You can teach an older parakeet a new language, but will he want to learn it? New research from New Mexico State University says it may depend on his ability to make new friends.

In humans, the ability to learn new languages starts to decline as we hit our twenties and as we continue to age, other language abilities also decline. NMSU researchers are using parrots as a model for understanding this sort of decline, both behaviorally and neurologically.

Their results were published June 14 in the "Proceedings of the Royal Society B," the Royal Society's flagship biological research journal. NMSU biology master's student Bushra Moussaoui is the lead author on the paper titled "Evidence for maintenance of key components of vocal learning in ageing budgerigars despite diminished affiliative social interaction."

Co-authors include NMSU biology Professor Tim Wright, Samantha L. Overcashier, a former undergraduate at NMSU, Gregory M. Kohn from the University of North Florida in Jacksonville and Marcelo Araya-Salas from the Universidad de Costa Rica.

"Many parrots are thought to be open-ended learners, meaning they can learn throughout their life," Wright said. "We don't know the extent to which there might be some sort of decline in the ability of adult parrots to learn. So, Bushra (Moussaoui) set out to ask this question in her master's thesis."

The budgerigar is a type of parrot commonly bred in captivity as a pet store parakeet and is easily available. It is an open-ended learner that develops new contact call types that are shared with social associates upon joining new flocks, so Moussaoui decided it would make a good subject for measuring the effects of aging on vocal learning ability.

For the study, the group formed captive flocks of four adult males, previously unfamiliar with each other in the same age class ­­– characterized as either 'young adults' age six months to one year old or 'older adults' three years old or older. They tracked changes in contact call structure in these flocks of strangers and correlated them with the birds' social interactions over time.

Each budgerigar typically has three or four contact calls and will share those contact calls with some of the other individuals within the group. But none of the birds in the study knew each other. Researchers followed the birds for three weeks, conducting video recording of them daily to monitor types of social interactions such as kisses and grooming, or pecking and kicking each other as well as the birds' vocalizations.

"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," Wright said.

Researchers mapped all the birds' calls onto what they call 'acoustic space,' where each call is at a different point and the closer calls are together, the more similar they are. Distinct clumps of calls represent different call types. The group mapped the changes over time in that acoustic space and discovered the diversity of each individual's vocal repertoire.

"Older birds didn't occupy much acoustic space," Wright said. "They didn't learn as many new things as younger individuals. That may be because they were trying to match the calls of fewer individuals.

"When we looked at their social relationships, we found the social networks in the older birds were much sparser," Wright said. "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."

The older birds, however, did display equivalent levels of vocal plasticity, which is the ability to modify existing calls, and vocal convergence, which is the ability to match other's calls, compared to younger birds. This suggested that many components of vocal learning are largely maintained into later adulthood in an open-ended learner. 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," Wright said. "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."

The full article can be seen at https://newsroom.nmsu.edu/news/nmsu-researchers-study-older-parakeets-to-find-out-whether-learning-declines-with-age/s/4034de3f-320c-4420-a8dc-1f6afb681bf1