More than just a sound of the season, the study pointed towards cicadas as important indicators of forest health and climate changes in the Eastern Himalayas
SHILLONG, May 25: Every year, as the skies open rain lashes the hills of Meghalaya, a familiar sound fills the forests which is the rhythmic chorus of cicadas as pointed out now by a new scientific study which has uncovered just how closely these forest songsters time their calls and movements to the monsoon’s changing moods.
Carried out over three years (2021–2023) in Ri-Bhoi district, the research was led by Graham Bakynson Ranee, a PhD scholar from North-Eastern Hill University (NEHU), under the supervision of Prof SR Hajong, in collaboration with Dr PW Shangpliang of St. Edmund’s College, Shillong. The team studied the behaviour, diversity, and habitat choices of five cicada species, all within the forested areas around the Botanical Survey of India’s experimental garden in Umiam.
The findings show that cicadas are sensitive indicators of seasonal change. The research revealed that July was the peak month for cicada diversity, coinciding with warmer temperatures (28.8°C to 29.5°C) and high rainfall (up to 567 mm in 2023). However, too much rain, above 150 mm in a short span, actually caused fewer species to emerge, suggesting that while cicadas rely on the rains, excess rainfall can silence their songs.
Among the five species studied, Pomponia linearis was the most abundant, commonly seen on forest edges and tall trees in areas with some human presence. This species, along with Cryptotympana corvus, played a key role in maintaining ecosystem balance. In contrast, rarer species like Scieroptera splendidula were seen as possible indicators of unique microhabitats.
“These insects are deeply tuned to the timing and strength of the rains,” the researcher noted. “Their lives and songs reflect how ecosystems breathe with the seasons.”
The study also observed that different cicada species have different calling times, some preferred twilight, while others sang during the morning or day. Males often called in groups, creating a synchronised chorus that carried their songs deeper into the forest to attract females.
The researchers found that cicadas preferred tall trees like Pterospermum, Dysoxylum, and Tectona, likely because of their strong vascular systems, which provide the sap these insects feed on.
More than just a sound of the season, the study pointed towards cicadas as important indicators of forest health and climate changes in the Eastern Himalayas. As climate patterns become more unpredictable, listening to cicadas might just help us understand how nature is adapting or struggling to keep up.