Baby Parrots Babble Like Baby People

Babbling is common in a wild population of parrotlets in Venezuela and closely resembles babbling in human infants, which is an early stage of the vocal language learning process

© Copyright by GrrlScientist | @GrrlScientist | hosted by Forbes

Before learning to speak, human babies go through a vocal stage known as babbling, which is a well documented part of the vocal language acquisition process. Basically, babbling is how an animal practices its vocalizations — by listening to and mimicking the adults they hear around them.

Although most animals are born knowing what they should sound like, there is another animal that learns its vocalizations by mimics what it hears: parrots. Curiously, although parrots have been widely celebrated for their vocal learning abilities for thousands of years, a babbling phase had never been reported in nestling parrots.

But now, a new study shows that baby parrots do babble. This is probably not news to anyone who lives with a parrot — even Alex the grey parrot, who was famous for his ability to mimic, to talk and to understand what he was saying, frequently babbled (ref). But what makes this new study truly notable is that these babbling baby parrots are green-rumped parrotlets, Forpus passerinus, a different species from Alex — and they are wild. This indicates that babbling is a widespread and natural developmental process in parrots.

What is a parrotlet?

Parrotlets are a group of the smallest of all New World parrot species and they comprise three taxonomic genera: Touit (eight species, none of which have been successfully kept in captivity), Nannopsittaca (two species), and Forpus (nine species). The Forpus parrotlets are the most familiar parrotlets in the US pet trade, where they often are known collectively as ‘pocket parrots’.

As parrots go, the green-rumped parrotlet is really tiny — they are about the size and color of a leaf and they weigh less than 5 US nickels. These tiny parrots occur throughout north-eastern South America, from Venezuela to Brazil.

Green-rumped parrotlets are primarily lime-green with grey-green on the nape of the neck, dark eyes and a horn-colored bill and feet. Males and females can be visually distinguished: males have purple-blue primaries, secondaries and wing coverts, and bright turquoise on the leading edges of their wings. Females lack these blue feathers but they do have more extensive lime-green on their heads.

In the wild, these tiny parrots flock into groups ranging from five to 100 individuals. Like most parrots, they nest in tree cavities and feed on a variety of seeds as well as berries, buds and fruits. Currently, green-rumped parrotlets are widespread, typically wandering widely through a variety of open semi-arid lowland habitats in search of food. Even though they are common, their populations are declining, thanks to deforestation.

What is vocal babbling?

“It’s kind of a tossed salad of just about everything that the birds have heard up to that stage in their life”, said behavioral ecologist Karl Berg, an associate professor at the University of Texas Rio Grande Valley (UTRGV). “It would be like if you just opened a dictionary and started rattling off words.”

Vocal babbling has been reported in a few other species (notably, in human infants), but we know most about this behavior from our songbird studies. For several decades, a number of songbird species have served as important model systems for understanding the neurobiology and physiology underlying how complex vocal communication is learned from adult templates.

In songbirds, the developmental stress hypothesis proposes that song is an honest signal of a male’s quality because chronic stress in early development has deleterious effects on brain structure and learning ability. Stress in birds is physiologically mediated by corticosterone. Studies have shown that feeding tiny doses of corticosterone to nestling songbirds limits their vocal learning process later when they undergo puberty (ref) — and it is this early exposure to stress hormones that provides a female songbird with important information about a potential mate’s developmental history and overall quality (ref, ref & ref).

“The endocrine system helps internalize environmental information,” Professor Berg explained. “That’s important for a lot of things in life and learning is one of them.”

But songbirds are very different from human infants because male songbirds babble only when they reach puberty, indicating that this behavior is triggered by sex hormones.

“Babbling typically begins in human infants at six months, and language kicks in at 12 months”, Professor Berg reported. “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 for it.”

“What a human baby is interested in at that stage is getting food and fighting off disease”, Professor Berg added.

Vocal babbling identified in wild parrots using modern AV equipment

Why had no one heard vocal babbling in parrots before now? There are several reasons: first, parrots nest in dark cavities usually located very high up a tall tree. Second, baby parrots tend to babble quietly when no adults are around, often without even fully opening their beaks. (Sometimes, they don’t open their eyes, either.) These factors explain why vocal babbling in parrot nestlings has not been identified previously, and has not been investigated by researchers (although this behavior is not new to those who handfeed baby parrots — they just didn’t know what it was, nor its significance).

To better understand vocal babbling in baby parrots, avian ecologist Rory Eggleston, a biology graduate student at UTRGV, collaborated with his thesis advisor, Professor Berg, and an international team of scientists to study vocal babbling development in parrots.

Together, Mr Eggleston, Professor Berg and their collaborators studied a wild population of green-rumped parrotlets during two breeding seasons (2017 & 2018) at the Hato Masagüaral research center, a 7000 hectare (more than 14,000 acres) cattle ranch and field research station in the State of Guárico in Venezuela. This research center hosts the longest ongoing study of wild parrots in the world, which started in 1988. On this site, more than 10,000 individual parrotlets wear unique combinations of colored leg bands so they can be identified and monitored from a distance.

