Daily vocal training necessary for mating males

Blackbirds and humans have largely similar musculature for singing.

ImageJohnér bildbyrå/Therese Ekström, Umeå University

"If song has the same social function among humans as birds, perhaps we should leave it unsaid... But the musculature to produce the song is largely common to all vertebrates, including birds and humans, so some of the results in the study are probably transferable to us," says Per Stål, professor at the Department of Medical and Translational Biology at Umeå University and one of the authors behind the study.

It has long been something of a mystery why songbirds spend so much time and energy per day singing, even when it seems unnecessary and they have no conspecifics within hearing distance. Now, an international research project has found the answer. It is the males who practice in order to be able to impress the females with their beautiful song and thus get the chance to mate.

The study showed that after a week's break from singing, the birds' vocal muscles had lost 50 percent of their ability. The researchers studied recordings of birds of the zebra finch species before and after their daily training sessions. The changes were clearly visible when studying the recordings in detail, even if a human ear could not hear them. However, the female birds are very picky listeners and can immediately tell if a male has been careless with the exercise, even if only for a single day. In trials, females consistently chose males who had not taken a break in vocal training.

The study is a collaboration between researchers at the University of Southern Denmark in Odense, the University of Leiden in the Netherlands, the University of Vermont, USA and Umeå University. The researchers in Umeå have mainly focused on studies of changes in the musculature behind singing.

Singing may seem simple, but it actually requires an incredibly complex interplay between a very large number of muscles. However, the vocal muscles of humans are surprisingly poorly explored; The larynxes of the great tenors are something of a trade secret. Therefore, it is interesting to be able to study great singers in the animal kingdom in order to develop clinical voice treatment methods.

Per Stål, Universitetslektor vid Institutionen för integrativ medicinsk biologi (IMB)

ImageMattias Pettersson

"What is remarkable is that the vocal muscles seem to react in opposition to other muscles in the body during exercise. We could see that the vocal muscles became faster as a result of exercise, instead of stronger and more enduring, which is how arm and leg muscles normally react when we train at the gym," says Per Stål.

opposition to other muscles

The researchers hope that the study will eventually contribute to an understanding of how to improve voice training and rehabilitation among people. Songbirds, or oscines, are a very large group of birds, which includes many of our most common species such as corvids, starlings, thrushes, sparrows and finches.

The study is published in the scientific journal Nature Communications.