Despite its name, Silent Valley National Park in Kerala is filled with the sounds of the rainforest. However, for centuries, it was uniquely distinguished by the absence of a familiar chorus: the piercing calls of cicadas. This remarkable lack of insect noise gave the valley its English name and became a central part of one of India’s most famous environmental battles. Yet, recent reports and scientific surveys suggest that this long-standing silence may be breaking, and cicadas may be making a cautious return.
A Striking Ecological Riddle
The absence of cicadas in Silent Valley has long puzzled scientists. While cicadas are a common and noisy presence in most tropical rainforests, they were consistently missing from this 90-square-kilometer stretch of the Western Ghats. Scientists theorized that this might be due to the valley’s unique bowl-shaped topography, perpetual mist, and perpetually moist soil, which could be unfavorable for the insects’ underground nymph stage. Others suggested a natural baseline for this particular ecosystem, while some posited that subtle climatic shifts centuries ago might have driven them away.
For environmentalists in the 1970s and 80s, the “silence” was a powerful metaphor used to oppose a proposed hydroelectric project. The campaign, which used the lion-tailed macaque as its mascot, successfully led to the cancellation of the dam and the declaration of the area as a national park in 1984.
The Return and Its Implications
Recent anecdotal reports and field surveys indicate a potential change. According to Arya S of the Travancore Institute for Bioscience Research, the gradual return of cicadas, though in small populations, could signify slow ecological changes and resilience in the habitat. Their presence is an important indicator of ecosystem health, as they play a key role in nutrient cycling and the food web.
However, K Sujana, a scientist with the Botanical Survey of India, offers a more cautious perspective. She believes the cicadas’ resurgence may be a telling sign of ecological upheaval. “Habitat modifications triggered by invasive plants… along with rising temperatures and erratic rainfall, appear to be fuelling this resurgence,” she said. The soundscape of Silent Valley, in her view, is now mirroring the unfolding story of climate change and biodiversity shifts across the Western Ghats.
Researchers like Marri, a field researcher in the Western Ghats, see the return of the cicadas as a “whisper from the forest.” It’s a reminder that ecosystems are fluid and constantly changing. The question for scientists now is whether this change is a sign of positive recovery or a symptom of larger environmental stress. Long-term, systematic monitoring is needed to understand the implications of this shift and ensure the fragile balance of Silent Valley is maintained.