Butterfly Migration Thrives In Tamil Nadu’s Western Ghats

October 5, 2024

Tamil Nadu recently saw a massive migration of butterflies from the Danainae sub-family, specifically the species called ‘tigers and crows.’ These butterflies moved from the Eastern Ghats (a mountain range in India) toward the Western Ghats. This migration in 2023 was much larger than in the previous year.

Butterfly Sub-family

The Danainae sub-family includes well-known butterflies like:

Blue Tiger
Dark Blue Tiger
Double-branded Crow
Common Crow

These butterflies typically follow a two-part migration pattern. First, they fly toward the hills before the northeast monsoon (which brings rain), and then they return to the plains after the southwest monsoon (another rainy season).

Migration Pattern

The Nature and Butterfly Society (TNBS) has been tracking this butterfly migration since 2013. Every year, they see a large number of butterflies emerging in the last week of September. The butterflies usually start migrating early in the morning and continue until the evening. On peak days, hundreds of butterflies can be seen flying across specific areas.

Key Observations

The migration reached its peak on September 28, 2023, when large groups of butterflies were spotted moving through various regions like Yercaud, Salem, Tiruppur, and Coimbatore. Observers recorded seeing between 10 to 200 butterflies per minute in some areas.

The large-scale migration in 2023 was linked to better rainfall during the southwest monsoon. This created good breeding conditions for the butterflies, allowing their populations to thrive. In contrast, the previous year saw less rainfall, which restricted the migration.