The butterfly effect

If you happen to see a swarm of butterflies flying above the terrace of your office in the crowded Bengaluru city, count yourself lucky. You are witness to the largest annual butterfly migration in southern India. Every year between October and December, swarms of Dark Blue Tiger and Double Branded Brown Crow fly through the Bengaluru-Mysore area to their summer homes in the evergreen forests of Sahyadri in the Western Ghats. There they crowd in dense congregation for weeks, court and breed.