Female birds sing to find a faithful companion

Female songbirds sing more often than many once believed. A new study led by Professor Karan Odom uncovers why. Female song arises from a mix of climate, territory, and teamwork.

The researchers examined over 1,300 bird species. They discovered that female birds are more likely to sing in species that stay in one place year round, share parental duties, and defend territories together. These conditions occur most often in tropical regions.

This challenges the long-held idea that birdsong evolved mostly in males. Odom’s 2014 study already showed that female song existed early in avian evolution but was later lost in many lineages.

When and why female birds sing

The new analysis showed that year round territoriality and biparental care predict female song better than latitude alone. These traits often appear together in tropical species.

Species in which both sexes sing equally tend to have larger bodies and stable partnerships. When asked if busy moms stop singing, Professor Odom said “not exactly.”

“But separate parental and territorial roles do appear to lead to differences in male and female behavior. Some birds have the same mate all year or for multiple years, which leads to males and females acting more similar.”

“But if the birds are not monogamous, if the male breeds with multiple females, then we have observed that their traits diverge, and we find support that the male gets a really flashy, complex, long song, and the female gets a short song, or she loses her song.”

These differences arise as mating systems shift. When males breed with several females and skip parenting, female birds sing less or not at all. Singing near the nest may also attract predators, discouraging song.

Singing to find faithful partners

“They might just breed once and then go and find another mate, and then the female, in those cases, does all the work on her own: she’s raising the chicks and feeding the chicks, and that would be where you observe less female song,” said Professor Odom.

“This might be because when the female spends so much time around the nest, it is detrimental to sing.”

The study reveals that female song is not just about attraction. It is a strategy. Female birds may use song to secure a mate who will help raise offspring. The strongest female song appeared in monogamous species with cooperative males.

“I get excited about the parental care being significant because that’s not something people have tested before. That’s a new result, and it reaffirms that females could be competing for good mates or good dads,” said Professor Odom.

Some birds sing together and share duties

The study confirmed that duetting birds typically exhibit year round territoriality and equal parental roles.

Duetting species, often tropical, tend to have larger bodies and low levels of polygyny. This supports the idea that song helps maintain social bonds and territories rather than just attract mates.

The team found that 59 percent of songbird species include singing females. Among them, many have songs as frequent and complex as males. Others sing occasionally or only in certain contexts.

Female bird with hidden songs

The story does not end in the tropics. Even in temperate zones, some females sing. This occurs more often in species where males help raise young or where competition among females matters.

Species with moderate levels of polygyny and weak territoriality still show female song, though less frequently. This suggests song is not strictly for attraction. It might help females compete for resources or nesting support.

Traditionally, science underreported female birdsong. Observers often assumed males were the only singers. Many field guides and sound libraries underrepresent female voices.

“I truly love my work,” said Professor Odom. “I feel very passionate about it. It’s a field I’ve been in for about a decade now, and I self-selected it out of pure enthusiasm.”

“I went where the questions guided me and what I found most exciting, and then I spend a lot of time and energy on the research.”

The study is published in the journal Nature Communications.

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