UPSC Express

About Butterfy migration

• Usually butterfly migration starts during October-November with the onset of the northeast monsoon, from the plains to the ghats, and during April-May, just before the advent of the southwest monsoon, from the ghats to the plains.
• Migration takes place across the plains of southern India to the southern part of the Sahyadri (also known as the Western Ghats) between mid-October and early December every year.
• Migrant butterflies initially remain in reproductive diapause for a few weeks after reaching the Sahyadri.
• They then breed in these mountains, and their progeny migrates to the eastern plains between April and July the following year.
• Thus, butterflies leave the southern Sahyadri just before the onset of the south-western monsoon, and return soon after the monsoon rains subside, escaping the nearly incessant rains and mist that cover the southern part of Sahyadri from June to September.
• The butterflies breed during the south-western monsoon on the eastern plains, in the rainshadow area, and their progeny then migrate back to the Sahyadri between October and early December.

Way ahead

• Butterfly migration is one of the least studied natural phenomenon in the country.What is needed is a careful documentation of migration over a prolonged period from a given area.
• For this, a wide network and coordination among butterfly watchers from different localities are needed