“[T]oday when you walk through the study site, you can take out your telescope and identify individuals by their bands and look up their identities, their ages, and their relatives”, Professor Berg stated.

The habitat at the Hato Masagüaral consists of tropical savannah, gallery forest and, because parts of it are still a working cattle ranch, pastures. Livestock and other domestic animals are kept under control — more or less — to minimize their impacts upon wildlife and their habitats.

Scientists maintain 106 PVC pipes as artificial nest cavities, which allows them to easily monitor nesting parrots with audio and video equipment. Parrotlet nests are checked every three days during the breeding season (June–December) to determine egg-laying, hatching and fledging dates.

For this study, eggs and nestlings were each uniquely marked with a non-toxic felt-tip marker before they were given their own unique color combinations of leg bands at 25 days of age. Because parrotlets have sexually dichromatic plumage patterns that first become visible at 15 days of age, researchers can identify sex whilst the chicks were very young.

Mr Eggleston, Professor Berg and their collaborators installed camcorders in a dozen nests and recorded the parrotlet chicks. They analyzed these recordings and found that the nestlings began babbling at 21 days of age and the complexity of the sounds they produced increased dramatically over the ensuing week.

The team discovered that babbling baby parrots articulated a collection of quiet sounds, usually without opening their beaks and often when their siblings were asleep and their parents were absent. Like a human baby babbling alone in its crib, these baby parrots were not communicating with anyone else. They were apparently just … practicing.

“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”, Professor Berg said. “I suspect it requires some practice before they start doing it right.”

Do all of the parrotlet babies in a nest babble?

“Often it’s the eldest nestling that’s into its babbling stage [first] and the [younger babies] kind of fall asleep”, Professor Berg said. The younger parrots join the babbling chorus as they get older.

“It’s kind of sweet. It’s almost like he or she sings them to sleep”, Professor Berg added.

Spectrographs of the chicks’ babbling revealed as many as 27 distinct sounds, including soft peeps, clicks, and growls — sounds that resembled the adult parrotlets’ warbling, begging, alarm and contact calls.

“It was quite a surprise: The nestlings know the full repertory of adult vocalizations”, Professor Berg remarked.

Stress hormones led to larger vocal repertoires in parrots

Previous studies found that stress hormones play an important role in language development in human babies. This differs from the process of song learning in songbirds, which is supported by sex hormones. But what about parrots: are they like humans or are they like songbirds?

To learn whether and how stress hormones might affect baby parrot babbling, Mr Eggleston, Professor Berg and their collaborators fed a small dose of corticosterone (CORT), an avian stress hormone, to one nestling in each of twelve study clutches for one week during their first week of babbling. They then recorded the nestlings’ utterances and analyzed them.

After treatment with corticosterone, the team found that nestlings of both sexes had increased vocal repertoires — producing twice as many unique babbling noises as chicks that did not receive any stress hormones (Figure 3).

Thus, Mr Eggleston, Professor Berg and their collaborators concluded that stress hormones at an early age have powerful organizational effects on the neural pathways underlying language development in baby parrotlets and these hormones resulted in a universal increase in their repertoires. This is the opposite scenario to that seen in songbirds, where stress hormones reduce vocal learning repertories.

This study also highlighted an intriguing parallel in language learning between parrots and humans: cortisol, which is the mammalian stress hormone, has been shown to have similar effects in baby humans (ref).

Stress is essential for many important functions

Stress gets a bad reputation in human society, but it is essential for many important biological functions.

“Stress hormones can aid memory”, Professor Berg explained. “It can also make you sharp and aware and better able to retrieve from memory during development.”

And, as we’ve just seen, stress hormones play an especially important role in developing the brain.

Professor Berg plans to continue studying the impacts of stress on babbling in parrotlets because these little parrots could help us learn more about how humans develop our own language learning skills. Currently, Professor Berg and his team are working towards better defining when stress hormones are most important during development by introducing the hormones at different stages in a young parrot’s life. Other interesting questions include: what are the effects of stress hormones on a parrot’s siblings? For example, if one nestling is given corticosterone, did all its siblings’ babbling increase? Do some parrot siblings in the birth order benefit more than others from additional corticosterone? Do parrots with a lot of siblings develop a larger vocal repertories than those with few siblings? What happens to a parrot’s vocal learning capabilities if it lacks siblings?

This interesting little study emphasizes how humans and parrots have managed to evolve very similar language learning systems, where stress hormones serve comparable — and powerful — roles, despite the more than 600 million years of evolution that separate us.


Rory Eggleston, Nurialby Viloria, Soraya Delgado, Astolfo Mata, Hilda Y. Guerrero, Richard J. Kline, Steven R. Beissinger and Karl S. Berg (2022). Vocal babbling in a wild parrot shows life history and endocrine affinities with human infants, Proceedings of the Royal Society B: Biological Sciences 20220592 | doi:10.1098/rspb.2022.0592


NOTE: This piece is © Copyright by GrrlScientist. Unless otherwise stated, all material by GrrlScientist and hosted by Forbes is © copyright GrrlScientist and is intended only to appear on Forbes. No individual or entity is permitted to copy, publish, commercially use or to claim authorship of any information contained on this website without the express written permission of GrrlScientist.

You may also like...