Citizen Science Salon is a partnership between Discover and SciStarter.org.
Every fall, declining day length triggers one of the most incredible phenomena found in nature: the annual fall migration of monarch butterflies. Across North America, monarchs undertake an epic journey — up to 3,000 miles — to reach their overwintering grounds in Mexico and the California coast. For the eastern population of monarchs, the migratory generation are the great-great-grandchildren of the monarchs that left Mexico the prior spring.
Their numbers peak during fall migration — at no other time of year is the population larger. Instinct pushes them on as they battle weather, hunger, fatigue and human-made obstacles to reach destinations they’ve never been to before. Yet somehow, they know the way.
