The conductor of the chorus
In the dense rainforest of the Morowali Nature Reserve, sound is a physical presence. The air hums with a chorus of insects so loud it can be disorienting, with some accounts describing the sound of local cicadas as an intense, eerie siren. Most cicada choruses are the collective work of males, who use specialized, drum-like organs called tymbals to produce mating calls that can exceed 120 decibels, louder than a rock concert. The male abdomen is often mostly hollow, acting as a resonance chamber to amplify the sound. Females are typically silent participants, listening for the right species-specific call.
The acoustic behavior in Morowali, however, points to a deviation from this standard model. The chorus is said to begin only after a specific sound is produced by a single female, a matriarchal figure that seemingly directs thousands of males to begin their song. This form of female-initiated signaling is exceptionally rare in the cicada world. While females of some species produce quiet clicks or wing flicks to show interest in a courting male, they do not typically lead the performance. This unique acoustic trigger in the Morowali forest suggests a complex communication system that defies the common patterns of cicada behavior.
A hotspot of insect evolution
The island of Sulawesi is a hub for cicada diversity, making it a perfect location for unusual evolutionary traits to appear. The genus Dilobopyga alone contains 48 species, 43 of which are endemic to Sulawesi and its immediate surroundings. Many of these species are confined to very specific territories within the island, creating isolated populations where unique behaviors can develop. The extreme biodiversity forces species to evolve distinct communication strategies to avoid their signals being lost in the noise of a shared ecosystem. Some Southeast Asian cicadas accomplish this by singing only at specific times of day, occupying a narrow acoustic window at dawn or dusk.
While a female-led chorus is an anomaly, it is not without precedent. Research on the Chinese cicada Subpsaltria yangi has documented a complete role reversal where females produce songs and males are attracted to them. The existence of such systems shows cicada communication is more flexible than once thought. The specific species behind the Morowali phenomenon remains uncatalogued, potentially one of the many undiscovered organisms within the reserve's 200,000-hectare expanse. Further research here is important, but the region faces serious threats from deforestation and nickel mining, which endanger this unique acoustic habitat.