Death’s head hawkmoths use sophisticated navigation strategies for long-distance migration

Tiny trackers show that nocturnally migrating hawkmoths continually adjust their flight headings in response to winds and other topographical features to keep their course, researchers report, indicating that the animals use a sophisticated internal map and/or compass mechanisms for navigation during their voyages. The findings reveal new insights into how insects traverse such long distances during seasonal migrations and show that complex migratory strategies are not limited to vertebrates. Each year, trillions of migrating insects like butterflies, locusts, and moths, navigate vast distances across the globe on journeys that span continents, mountain ranges, seas, and a wide range of environmental conditions. Although long-range seasonal migrations are relatively well understood at the population level, how individual insects achieve them remains poorly understood. This is particularly true for nocturnally migrating lepidopterans, like the death’s head hawkmoth, which travels as much as 4,000 kilometers between Europe and sub-Saharan Africa. Given the challenges of tracking such small, night-flying animals over such long distances, individual moths have never been observed throughout their migration. As such, the capabilities and behaviors these creatures use to maintain straight flight paths over long distances are unknown. Myles Menz and colleagues attached tiny, very high frequency (VHF) radio transmitters to the backs of hawkmoths and tracked them via airplane throughout their nightly migration flights, obtaining detailed tracks for seven moths. Menz et al. discovered that the moths did not just fly in a direction with favorable tailwinds; they were also able to correct their specific flight headings – even in the face of disruptive winds and terrain features – to maintain straight flight paths toward their intended destinations. According to the authors, maintaining a consistently straight flight trajectory and flight speed throughout the night under variable wind conditions strongly suggests that the moth has an internal compass mechanism. This, alongside the insect’s exceptional night vision, indicates that the hawkmoth likely uses a combination of visual landmarks and Earth’s magnetic field to navigate considerable distances during migration.

For reporters interested in trends, a May 2021 Science study revealing the heights great reed warblers reach during daytime flights over geographic barriers reported a previously unrecognized behavior in migratory birds and might help to explain the evolution of nocturnal migration.