In the name of science, researchers at the University of Wisconsin, Madison, decided to give some starlings the pleasure-inducing drug fentanyl to see what sort of songs they sung when in a good mood. The study, published in the journal Scientific Reports, revealed that after taking the opiate the birds began to sing “like free-form jazz”, a song style that they practice when singing on their own and which the researchers believe indicates they're feeling good.
To establish the mood-boosting powers of song, the study used a conditioned place preference test that is often employed in psychological research on animals to understand the reward of a behavior. They divided a test space using red and blue construction paper and placed the birds in one of the two colored chambers immediately after they had sung. The birds were then later faced with a choice between the two chambers and it was found that birds spent the most time in the colored chamber in which they were earlier placed after singing. The authors say this indicates the birds formed associations with the colored chamber and the beneficial effects of singing based on their past experiences.
Fentanyl is an opiate used in medicine that provides pain relief and is known to give patients a sense of euphoria. The researchers figured they could test if singing was associated with good feelings by inducing a good mood in the birds using the powerful opiate and observing how or if it altered their singing behavior. They gave a small dose of fentanyl to the birds and, sure enough, after the drug had been administered the birds began singing in a way that the researchers describe like free-form jazz.
Starlings sing a lot when they're in flocks, which the researchers believe is the result of the positive feeling brought on by being around other birds. They believe that gregarious singing when the birds are alone is an attempt to recreate the happiness brought on by flock-mates and that the reason why they sing when on fentanyl is because of the association of good feelings when singing. If a bird off drugs repeatedly performs a type of song when happy, it's possible that creating an artificial good mood with drugs could be the reason they jump into song when on fentanyl.
“It's evidence that a positive state is induced by the presence of flock-mates, which stimulates song, and that birds continue to produce gregarious song because it is rewarding,” said lead author and biologist Lauren Riters in a report from The Times. “Although male songbirds are famous for singing when they are away from other birds, for example when they are defending territories and attempting to attract mates, many birds also sing at high rates in more social contexts.
However, the team said they interpret their "findings cautiously because in this study the sample size for control birds was limited; however, the positive relationship between song and CPP observed in the controls here replicates results of four prior studies from our lab."
“Our results suggest that birds sing because they feel good, and that singing helps them to maintain this positive state,” said Riters in The Times.