The pristine beach of Dhanushkodi at the southern-most tip of the Rameswaram island in the Indian peninsula has witnessed a rare phenomenon over the past few days.
Thousands of Crimson Rose butterflies swarmed all available flowering plants along the beach. It was their stopover for nectaring, before the butterflies undertook their ultimate flight towards Sri Lanka, which is around 25 km away from the tip of Dhanushkodi.
Crimson Rose, a large butterfly with a mix of black, white and crimson colours on its wings and body, is known for crossing the sea to migrate to Sri Lanka.
Experts say the recent migration from Dhanushkodi in large numbers is significant. Paulmathi Vinod and Vinod Sadasivan from The Nature and Butterfly Society (TNBS) and independent observer S. Chandrasekaran witnessed every stage of the phenomenon. According to them, one by one, the butterflies used the coastline like a predetermined path and continued their journey.
The most interesting and visually stunning aspect of the migration was that the butterflies made small pit stops on flowering plants on the beach to fuel their journey, they said.
Crimson Roses were spotted on Ipomea flowers and Half leaf flowers on the beach. The grandest gathering was on a Calotropis gigantea plant, which was the sole plant in the vicinity. Each butterfly spent about 30 seconds on nectaring and then continued its journey towards Sri Lanka.
“We could not stop to wonder the importance of this little fuel stop as this could mean the difference between a successful crossing or a fatal ocean tragedy. This gathering just shows the importance of native beach vegetation in the journey of a butterfly and the importance of protecting the beaches in their original pristine form,” said Paulmathi Vinod.
According to A. Pavendhan of TNBS, Crimson Rose, which belongs to the Swallowtails (Papilionidae) family, is known to migrate along the coast, inland and crosses the sea often.
“Crimson Roses crossing the sea from Rameswaram and their presence in the Sri Lanka have been reported earlier. The current observation is significant since the magnitude of migration was clearly observed and reported, including the food stop they undertook. The TNBS team also observed a similar phenomenon, but on a lower scale from the Kanniyakumari coastal lines too,” he said.
Another significant factor of the migration was that the fragile creatures chose to cross the sea from Dhanushkodi, which is one of the closest Indian beaches from Sri Lanka.
Biologist and researcher H. Byju said that he has observed Crimson Roses flying towards Sri Lanka from the mainland and the Gulf of Mannar islands from 2016. Certain other butterfly species found in Tamil Nadu are also known for their migration in response to the climate and food availability, he said.
Migration by Tigers and Crows from the sub-family Danainae of Nymphalidae are known to migrate just before the onset of the southwest and northeast monsoons from the Western Ghats to the Eastern Ghats and plains, and vice-versa. Butterfly species like Common Emigrant, Common Albatross and Lime Butterfly are also known to undertake migration on a large scale, said Mr. Pavendhan.
