Testosterone may Increase Male Songbirds Desire to Sing

For the male canary, the hormone testosterone plays an important part in changing his song behavior and creating the perfect pitch when it comes to both song quality and frequency.

According to researchers at the Johns Hopkins University, they found that by introducing testosterone in select areas of the male canary's brain, this could help better attract a female partner through the bird's voice. The study also found that through enhancing song activity based on testosterone via one brain area, they could change the size of a separate brain area that works to regulate song quality.

Senior study author Gregory F. Ball, vice dean for science and research infrastructure and professor in the Department of Psychological and Brain Sciences in the Zanvyl Krieger School of Arts and Sciences, found that when male canaries received testosterone to a specific region of their brain, their song frequency increased. However, the quality of the songs  did not change when compared to other birds who received the hormone throughout their entire brain.

To test how the hormone influences birdsong, researchers divided 20 canaries into two groups in order to receive a hormone implant.

One of the groups received the testosterone injection in a specific area of the brain known as the medical preoptic nucleus (POM), while the second group received the hormone throughout the entire brain. A third control group received no hormone at all.

Study findings showed that birds who received testosterone only in the POM sang at higher rates but could not produce the best quality that attracted females. However, those that received the hormone throughout the brain produced more high-quality sound that was more likely to attract a mate.

"Our data suggests that testosterone needs to act in different areas of the brain to regulate the specific components of this complex social phenomenon," said graduate student and lead author Beau Alward, via a press release. "It appears that, like in so many other species, testosterone in the POM can regulate an animal's motivation, in this case, the motivation to sing. However, singing and courting a female is more than just motivation. There is the quality of the song that is required to successfully attract a mate and then the process of attending to the female, or singing to her, when she is there which requires the coordination of multiple brain regions."

Researchers believe that these results may ultimately help determine how steroid use in humans affects sexual behavior, as well as how hormones can help to regulate the different commponents of speech in humans.

More information regarding the study can be found via the journal Proceedings of the National Academy of Sciences (PNAS).