Mini-Breaths and Vocal Fry: How the Tokay Sings Longer

There is a particular ingenuity in the way evolution solves problems—not with grand redesigns, but with small adjustments, borrowed mechanisms, and the repurposing of what already exists. For the male tokay gecko, a nocturnal reptile known for its loud, distinctive mating call, the problem is simple: how to call longer without running out of air. The solution, according to a new study published in Proceedings of the Royal Society B, is a trick previously thought to belong only to songbirds—a tiny breath taken in the middle of a call, allowing the gecko to keep singing when its lungs would otherwise be empty .

The tokay gecko's advertisement call is a familiar sound across Southeast Asia, a two-note vocalization that sounds like "gecko" and carries through the night. Males produce these calls to attract mates and defend territory. But like all vocalizations, they require air. Most animals produce sound only during exhalation, and the tokay is no exception. This creates a constraint: the length of a call is limited by how much air the gecko can hold. For a male trying to impress a mate, a longer call is a better call—it signals greater respiratory capacity, which in turn suggests better health and fitness .

The study, led by researchers at the University of Southern Denmark, used acoustic analysis and deep-learning-based pose estimation to track the geckos' breathing during spontaneous calling . The results revealed two mechanisms that allow tokays to extend their calls beyond what their lungs would normally permit. The first is a "mini-breath"—a brief inhalation that occurs in the middle of the two-note call, between the "ge" and the "ko." This inspiratory vocalization is a feature previously documented only in songbirds, and its presence in a reptile is unexpected . The second mechanism is what the researchers call a "vocal fry register," a low-frequency, pulse-like mode of sound production that is more air-efficient than normal phonation. By switching to this register for the terminal portion of the call, the gecko can add more pulses without using more air .

Together, these adaptations allow the male tokay to produce longer, more elaborate calls—calls that function, as the researchers put it, as "honest signals of respiratory capacity" . A male with greater lung capacity can sustain a longer call, and that length becomes a reliable indicator of his physical condition. In environments with background noise, where males need to call louder and longer to be heard, this capacity becomes even more important. The study notes that anthropogenic noise may strengthen sexual selection on respiratory performance, favoring males who can compensate for acoustic masking .

The research also uncovered a third surprise: the geckos close their ear openings during vocalization. The closure is slow—about 0.47 seconds—which means it is not a reflex, but a precisely coordinated action timed with the call . This likely protects the auditory system from the gecko's own loud sounds, a function similar to the stapedius reflex in mammals, but achieved through a different mechanism. Unlike the reflexive ear protection found in birds and mammals, the tokay's ear closure appears to be integrated with its vocal-respiratory system, suggesting a unique evolutionary solution to the problem of hearing while making noise .

For the tokay gecko, the mating call is more than a sound. It is a performance, a display of stamina and health, and a signal that the singer is worth a mate's attention. The mini-breath, the vocal fry, the closing ears—each is a small adaptation, easily overlooked, that together allow the gecko to sing longer and louder than its lungs would otherwise allow. Evolution, it seems, is a master of making the most of what is available.

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Sources: Proceedings of the Royal Society B, Figshare, JoVE