The steady tapping of a woodpecker as it drills into a tree for food or a nest site and drums to attract a mate is an unmistakable sound. Between their distinctive sound and the brilliant red feathers on some species of woodpeckers, these birds found all over the world stand out among other flighty, feathered creatures.
But this unique sound could be controlled by a special area of the brain. A team of researchers led by Matthew Fuxjager at Brown University and Eric Schuppe at Wake Forest University have found regions in the woodpecker forebrain which have previously only been associated with both vocal learning in animals and language in humans. Their study, published today in the journal PLOS Biology, suggests that the activity in this region of a woodpecker’s brain is associated with tree drumming, instead of vocalization like in other animals.
“I was really interested in the origins of drumming and how the brain controls it, and was shocked that woodpeckers had specialized brain regions to control drumming behavior,” Fuxjager, an associate professor of ecology tells Popular Science.
Fuxjager is interested in the the evolution of display behavior, and how the brain, muscle, and hormone systems in an animal evolve so that animals perform new displays or unusual things. “At a mechanistic level, very few people have explored how the physiological and neurobiological systems in those animals evolved to support that behavior. So the idea that you’d have these specializations in the brain to support that behavior is really wild,” he says.
Human language and birdsong share many characteristics. They both require complex muscle coordination, are learned at a young age, and are controlled by special regions of the brain. Songbirds and humans also both express a marker gene in these regions called parvalbumin (PV) which helps move calcium around in the cell. “It is a protein that is expressed in lots of different cells throughout the body. I’ve studied parvalbumin and muscle and it’s also an in brain tissue,” Fuxjager explains.
The team checked the PV for gene expression in ducks, flamingos, penguins, and woodpeckers . They found that woodpeckers do contain these special regions of the brain that make PV and that these areas are similar in both number and location compared to many of the forebrain nuclei that control both song production and learning in songbirds.
During open field tests with woodpeckers, the team discovered that the behavior that triggered brain activity in these regions was their signature rapid drumming, and not their vocalizations (or songs). Woodpeckers use the drumming to defend territories just like birdsong does, and it requires rapid and complex motor movements, and must be adaptable when birds compete with each other.
Finding this system for non-vocal communication that is neurologically and mechanically similar to the birdsong system can help researchers understand how the brain has changed to preform different functions. It also paves the way for a greater understanding of bird and animal communication and how it is learned, which gives scientists more knowledge of the inner world of animals and their evolution.
“There’s two things that I really want to do after this,” says Fuxjager. “I want to test whether woodpeckers learned any component of their drumming, and the fact that they have these brain regions would suggest that that’s possible. The second thing I want to look at is whether the evolution of these regions in any kind of component of their their morphology. So, what the cells look like, what the brain regions look like, and whether that tracks to any differences or changes in drumming across the woodpecker family.”