As I get older I do less, but I notice and wonder more. When Kat and I worked in New Orleans we lived on the north side of Pontchartrain, crossing that lake once a week. We often rode a lovely bike trail known as the Tammany Trace following the lake’s northern coastline. One autumn day we saw Monarch butterflies, hundreds of them, flying not south, but west. They have learned to use man-made structures such as highways and bridges to make their trip safer. These west-bound butterflies were headed toward the 24 mile Causeway to cross that huge lake. Need to rest? Then light somewhere off the highway along the bridge. Need a nice updraft to help you soar? The heat of the concrete and the motion of southbound vehicles create an updraft and a mini-wind going in the perfect direction: south. North-bound humans rarely see Monarchs over the Causeway, but they’re everywhere on the south-bound span in October.
Monarchs migrate from Canada and New England to a sixty square mile wintering site in the mountains of Mexico. They’ve never been there before, nor have their parents, grandparents, and great-grandparents who all made their migrations going north. But somehow every fourth generation navigates the 3,000 mile flight. Science has narrowed their homing skills down to some combination of magnetic fields, stars in the night skies, and the angle of the sun. These butterflies hatch in August, became capable of flight in early September, and two months later find 100,000,000 cousins and a few siblings clustered in oak groves at 10,000 feet. The local people, the Mazahuas, have lived in those for mountains for hundreds of years. They view the butterflies as the spirits of their ancestors. The arrival of the Monarchs, typically en masse, triggers a celebration known as The Day of the Dead.
It takes four generations of Monarchs to complete the round trip. This fall’s southbound generation will winter in Mexico, then mate, lay eggs, and die in late spring. Their eggs become adult butterflies and migrate north to the Gulf States. One month later their life cycle is complete as they mate and die. The next generation survives but a single month after migrating to northern USA. The next generation also lasts one month, laying their eggs in Canada and far north New England. Next year’s magical fourth generation lasts nine months including their six week flight south and a long winter’s rest.
The Monarchs’ long-term prospects are not good. Various species of milkweed are their favored food, but modern agriculture and suburban civilization wage relentless war on all weeds. Illegal logging in Mexico is rapidly clearing away their winter habitat, and the biggest trees (which hold the most heat over cold nights) are the best for Monarchs. How many butterflies are needed for a successful migration is an open question.
Campbellsville is on the edge of their flyway south. I’ve seen several lately, some stopping to sip clover nectar and others to drink water after a rain. They are here today and gone tomorrow: a metaphor for human life. I cheer on those who come within earshot: “Be careful, brother. It’s still a long way to Mexico.”