According to a recent report, Tamil Nadu witnessed large-scale migration of butterflies belonging to the Danainae sub-family from the Eastern Ghats and plains towards the Western Ghats during September.
- Butterflies of the Danainae sub-family, such as Blue Tiger, Dark Blue Tiger, Double-branded Crow, and Common Crow, are known to migrate from the Eastern Ghats and plains towards various nearest hill ranges of the Western Ghats before the start of northeast monsoon.
- During April and May, these butterflies, generally called ‘tigers and crows’ migrate from the Western Ghat hill ranges towards the Eastern Ghats and plains of Tamil Nadu, before the onset of the southwest monsoon.
- Their southwest movement, towards the arc of hills in the Western Ghats between the Anamalai Tiger Reserve and the Nilgiris, was tracked from the Sathyamangalam hills in Erode, Tiruppur and Coimbatore.
- According to a researcher, the large-scale movement could be attributed to good rainfall during the just-concluding southwest monsoon season.
