Male songbirds sing daily to build muscle

Daily vocal practice by songbirds has been shown to help keep them fit and attractive for potential mates according to a new study published in Nature Communications.

It turns out that our little feathered friends workout their vocal muscles just as an athlete exercises to build their muscles.

“Surprisingly we know very little about effects of exercise on these muscles and if they even react to training in humans,” says senior author Professor Coen Elemans from the University of Southern Denmark. “No singer will let you come even near their precious voice box.”

Singing is crucial for songbirds too.

 “They sing to impress future partners, to defend their territories and to maintain social bonds,” says lead author Dr Iris Adam, also from the University of Southern Denmark. “It has long been known that songbird singing is controlled by fast vocal muscles, but until now we only had very little knowledge if and how these muscles might respond to exercise, like our leg muscles do.”

Their research showed that vocal muscles became much weaker and slower in songbirds which didn’t use their voice boxes at all. Even when only singing is cut out, vocal muscles in the birds became 50% weaker after 7 days.

“This was very surprising,” says Dr Adam. “First that these muscles reacted so strongly, but also how incredibly fast they lost performance. Indeed, it’s use it or lose it!”

The team analysed recordings of zebra finches singing before and after vocal exercises. Though imperceptible on the first listen, the difference was clear to female zebra finches who were shown the recordings.

“Female zebra finches in the playback experiment could directly hear the difference and 75% preferred the songs from the well exercised male,” explains co-author and animal behaviour expert Dr Katharina Riebel from Leiden University in the Netherlands.

The research could help explain why birds sing so much every day.

“A lot of that singing seems out of context. They sing when they don’t need to,” says Adam.

“Our results now show that if they don’t exercise every day, their muscle performance decreases”, says Elemans. “On top of that, the lack of exercise is audible in their song and the females prefer song from exercised males.”

But the type of muscle training songbirds do is different to the exercises we might do to build our limb muscles.

“When we humans go to the gym to exercise leg and arm muscles, they typically get slower with exercise,” says co-author Professor Per Stål from the University of Umea, Sweden.

In songbirds, however, vocal muscles weaker and faster with exercise. In this way, their vocal muscles are more like those of a long-distance runner’s legs than those of a deadlift champion.

“This reversed training may be a unique feature for vocal muscles, that we think might be true for all vertebrates, including humans, because all vocal muscles are developmentally related,” Adam says.

The team believe the findings might have applications in training and rehabilitation of vocal muscles in humans.

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