In 2023, Tamil Nadu witnessed a remarkable natural spectacle as a massive migration of butterflies from the Danainae sub-family—known as the ‘tigers and crows’—took flight from the Eastern Ghats toward the Western Ghats. This year’s migration was notably larger than that of previous years, drawing the attention of ecologists and nature enthusiasts alike.
The Danainae Sub-family
The Danainae sub-family is known for its vibrant and resilient species of butterflies, including:
- Blue Tiger
- Dark Blue Tiger
- Double-branded Crow
- Common Crow
These butterflies follow a unique two-part migration pattern. The first leg of their journey takes them from the plains to the hill regions before the onset of the northeast monsoon, which brings heavy rains to the region. Following the southwest monsoon, these butterflies return to the plains, completing the second phase of their migration cycle.
Tracking the Migration Pattern
The Nature and Butterfly Society (TNBS) has been monitoring this annual migration since 2013. Typically, the butterflies begin to emerge in late September, with large swarms seen moving across the landscape from morning until evening. On peak days, hundreds of butterflies can be seen migrating through designated areas, creating a mesmerizing display.
The migration reached its zenith on September 28, 2023, when massive groups of butterflies were spotted in regions such as Yercaud, Salem, Tiruppur, and Coimbatore. In some locations, observers recorded an astounding sight, with 10 to 200 butterflies passing by every minute, painting the skies with color.
Key Factors Behind the 2023 Migration
The large-scale migration in 2023 can be attributed to favorable weather conditions during the southwest monsoon. Abundant rainfall provided ideal breeding conditions for the butterflies, allowing their populations to flourish and resulting in a more significant migration. In contrast, the previous year’s migration was relatively subdued due to insufficient rainfall, which hindered butterfly reproduction and migration.
Mapped Areas of Migration
Several key areas were marked for their high butterfly activity during the migration, including:
- The Sathyamangalam and Dimbam hill ranges
- Districts like Coimbatore, Madurai, and the Nilgiris
In these regions, large numbers of butterflies were spotted moving in their characteristic migratory swarms, creating a striking spectacle for onlookers and naturalists.
Diversity Beyond ‘Tigers and Crows’
While the Danainae sub-family butterflies are the stars of this migration, other species also took part in this mass movement, enriching the diversity of the event. Notable among these were:
- Lemon Pansy
- Tawny Coster
- Common Emigrant
- Chocolate Pansy
The presence of these species highlights the ecological richness of the migration and underscores the significance of these butterflies to the biodiversity of the Western Ghats region.
A Natural Wonder Worth Preserving
This annual butterfly migration in Tamil Nadu’s Western Ghats serves as a reminder of the delicate balance between nature and the environment. The robust migration in 2023 was a direct result of favorable environmental conditions, reinforcing the importance of maintaining healthy ecosystems to support these remarkable creatures. As climate change and habitat loss threaten butterfly populations worldwide, the migration offers a glimpse of nature’s resilience and the beauty that thrives when conditions are right.
Efforts by organizations like TNBS to monitor and document these migrations provide invaluable insights into the behavior and health of butterfly populations. Preserving these delicate migrations for future generations requires continued attention to environmental conservation and sustainable practices that support biodiversity.
In conclusion, the 2023 butterfly migration from the Eastern Ghats to the Western Ghats not only showcases the incredible resilience and beauty of these species but also emphasizes the need for ongoing conservation efforts to protect this natural phenomenon.