Field Notices: Monarch miracle

It’s been over a month since I saw the last monarch butterflies lifting from the purple asters in my back yard, but that doesn’t stop my thoughts from drifting south with those miracles of nature.

I say “miracles” because those insects, each half the weight of a dollar bill but eight times as gorgeous, now hang in clusters from oyamel firs on a cool volcanic mountain slope in Mexico.

Most miraculous of all, when a monarch next flutters into my yard in June, that butterfly will be three generations removed from the ones that left nine months earlier.

I recently talked to Lee Zieke Lee, who has spent many August and September afternoons tagging Northeastern Iowa monarchs. She is part of a volunteer network that has helped map the migratory lives of monarchs east of the Rockies.

“Originally we glued on tags,” Lee said. “Later we sandwiched the tag around the edge of the wing. Now it’s a little sticker.”

Most insects, cold-blooded organisms with little way to keep warm, have evolved to overwinter in place, riding out the frigid months in an egg, pupa or larval form, in the earth, under water or wrapped in some secure envelope.

Not monarchs. Monarchs are the sole seasonally migrating butterfly. Those that hatch in August in Iowa or Minnesota grow a bit larger, store a bit more fat, cluster into flocks and eventually fly 40 to 50 miles south each day in a rusty cloud made up of millions of migrating butterflies.

Once those far-flying adults reach the handful of appropriate slopes in Mexico, they hang on their roosting trees, burning as little metabolic energy as possible, until spring begins to warm the mountain air.

Lee, who was a county conservation naturalist in the late ‘70s, operates Willowglen nursery and landscaping business with her husband, Lindsay. In 1995 they made a winter trip to the Mexican state of Michoacan to see where the monarchs they tagged wintered.

Lee marvels that the journey they made by plane, by car and finally by foot through the mountain air up to Santuario de la Mariposa Monarca El Rosario is repeated unerringly on the wing every year by migrating monarchs.

Lee said the roosts were “like spruce trees heavily laden with snow, except instead of snow you have butterflies.”

Lee and Lindsay Lee searched the slopes of El Rosario, hoping to find a male or female they had tagged in Iowa, but without any luck. Two weeks later, however, someone else found one.

“It’s a pretty neat feeling,” Lee said, “to find that a butterfly you banded in Winneshiek County ended up 1800 miles away in a town named El Rosario west of Mexico City.”

In spring, monarchs begin mating and fly north, the females laying eggs on the new spring milkweed plants they encounter, eventually dying on the journey.

The butterflies born from those eggs hatch with the impulse to fly north even further.

And so it is, that in late May or early June the great-grandchildren of last year’s migrating monarchs fly into Decorah where, instead of continuing north, their own offspring may very well stay for a generation or two. Unlike the long-lived overwintering insects that live eight months before reproducing and dying, early summer monarchs measure their lives in weeks.

To entice monarchs to add their color to our garden, I make sure to let a few milkweed plants, the favored food of monarch caterpillars, grow up between the cosmos and the roses.

If you want to be part of the volunteer force that annually helps monitor the geography of the orange-and-black-winged monarch miracle, go to www.monarchwatch.org.

There you can get access to the instructions, the equipment, the monitoring tags and the registration that could help you, as school is getting started next fall, press the record of its point of departure on a butterfly that will bring in the new year, 2010, in an orange fiesta of color on a fir branch in Mexico.