University of California found that adult birds correct small errors in their songs more rapidly and robustly than large errors,
Just like humans, baby birds learn to vocalise by listening to adults. Days after hatching, Bengalese finches start imitating the sounds of adults.
"At first, their song is extremely variable and disorganised. It's baby talk, basically," Sober said.
Young birds, and young humans, make a lot of big mistakes as they learn to vocalise. As birds and humans get older, the variability of mistakes shrinks. One theory contends that adult brains tend to screen out big mistakes and pay more attention to smaller ones.
"To correct any mistake, the brain has to rely on the senses. The problem is, the senses are unreliable. If there is noise in the environment, for example, the brain may think it misheard and ignore the sensory experience," Sober said.
The link between variability and learning may explain why youngsters tend to learn faster and why adults are more resistant to change.
"Whether you are an opera singer or a bird, there is always variability in your sounds.
"When the brain receives an error in pitch, it seems to use this very simple and elegant strategy of evaluating the probability of whether the error was just extraneous 'noise,' a problem reading the signal, or an actual mistake in the vocalisation," Sober said in a statement.
Researchers wanted to quantify the relationship between the size of a vocal error, and the probability of the brain making a sensorimotor correction. The experiments were conducted on adult Bengalese finches outfitted with light-weight, miniature headphones.
As a bird sang into a microphone, the researchers used sound-processing equipment to trick the bird into thinking it was making vocal mistakes, by changing the bird's pitch and altering the way the bird heard itself, in real-time.
The study was published in the Proceedings of the National Academy of Sciences (PNAS).
