Monarchs: Small creatures, big moves

The monarch rode the wind through the Eastman Nature Center in Dayton, sweeping down a bike path, then through fields of tall, tangled grass that bent with each gust. Finally, it alighted on a stem of goldenrod, oblivious to its stalkers: Three Rivers Park volunteer Emily Beltt and several curious children.

Using her net, Beltt caught the butterfly.

Seconds later, she gently held the female monarch in one hand and placed a small tracking sticker on its wing. The sticker, experts assure, would not weigh the monarch down or impede its flight.

This time each year, monarchs -- which weigh well under an ounce and are the only migrating butterfly in Minnesota -- begin their 1,800-mile annual journey to Mexico.

Along the way, many will die from storms, starvation, fatigue and predation, but the ones that make it represent an incredible natural phenomenon that University of Minnesota monarch lab scientists and others nationwide are still trying to fully understand.

The Nature Center's three-weekend program to tag the insects as they prepare for migration is one of numerous such programs in the Twin Cities -- the Minneapolis Monarch Festival is this weekend -- designed to help scientists do their field work. Armed with the standard stickers bought online, parents and intrigued naturalists can also tag monarchs at home.

Most monarchs do not migrate, and live only about two to four weeks as adults, laying eggs constantly until their death. However, migratory monarchs can live up to seven months, a necessity in completing the long trip that takes them south to Mexico for the winter. Then in early spring, they fly to Texas, where they lay eggs and die. It is those offspring that return to the northern states to continue the cycle.

Monarch specialists believe that migrating butterflies do not reproduce until they leave Mexico for Texas in the spring, thus expending much less energy than their short-lived kin.

If there are cooler temperatures during their stay in Mexico, that may also slow down their metabolism and increase their longevity, according to Karen Oberhauser, a researcher at the University of Minnesota's monarch lab.

It's the tagging system, done in prairies throughout North America, that has allowed researchers to make educated assumptions about monarch migration and that could yield answers to some of the questions that remain.

"Tagging records give us the potential to learn how monarch production varies from year to year, location to location, and what weather factors influence their numbers," Oberhauser said. "Combining tagging data with data from other monitoring programs can give us a stage-by-stage picture of monarch numbers as they breed, migrate and winter in Mexico."

The beginning

Currently, there is no comprehensive system that keeps track of all tagged monarchs to determine what percentage survives from each region and calculates death rates.

In addition, the recovery process is slow and far from complete, relying largely on locals as well as research staffs to report found (and most often dead) monarchs.

While Oberhauser thinks there is room for improvement, "all that will come," she said. "It has incredible potential to help us understand and conserve monarchs."

Sending them off

Wachtler heads the monarch tagging program at Eastman Nature Center, which invites the public three Sundays each fall to learn about the species and participate. The first step in tagging a monarch, she said, is to walk out to the prairie. "That's our best chance to catch one, when they've landed on a flower, and they're eating."

Each year, Eastman typically tags and releases about 75 monarchs, many of which have been raised in-house. This year, that number will be slightly stunted because a disease infected some of the eggs. But the second week of tag and release turned out to be a peak time for monarch catchers, Wachtler said; the small band caught six, despite the day's high winds.

"You'll see them at night, as they come from up north," she said. "Hundreds of them will come to the evergreens and roost at night. Usually, they take off the next day."

From Minnesota, they have a long way to go. "The entire journey [to Mexico] usually takes about two to three months, if they are lucky," Wachtler said.

"There it goes," Beltts said, watching as her monarch took off, with a tiny sticker attached, dancing against the flat, blue-skied horizon until it disappeared somewhere behind the pines, perhaps headed south. To Mexico.

Amelia Rayno • 612-673-4115