Warrant is Professor of Zoology and Head of the Lund Vision Group at the University of Lund in Sweden, Visiting Fellow at the Research School of Biology at the Australian National University and Adjunct Professor at the University of South Australia. Warrant leads an active research group studying vision and visual navigation in animals from extremely dim habitats (nocturnal and deep sea). Using electrophysiological, optical, histological, behavioral and theoretical approaches, Warrant studies how animals as diverse as nocturnal insects, deep-sea cephalopods and fast-swimming predatory fishes are able to see well at very low light levels, and his research has led to the discovery of neural principles that permit vision in dim light. In recent years Warrant’s group has turned its attention to the sensory basis of long-distance migration in nocturnal insects, particularly the role of the Earth’s magnetic field and the stars in migratory navigation. Warrant’s work is funded by an Advanced Grant from the European Research Council, as well as from the Swedish Research Council. Warrant is Past-President of the International Society of Neuroethology, Fellow of the Royal Danish Academy of Sciences and Letters, Fellow of the Royal Institute of Navigation and Fellow of the Royal Physiographic Society, and sits on the Senior Editorial Board of the Journal of Comparative Physiology A and also on the Academic Advisory Board of the Proceedings of the Royal Society B.

Australian Bogong moths use the stars and the Earth’s magnetic field as compasses for long-distance navigation at night

Each spring, billions of Bogong moths escape hot conditions in different regions of southeast Australia by migrating over 1000 km to a limited number of cool caves in the Australian Alps, historically used for aestivating over the summer. At the beginning of autumn the same individuals make a return migration to their breeding grounds to reproduce and die. By tethering spring and autumn migratory moths in a flight simulator, we discovered that Bogong moths are able to sense the Earth’s magnetic field and correlate its directional information with visual cues to steer migration. We also discovered that a critically important visual cue is the distribution of starlight within the austral night sky. Under natural dorsally-projected night skies, and in a nulled magnetic field (disabling the magnetic sense), moths fly in their seasonally appropriate migratory directions, turning in the opposite direction when the night sky is rotated 180°. Visual interneurons in the moth’s optic lobe and central brain respond vigorously to identical sky rotations. Migrating Bogong moths thus use the starry night sky as a true compass to distinguish geographic cardinal directions, the first invertebrate known to do so. These stellar cues are likely reinforced by the Earth’s magnetic field to create a robust compass mechanism for long-distance nocturnal navigation. 

Keywords: migration, navigation, stellar compass, Bogong moth, Agrotis infusa