A recent study reveals that monarch butterflies (Danaus plexippus) have someting even better than radar and use their own magnetic compass when migrating.
Scientists have long believed that monarch butterflies only used the sun to navigate their way. However, a recent study published in Nature Communication suggests that monarch butterflies can navigate using their own magnetic compass, even on cloudy days when the sun is clearly visible.
It is normal for many types of animals to go on long distance migrations. Some of these migratory organisms like sea turtles and birds use internal magnetic compass to navigate over large distances. However, scientists have been debating if monarch butterflies have the same ability.
A new study led by Steven Reppert, a neurobiologist and professor of at University of Massachusetts Medical School, suggests that they have convincing evidence to show the migration pattern of monarch butterflies are not totally dependent on the sun to fly towards the equator in autumn. Reppert says that even monarch butterflies use a magnetic compass to navigate.
Reppert and his team put monarch butterflies in a flight simulator and changed the light levels and the magnetic field. The findings suggest that the monarch butterflies used changes in the magnetic field to position themselves, rather than just trusting the location of the South Pole or the North Pole.
"Our study reveals another fascinating aspect of monarch butterfly migratory behavior. Greater knowledge of the mechanisms underlying the fall migration may well aid in its preservation, currently threatened by climate change and by the continuing loss of milkweed and overwintering habitats," per the study.
Reppert says that even though the monarch butterflies use the sun compass to migrate, they also use the magnetic compass as a backup.
The scientists are still unaware as to how animals sense magnetic fields. The researchers believe that certain molecules in the butterfly's body can sense the Earth's magnetic field and transmit the information to the brain.
"Another vulnerability to now consider is the potential disruption of the magnetic compass in monarchs by human-induced electromagnetic noise, which can apparently disrupt geomagnetic orientation in a migratory bird," says the study.
Reppert believes that more research is now needed to establish whether monarch butterflies are susceptible to electromagnetic interference.
Karen Oberhauser, a monarch butterfly expert and University of Minnesota professor, says that the latest study may attract more researchers who can hopefullyt try to understand the migratory abilities of monarch butterflies.
