Blue Tiger Butterflies Migrate to Western Ghats Amid Northeast Monsoon
• Millions of butterflies, including Blue Tigers (Tirumala limniace), Dark Blue Tigers (Tirumala septentrionis), Common Crows (Euploea core), and Double-branded Crows (Euploea sylvester), are migrating from the Eastern Ghats to the Western Ghats during the onset of the Northeast monsoon in October
• This seasonal migration is driven by the availability of host plants in the forests of the Western Ghats and the heavy rains affecting Chennai and surrounding districts. The butterflies travel westward across the Tamil Nadu plains, pausing at forest patches to feed and reproduce. The return migration typically occurs in April or May, coinciding with pre-monsoon showers and preceding the Southwest monsoon.
Impact & Risks
The migration is a significant ecological event, but it poses risks to the butterflies due to road collisions. Hundreds of butterflies have been killed along routes in Tamil Nadu, particularly in districts like Coimbatore, Salem, and Tiruppur. Observers have reported counts ranging from 5 to 135 butterflies per minute in some areas, with high activity noted on 17 and 18 October 2026. The loss of butterflies due to road mortality could impact their population and the ecological balance in the region.
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