Flyer Miles - Naturalist Notes

Flyer Miles

Every year thousands of Michiganders fly to the arid mountains in the Mexican state of Michoacán, 10,000 feet above sea level and far from large cities. They join millions of others from nearly every other US state and stay from October until March every year.

In Mexico, the monarchs cluster in trees overnight, huddling together for warmth and forming dense, dark clusters. As the sun hits them and warms the earth, they move down from the mountains and fly, getting warm and feeding on flower nectar.

The annual migration of the monarch butterfly is one of the longest undertaken by an insect in the world, with some individuals traveling 3000 miles. Interestingly, the monarchs undergo this incredible journey not to breed, but simply to survive the winter. Unlike other moth and butterfly species, the monarch pupae cannot survive below-freezing winter temperatures. The monarchs don't breed and lay eggs until the spring when they begin the journey back north.

No one butterfly will make the round trip. While the journey down to escape the cold is undertaken individually, the journey north is done by successive generations, sometimes taking 3 generations to get back to Michigan. This explains why we don't see monarchs until later in the summer, long after the other insects have emerged. You can track and even report the annual migration at journeynorth.org. It's an incredible trip and requires that butterflies who have never been return to a relatively small region in Mexico every year. To get to the same spot I needed 2 three hour flights, a three hour car trip, a 30 minute horse ride and a 15 minute hike up some steep trails!

Submitted by Will Jaquinde, Operations Specialist, January 2022