As dusk falls over some swamps and ponds, the air fills with frog calls — sharp, steady, and almost always from males. For decades, scientists have focused on these loud, attention-grabbing sounds. But a new study suggests they’ve missed half the conversation. Particularly, the female half.
Published in Proceedings of the Royal Society B, the review finds that female frog calls have been recorded in just 1.4% of species. That means nearly all we know about frog communication comes from the males.
The researchers say this gap has shaped how we understand mating, behavior, and even the evolution of frogs — and it’s time to listen more closely.
Not Just a Gentleman’s Club
For decades, bioacoustics research has been dominated by males — male birdsong, male primate calls, and male frogs’ choruses. That bias was never more evident than in anurans, the group of amphibians that includes frogs and toads.
Males are easy to hear. They sing loudly to attract females, assert territory, and outcompete rivals. But female frogs? Their calls tend to be softer, shorter, and in many cases, they simply get overlooked. But that doesn’t mean they aren’t calling.
The team noted that female calls have been neglected because they are softer and quieter than their male equivalents. These subtler sounds often drown in the chorus of males or are filtered out entirely by human ears and rudimentary recording equipment.
But this review, the most comprehensive of its kind, pieced together data from over 2,900 documents and zeroed in on 112 species across 53 genera. What emerged was a new map of frog communication — one where females are no longer mute.
A Richer Repertoire
Female frog calls are also quite diverse. Researchers classified them into six distinct types: advertisement, courtship, amplexus (mating embrace), release (to signal non-receptiveness), distress, and aggressive calls.
<!– Tag ID: zmescience_300x250_InContent_3
–>
The most common? Distress calls — emitted when captured or threatened. Courtship and release calls were also frequently reported. In one species, the smooth guardian frog of Borneo (Limnonectes palavanensis), females call more frequently than males and even form chorus-like aggregations around calling males.
Perhaps most surprising is the existence of female advertisement calls — signals meant to attract mates. These were long believed to be a male-only trait.
In the American bullfrog (Aquarana catesbeiana), females produce calls similar in tone and structure to the booming male “jug-a-rum.” In another case, the concave-eared torrent frog (Odorrana tormota) emits female vocalizations that are not only frequent and loud, but stretch into ultrasonic ranges — well beyond what the human ear can detect.
Female calls are not inherently simple, however. In some species, females have larger larynxes than males and produce vocalizations that are more elaborate and complex.
Why Does This Matter?
Understanding the full spectrum of frog vocalizations has real implications for science and conservation.
Frog calls are crucial for species recognition, mate choice, and territory disputes. These behaviors shape reproduction — and survival. In habitats where males vastly outnumber females, understanding how the quieter sex communicates could help conservationists rebalance populations or identify declining species before it’s too late.
It also reshapes ideas about sexual selection. The old paradigm painted males as performers and females as silent choosers. But if females are also calling — sometimes to attract mates, sometimes to compete — then perhaps mate choice goes both ways.
One-third of female vocalizations are linked to mate acquisition processes, the authors noted. This challenges the common perception of females as ‘silent choosers,’ emphasizing their potential competitivity.
Can You Hear Me Now?
If researchers want to listen more closely to female frog calls from now on, it won’t be all that easy.
Part of the problem is technological. Many of the field methods used to record frog calls are tuned for louder, more frequent signals — typically male. The authors urge future fieldwork to take the quieter side of the spectrum seriously. That includes improving recording sensitivity, using directional microphones, and incorporating audio analysis tools capable of distinguishing faint or high-frequency sounds.
It also means changing the way science labels its data. Female calls are often buried in the main text of papers, undocumented in audio databases, or lumped under “male” by default.
To help fix that, the researchers propose a new standardized classification system. “We hope this review motivates researchers to consider female frogs in future behavioural, ecological and evolutionary studies,” they write.
This review joins a growing movement in animal communication research that’s calling for a more balanced look at both sexes. Similar revisions have upended assumptions in birdsong, where female song is now known to be ancestral and widespread. Mammals, reptiles, and even insects are getting similar re-evaluations.
The absence of evidence is not evidence of absence, and in the case of frog calls, that absence has been overlooked for over a century.
For now, scientists are left tuning their ears — and their expectations.
