Male song sparrows (Melospiza-Melody) Sing with eventual variety, repeating each song type in a consecutive series called a “fight.” ONE new study, published in the journal Proceedings of the Royal Society B, shows that they follow a “cycle rule” when switching between song types, going through their repertoire in nearly the minimum number of rounds possible.
Song sparrows are a common passerine bird throughout North America, but only males sing. They use their song to defend their territory and court mates.
When courting, they belt out up to 12 different two-second songs, a repertoire that can take almost 30 minutes to get through as they repeat the same song multiple times before moving on to the next track.
Besides varying the number of repeats, men also shuffle the order of their tunes each time they sing their discography.
A big unknown, however, was whether men accidentally or intentionally change their song order and repeats.
To get some data on whether or not the birds intentionally mix and match their tunes, a team of ornithologists from Duke University and the University of Miami loaded up recording equipment, traveled to the backwoods of northwestern Pennsylvania, and set up microphones that trees pointed to it and patiently waited five hours a day.
After recording the entire suite of songs by more than 30 people, they pored over visual spectrograms of the trills and analyzed how often and in what order each song was sung.
The first clue that men were keeping tabs on their tweets to avoid repeats was that men generally sing through their entire repertoire before repeating a song, much like a Spotify playlist.
The researchers also found that the more times a sparrow sang a particular song, the longer it took it to return to that song, possibly to build hype and novelty once that song was played again.
For example, if a man sang song A 10 times in a row, he sang even more renditions of his other songs before returning to song A again. Alternatively, if song A was warbled only three times during a movement, a male song sparrow might recite a shorter rendition of the rest of his repertoire to return to the still new and underperformed song A.
Taken together, these results indicate that song sparrows possess an extremely rare talent with an equally unusual name: long-distance dependencies.
This means that what a male song sparrow is singing right now depends on what he was singing 30 minutes ago. That’s 360 times the storage capacity of the previous record holder, the canary, which can only juggle about five seconds of song information this way.
The human implications of this work, while impressive, are less clear. It suggests that the order of words in human language, which is similarly influenced by long-distance dependencies, may not be as unique as once thought.
It remains to be seen whether better blending ability will give men an edge in their love search.
Perhaps females retain interest in a mate who confuses them more and are less likely to sneak off with another male.
As with daytime talk shows, paternity tests are a good predictor of monogamy in birds, so counting how many chicks are fathered by a female’s nestmate compared to another bird in the neighborhood could be a future project for the team.
“Right now it’s only speculation whether these shuffling song sparrows will give Spotify a fight for their money to keep a woman interested, but they highlight our similar approach to the gym,” Duke University said Professor Stefan Nowicki.
“You have your running playlist and the reason for that is because running is kind of boring.”
“You know these 10 songs will motivate you, but if you want to run 20 songs, why not mix it up so next time you don’t hear the same songs in the same order?”
William A. Searcy et al. 2022. Long-distance dependencies in bird song syntax. Proz. R. Soc. B 289 (1967): 20212473; doi: 10.1098 / rspb.2021.2473