Guided by a “sixth sense”: unravelling magnetic migration in Monarch butterflies

Each fall, millions of Monarch butterflies take off from to migrate over up to 5.000 km to their overwintering sites. During their long journey, they employ a wide range of cues to maintain their southerly flight direction.

While monarch butterflies have been shown to be sensitive to magnetic information, its role during migration remains elusive. In this project, I will test the role of the Earth’s magnetic field during migration.

Using a double-wrapped 3D-Helmoltz coil, I will study whether butterflies can use magnetic cues as a compass to keep their migratory direction (Magnetic Compass).

In addition, by virtually displacing migratory Monarch butterflies, I will investigate whether they can also determine a specific goal location or even their own global position based on magnetic cues (Magnetic Map).I will next study the neural coding of magnetic information in the Monarch brain.

I will target candidate compass neurons within the navigation network of the central complex using multichannel tetrode recordings. I specifically aim to obtain recordings from the head-direction neurons during magnetic field manipulation. I will test how the different magnetic field components are encoded in central complex neurons.

In this way, I aim to obtain a detailed picture of the neuronal correlate for magnetic orientation.Besides compass or map, magnetic cues could also be used for compass calibration. While time compensation is a crucial aspect of a navigation, how it is established at a neuronal level remains elusive.

I will investigate the role of the magnetic field as a geo-stable reference system for compass calibration. To do so, I will combine magnetic manipulations and a simulated sun stimulus to create cue-conflicts.

I will use extracellular tetrode recordings in tethered navigating butterflies, to investigate the influence of cue-conflicts on the neural coding. I aim to unravel how magnetic and celestial cues are integrated to create a time-compensated sun compass.