Blue tiger butterflies swarm Coimbatore, counts hit 120 per minute during monsoon migration

UPDATE - follow-up to Butterfly migration: Blue tigers head towards Western Ghats with the onset of North-East monsoon: Blue tiger butterflies are streaming through Coimbatore, with observers counting up to 120 individuals per minute as they migrate from the Eastern to the Western Ghats to escape the North-East monsoon.

What Happened

Observers in Coimbatore reported 100‑120 butterflies per minute on Oct 18, with a peak of 120 at 9:50 am on Kalapatty main road. The counts came from members of The Nature and Butterfly Society (TNBS) who monitor the migration via a WhatsApp group that alerts participants in Salem, Erode, Tiruppur, Coimbatore, Madurai and Kerala. Dr Kalesh Sadasivan of the Travancore Nature History Society explained that the insects travel to forest host plants, feed, mate and die after laying eggs, while later generations return in May.

Reaction

CV Nishanth, core TNBS member, described the flight as “blue and dark blue tigers, common and double‑banded crows, and a few emigrants” filling the sky. Pavendan, founder and president of TNBS, noted that on sunny days about 100 butterflies can be seen within a 50‑100 m stretch, amounting to roughly 6,000 crossing that distance in an hour. He added that butterflies rest on trees by 3 pm and resume flying the next morning, and that they serve as indicators of a healthy ecosystem and food for spiders and birds.

Context

The migration follows the pre‑monsoon showers in the Eastern Ghats and signals a seasonal shift that supports forest biodiversity in the Western Ghats.