Scientists discover wild baby parrots babble like human babies

Researchers have discovered that baby parrots babble to themselves, much like human babies do.

The parrots aren't just saying the avian equivalent of goo-goo-ga-ga.  Instead, they're repeating back the bird sounds they've heard before from adults and their fellow babies. 

"It's kind of a tossed salad of just about everything that the birds have heard up to that stage in their life," said biologist Karl Berg, part of the team who made the discovery. "It would be like if you just opened a dictionary and started rattling off words."

The scientists worked with green-rumped parrotlets, which, much like other parrot species, are known to be vocal learners who mimic the noises around them. The babbling noises began when the parrotlets were around 21 days old, and researchers counted 27 different calls, such as soft peeps, clicks and growling noises. 

The behaviour hadn't been seen before, mostly because baby parrots tend to do it when no adults are around, and they do it very quietly, often without even fully opening their beaks.

"Often it's the eldest nestling that's into its babbling stage and the [other babies] kind of fall asleep," said Berg, an associate professor in biology at University of Texas Rio Grande Valley.

"It's kind of sweet. It's almost like he or she sings them to sleep."

The study was published in the journal Proceedings of the Royal Society B.

Surprising discovery at a unique study site

The discovery was made at Venezuela's Masaguaral Biological Station, home to the longest ongoing study of any wild parrot population. There, spread over 14,000 acres, researchers have set up over a hundred PVC pipes to act as artificial nests, which allows them to easily monitor the birds with audio and video equipment.

It was assumed that the baby birds were silent when the parents weren't around, since they typically don't do much other than sleep and feed. But while Berg was studying the contact calls that the baby birds made when their parents returned to the nest, he happened to catch a recording of this babbling audio.

"It seems kind of obvious that they're sort of playing, if you will, and practising and exploring, exploring with their vocal cords and their bills and their tongue," said Berg. "I suspect it requires some practice before they start doing it right."

Parrots as a model for human vocal learning

Berg loves working with parrots because of what they can teach us about humans — and in particular, the mechanisms at play when develop language skills.

"The more we study them, the more things we run across that I really do think help explain in a broader sense why they're considered the most accomplished of nonhuman vocal linguists."

Songbirds have also been known to babble, but Berg says that behaviour only exists in males. Also, babbling kicks in during the songbird's puberty phase, which indicates it's motivated by sex hormones.

In humans, previous research has found that it's our stress hormones, such as cortisol, which play a role in language development as babies.

"Babbling typically begins in human infants at six months, and language kicks in at 12 months. And obviously, the gonads are not at all developed. There's no circulating sex hormones like testosterone or estrogen at that stage in life. There's no point in it," Berg said.

"What a human baby is interested in at that stage is getting food and fighting off disease. And their stress hormones play a very important role." 

To find out whether stress hormones play a role in parrotlet babbling, Berg and his colleagues fed the parrotlets small amounts of the stress hormone corticosterone and found they made twice as many unique babbling noises.

Berg now aims to examine the relationship between stress and babbling further by introducing the hormones at different stages in the bird's development.

"Stress hormones can aid memory …. It can also make you sharp and aware and better able to retrieve from memory during development. It plays an especially important role in developing the brain," he said.

He adds that stress may get a bad reputation, but is critical for many essential functions.

"A famous endocrinologist once said, it's not stress that kills you. It's stress that keeps you alive."

Produced and written by Amanda Buckiewicz.