NMSU professor, alumnus discover link between vocal learning of hummingbirds and humans

https://newscenter.nmsu.edu/Articles/view/13907/nmsu-professor-alumnus-discover-link-between-vocal-learning-of-hummingbirds-and-humans?fbclid=IwAR0bo5ftE6rgzqo2CrVVU3gGj4xX8CAUJCoBx91NA1VKTjEd37f773lvfDY

Marcelo Araya Salas who earned his doctorate in biology from NMSU in 2015 led the study funded by the National Geographic Society. Salas worked with Department of Biology professor Timothy Wright conducting the study, which formed the basis for a paper published in the research journal “Proceedings of the Royal Society B.” Salas’ research also was featured as part of the PBS documentary “Super Hummingbirds II.”

“Marcelo is an extraordinary field scientist, and he figured out how to capture, record, and really observe these hummingbirds,” said Wright. “My main role as his mentor was basically just helping him hone the questions he wanted to ask.”

Chief among these questions for Sales was why hummingbirds utilize distinct vocal and visual displays in the process of attracting a mate (also known as “lekking.”)

“We scientists have known for a while that hummingbirds are able to socially learn their songs,” said Sales, “and that that was a clear indicator of vocal learning. So we wanted to explore the relationship between that and the visual displays they make.”

“There’s a hypothesis that brain regions devoted to vocal learning have evolved from nearby regions that support general learning ability – the ability to see other individuals do something, and copy it,” said Wright. “And if that was the case, you might predict that animals that have learned their vocalization might also learn the visual displays that they did alongside it. We studied this in a hummingbird since, in the process of mating, they utilized both vocal learning and an elaborate series of visual displays.”

But it’s not just the distinct nature of their mating rituals that makes hummingbirds a prime subject for studying vocal learning.

“Our work on vocal learning birds such as hummingbirds and parrots is motivated, in part, by trying to understand how – and why – humans have developed vocal learning,” said Wright. “Our closest relatives, chimpanzees, have very little to no examples of learned vocalizations, making it a challenging field to study directly. But we have several lineages of birds that are capable of vocal learning that we make use of for that purpose.”

In order to draw as much vocal learning data as possible from these birds, Salas worked alongside a team of field assistants in his home country of Costa Rica, where multiple lekking sites and dozen of birds were observed and studied for hours at a time. Salas estimates more than 2,000 hours of video was created and sorted through for the study.

“What we found was that some aspects of visual displays vary at a very small geographic scale,” said Salas. “This strongly suggests those aspects are socially learned, which means that they copy some aspects of their displays from what they see other individuals doing.”

“In some ways this is a surprising result, in that no one has really described this variation before,” said Wright. “But as people understand better how the bird brains are arranged for vocal learning, there seems to be more and more similarities with how the human brain is arranged. Birds have proven to be the best model for understanding vocal learning in humans.”

In order to get a grander correlation between hummingbird vocal learning patterns and human ones, Wright notes that further research must be done on the actual brain activity of the birds. Salas is currently in Costa Rica working on a postdoctoral fellowship at the University of Costa Rica, where he continues his hummingbird research. Earlier this year, he attended the annual meetings of the Animal Behavior Society in Chicago where his poster describing how the learned songs change over time was awarded the Founder’s Memorial prize for the best poster by a graduate student or post-doc.

“To me the field work and the statistical analysis -- the “eureka!” part – is always the most exciting. Field work is fun, but also a bit challenging, as you never know if you are going to get good data. The stats part is always the climax of the research, and its rewarding to see the research be observed and read after the fact.”