Language learning becomes more challenging for people as we age. Children learn languages easily, but this facility begins to decline when we reach our twenties and beyond. Why?
To better understand the nuances of language learning in humans, a team of scientists at New Mexico State University (NMSU) are studying vocal learning in budgerigars. This team of researchers recently reported an interesting finding: learning new vocalizations may depend on an individual budgerigar’s ability and motivation to make new friends.
“I think a much more concise title [for this study] would be ‘You Can Teach an Old Bird New Tricks, But Only If They Want to Learn’,” Timothy Wright, a Biology Professor at NMSU said in a statement. Professor Wright’s areas of expertise include the evolution of vocal learning and communication signals amongst birds, with a particular focus on parrots because their well-developed learning abilities provide interesting contrasts in behavior, ecology, and life history patterns to better-studied songbirds.
“[O]ur study was one in which we contrasted the ability of young adult budgerigars and old adult budgerigars to learn new vocalizations when put into a new social situation,” Professor Wright explained.
Budgerigars, Melopsittacus undulatus, commonly known as “budgies,” shell parakeets or common parakeets, are small, long-tailed parrots that are common in pet shops around the globe. Native to open scrublands, open woodlands, and grasslands throughout most of Australia, these green-and-yellow parrots are highly gregarious and nomadic, often traveling in massive flocks.
Captive-bred budgerigars come in several sizes and in a veritable rainbow of colors and color patterns. Despite this, it is easy to identify the sex of adults because their ceres (that waxy fleshy covering at the base of the upper beak) are color-coded: blue for boys and rust for girls.
Budgerigars are also extremely talented mimics. A male budgerigar named Puck holds the world record for the largest vocabulary of any bird, at 1,728 words. My personal favorite “talking” budgerigar, Disco, was an internet sensation, who had his own YouTube channel (here) featuring hundreds of his chatty videos that collectively attracted more than 24 million views. Disco, like many budgerigars, learned new vocalizations throughout his life.
“Many parrots are thought to be open-ended learners, meaning they can learn throughout their life,” Professor Wright observed. “We don’t know the extent to which there might be some sort of decline in the ability of adult parrots to learn.”
We do know that budgerigars learn new calls when they join a new flock, as happens often in the wild. For this reason, lead author of the study, Bushra Moussaoui, thought these small parrots would make good subjects for her Master’s Thesis where she would measure the effects of aging on vocal learning ability.
For the study, Professor Wright, Ms Moussaoui and their collaborators created new flocks of budgerigars comprising four adult males who had never met each other before (Figure 1). These budgerigars were classified either as either ‘young adults’ — six months to one year old — or ‘older adults’ — three years old or older.
“[W]e had maintained separate populations of birds — old birds and young birds — so we could draw one individual from each of these populations to create these novel groups,” Professor Wright elaborated.
Each budgerigar typically has three or four contact calls and shares them with at least some of the other members within its group. But none of the birds in this study had met each other, so they didn’t yet know each other’s contact calls. Would there be an age difference in how quickly they learned contact calls from others in their new flock?
Professor Wright, Ms Moussaoui and their collaborators tracked changes in contact call structure for each individual in these flocks of strangers over three weeks and correlated them with the birds’ social interactions.
To track these changes in contact calls, the parrots’ contact calls were recorded daily.
“We would take one bird out and put it in an acoustic isolation chamber with a plexiglass front so it could see the other birds, but couldn’t hear them very well and as they tried to call back and forth, we would record their calls,” Professor Wright said.
The researchers then analyzed the call frequencies, durations, and pitches from each budgerigar and mapped these data onto an ‘acoustic space,’ (Figure 1b). Each call is represented by a different point and the closer the points are to each other, the more similar they are. Distinct clumps of points represent different call types.
These acoustic space maps of vocal changes revealed how birds who originated in different groups with different repertoires converged onto similar repertoires with their new flockmates.
“Older birds didn’t occupy much acoustic space,” Professor Wright reported. “They didn’t learn as many new things as younger individuals.”
Perhaps surprisingly, Professor Wright, Ms Moussaoui and their collaborators found no significant differences between young and older adults in overall levels of vocal plasticity or vocal convergence relative to baseline levels, suggesting that these aspects of vocal learning are not dependent on adult age (figure 2).
Adult age and recording block, however, did interact. Overlap with recordings of each budgerigar at the beginning of the study appears to decrease over time within young adults and remain stable over time in older adults (figure 2). Acoustic overlap with the contact call repertoire of each bird’s flockmates appears to increase over time for young adults and to decrease over time for older adults.
In addition to recording and analyzing the budgerigars’ vocalizations, the team also conducted daily video recording of the birds to monitor their social interactions to see who was sitting next to whom and how close they were sitting. Were they making new friends?
“When we looked at their social relationships, we found the social networks in the older birds were much sparser,” Professor Wright pointed out (Figure 3). “They hung out with other birds, but they didn’t spend a lot of time making new friends. That tracks with the fact that their vocal repertoires didn’t have as many new call types in them because they weren’t trying to match as many other individuals.”
These findings suggest that many components of vocal learning are maintained into later adulthood in an open-ended learner, like most parrot species. The decreased vocal diversity that researchers found in the older adults appeared to be related to sparser and weaker social bonds.
“The take home message for us is that older budgerigars make fewer new friends when stuck into a new group and they’re less likely to learn new calls because they’re making fewer new friends. They do seem to be capable of learning,” Professor Wright summarized. “They can change their calls and they can match other’s calls but they just don’t seem to be as eager to do it, perhaps because they’re just not interested in making new friends.”
So basically, budgerigars are telling us that, if we wish to speak new languages, the best way to do this is to make some friends who speak these languages and interact with them frequently.
“[I]t’s really those social interactions that drive language. Much more than, say, working with an app or a tape recorder.”
Or even working with Duolingo.
Bushra Moussaoui, Samantha L. Overcashier, Gregory M. Kohn, Marcelo Araya-Salas and Timothy F. Wright (2023). Evidence for maintenance of key components of vocal learning in ageing budgerigars despite diminished affiliative social interaction, Proceedings of the Royal Society B: Biological Sciences 290(2000) | doi:10.1098/rspb.2023.0365