64. The Australian moth that migrates with the help of the stars…

Link to a YouTube interview with Eric Warrant

One of the most exciting trips I undertook while writing Incredible Journeys was to the Snowy Mountains in South East Australia. There I joined Professor Eric Warrant of the University of Lund and his colleagues who were seeking to show that the migratory bogong moth could use the Earth’s magnetic field to set a course during its long nocturnal migrations. They succeeded and I described their experiment in the book.

Bogong moth

Their latest research reveals that the mighty bogong can also make use of the stars!

They did this by flying the moths in a special simulator where the tethered insects were exposed to overhead patterns of stars that either matched those they would experience during their migrations or were randomised. They recorded the orientation of the moths under these different conditions and showed both that they could orient appropriately under the realistic ‘skies’ and that this ability disappeared under the randomised ‘sky’.

As if that weren’t enough, they also recorded the electrical activity in the navigational centres in the brains of the moths! They were able to identify previously undescribed neurons that respond to particular orientations of the night sky.

It’s long been known that some migratory birds have a stellar compass, and the Lund team had earlier shown that nocturnal dung beetles can make use of the Milky Way to set a course while rolling their dung balls over short distances. But the bogong moth flies hundreds or even thousands of kilometers!

Exactly what features of the night sky the bogong moths are attending to remains to be clarified, but it seems very likely that the ‘bright, extended stripe’ of the Milky Way (which is brighter in the southern hemisphere than the northern) plays a part in their navigation system too.

Watch this space…