“American Idol” wannabes take note: Singing a sexy song could increase your chance of reproductive success─if you’re a canary.
A new study, published in this month’s issue of Ethology, suggests that canary mothers are more devoted to their young when they hear a sexy male serenade prior to reproduction.
“Females are able to allocate different investment in their young according to the attractiveness of the mate,” said Stefan Leitner, a postdoctoral biologist at the Royal Holloway, University of London and the lead author of the study.
Male canaries sing complex songs consisting of a distinct pattern of phrases, each containing a two-note “syllable” repeated over and over. These songs stimulate female canaries to build nests, begin pre-mating rituals and lay eggs.
But not all songs are created equal.
Researchers discovered that certain phrases in a canary’s song are “sexier” than other syllables, and can elicit more mating displays, in which the female bird crouches and flaps her wings. The songs generally judged to be sexy involve syllables that are complex—typically faster and covering a wider range of frequencies than less stimulating syllables.
“In canaries, the amazing thing is that some syllables in the song repertoire are known to be more attractive to females,” Leitner said. “The remarkable finding is that the female can alter physiology according to an acoustic stimulus.”
Leitner and his colleagues found that sexier songs don’t just influence a female’s outward behavior—they also affect reproduction. When the researchers played female canaries a recording of males singing sexy syllables, the females laid significantly larger eggs than birds that heard recordings of normal songs.
“It may be that this is a difficult kind of vocal gymnastics to achieve; it may be that males who do this are in very good condition,” said Roderick Suthers, a biologist at Indiana University who studies avian song production. “Maybe the female canaries pay attention to this particular kind of syllable because it tells them something about male quality—if these syllables are more difficult to produce, only the most competent males could produce them.”
A number of studies have shown that female birds invest more in eggs and offspring of males they perceive to be especially attractive. Such males often have genes that are more evolutionarily fit, and females are more likely to invest in making sure that the offspring of those males survive. This gives male canaries that croon sexy tunes better odds of passing their genes down to subsequent generations.
“Larger eggs,” Leitner said, “could mean that they could put more resources and more energy into these eggs, and the offspring hatch with a greater weight or are healthier.”
