Monarch butterflies use ‘sun compass’

Monarch butterflies use the Earth’s magnetic field and a ‘sun compass’ in their antenna as navigational tools for their long-distance migration, scientists say.

Monarchs use a time-compensated sun compass in their antenna to help them make their long-distance migratory journey to overwintering sites, researchers found.

Each year millions of monarch butterflies use a sophisticated navigation system to transverse 3,218 km from breeding sites across the eastern U.S. to an overwintering habitat in specific groves of fir trees in central Mexico.

Scientists at the University of Massachusetts Medical School and Worcester Polytechnic Institute found that monarchs use a light-dependent inclination magnetic compass to help them orient southward during migration.

During the absence of daylight cues, such as under dense cloud cover, migrants have been, surprisingly, seen flying in the expected southerly direction.