Dragons Across the Ocean

Flecks of gold and red
shimmer over restless seas.
Incandescent gatherings
illuminating the horizon
as you throw yourself
to the mercies of the wind.
Your feeble frame
held aloft by crystalline wings,
as memories that are not your own
lead you to the water’s edge.
Skimming currents and zephyrs
you dance across the skies,
casting off for distant shores
you will never reach
alone.

This poem was inspired by recent research, which has found that dragonflies can migrate thousands of kilometres across the Indian Ocean, from India via the Maldives to Africa, and back again.

The globe skimmer dragonfly (Pantala flavescens) is considered to be the most widespread species of dragonfly on the planet and is found on every continent except Antarctica. It has long been known that these dragonflies make annual multigenerational journeys of thousands of kilometres. After being observed in the Maldives in 2009 it was hypothesised that these globe skimmers could potentially migrate more than 2,000 km across the open Indian Ocean, as part of a two-way migration between India and Africa. However, it was not entirely clear how an insect that is only 5 cm long and weighs just 300 mg would be able to do this.

In this new study, researchers show that relying only on self-powered flight (i.e. active flapping and gliding), a globe skimmer could theoretically cross the Indian Ocean, but the migration would have to occur where the ocean crossing is shortest, at an exceptionally fast gliding speed and with little headwind. As such, it is much more likely that wind assistance is essential for the crossing. By modelling the wind speeds across the Indian Ocean at different times of the year, the researchers were able to show that by making use of favourable wind conditions about 15% of the dragonflies could manage the migration from India to Africa in the spring, while in the autumn, 40% could make the same journey in the opposite direction. This is thought to be the longest migration in the animal kingdom in relation to an animal’s size, and further research is now needed to model these migratory patterns, and to also better understand the ways in which a changing climate may affect global wind patterns and thus such large-scale migrations.