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Monarch butterflies use a sophisticated navigation system to transverse 2,000 miles from breeding sites across the eastern United States to central Mexico, according to a new study. 

According to the study, monarchs use a light-dependent, inclination magnetic compass to help them orient southward during migration. 

"Taken as a whole, our study reveals another fascinating aspect of the monarch butterfly migratory behavior," said senior study author Steven Reppert, MD, the Higgins Family Professor of Neuroscience and distinguished professor of neurobiology at UMass Medical School in the press release. "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. A new vulnerability to now consider is the potential disruption of the magnetic compass in the monarchs by human-induced electromagnetic noise, which can also affect geomagnetic orientation in migratory birds."

The study reported that monarchs use a time-compensated sun compass in their antenna that helps them in making their 2,000 mile migratory journey to overwintering sites. When there is an absence of daylight cues, like under dense cloud, migrants were seen flying in the expected southerly direction. 

"Our study shows that monarchs use a sophisticated magnetic inclination compass system for navigation similar to that used by much larger-brained migratory vertebrates such as birds and sea turtles," explained co-author Robert Gegear, PhD, assistant professor of biology and biotechnology at WPI, in the press release. 

The identified component has been detailed in the journal Nature Communications.