The male nightingale’s elaborate song advertises to potential mates how good a father he will be, new research finds.
The quality of the “dad song,” which has inspired well-known composers such as Mozart, turns out to be directly linked to how devoted the bird singer will later be to his chicks, and how often he will feed them.
Pay particular attention to the evening singing recorded in the second half of this video, since it’s similar to what the researchers studied:
The study, published in the journal BMC Evolutionary Biology, further reports that multiple song features — complex whistling, trilling, buzzing and more — all seem to be important in communicating dad skills.
“It has long been thought that a single feature, the size of a bird’s song repertoire, may be important for females during mate choice,” lead author Conny Bartsch of Berlin’s Freie Universität said in a press release. “But our study shows that, in nightingales, it is a mix of specific song features that seem to be more important in determining their paternal efforts.”
Bartsch added, “These song features have never been described before in any other species, and include the sequential ordering of songs and the use of acoustic structures that are most probably challenging to produce.”
For the study, she and her colleagues analyzed 20 male nightingales. The researchers recorded the birds’ nocturnal singing early in the breeding season, carefully documenting the different components of the songs. They focused on evening singing because it is associated with mating among nightingales, given that the male birds tend to croon in the evening before pairing up with a female and mating soon thereafter.
After the bird pairs formed, the researchers studied video footage of the birds’ nests and data from electronic tags that they’d previously attached to the male birds. The tags recorded male visits to the nests, and determined the level of fatherly care that the males provided to their chicks.
Bartsch and her team found that male nightingales contribute substantially to chick feeding, at a level equal to that of females. This effort alone is extraordinary, since both mom and dad nightingales perform around 16 nest visits per hour, on average, to feed their chicks.
Dads whose nocturnal songs were especially complex (with many different types of buzzes, whistles and trills) and more ordered contributed the most to chick feeding and exhibited greater paternal effort overall, the researchers discovered.
Another interesting finding was that these super dads tended to be older male birds. This suggests that ordered singing could serve as an indicator of experience with the breeding grounds, and could mean further benefits for females who choose males with appealing, attractive songs.
Humans seem to have latched on to the bird’s technique, with tunes such as “A Nightingale Sang in Berkeley Square” used to set a romantic tone, particularly back in the day.