Ever tagged a butterfly? Volunteers are marking monarchs to track their migration
Updated October 18, 2023 at 6:56 AM ET
With a flutter and flap of wings, monarch butterflies soar through the air and float from flower to flower at the DeSoto National Wildlife Refuge in Iowa.
Everyone in the Ivey-Caldwell family gives chase — scampering through the wilderness, popping over tall wildflowers with nets in hand on a warm Saturday.
"He's going to land way up high," says Laurie Ivey-Caldwell. She keeps close watch along with her husband, Julian, and their two sons, 11-year-old Eli and 10-year-old Ervin.
"I really love butterflies. I have loved them since I was little, and I love catching them," Ervin says.
Monarchs in the Midwest migrate to central Mexico
Throughout the late summer and early fall volunteers, like the Ivey-Caldwell family, come to the refuge to carefully catch and mark each monarch with a tiny sticker before letting them go.
Park Ranger Peter Rae oversees the sessions and says the goal is to tag 300 butterflies this season for researchers to try and follow their path.
"And they're not flying with another butterfly that has done it before," Rae says. "It's an amazing migration."
Typically, the monarchs live for only two to six weeks. It's the fourth or fifth generation of the season, known as the "super generation," that makes the migration. Those butterflies live for about nine months. They travel hundreds or even thousands of miles to reach their destination in central Mexico by early November. They return to their northern breeding grounds in early spring.
Helping to solve scientific mysteries
"There is something about a monarch that seems to capture the feelings of people. It's bright, beautiful and big," says retired University of Kansas professor Chip Taylor, the founder of Monarch Watch.
Taylor, who previously researched honeybees, started the project out of curiosity about the other winged pollinator's migration.
"We knew that the monarchs first reached the overwintering sites in Mexico, almost on the same day, every year, and how is that possible?" he says. "So, we came up with the idea that maybe this is all synchronized with celestial changes.
Scientists were correct and they have counted on thousands of volunteers to help figure out more information on the butterflies' journey east of the Rockies. Over a span of 30 years, they have tagged more than two million butterflies.
People who find them can enter information with Monarch Watch online. Every creature counts, since only about 1% are ever recorded dead or alive in Mexico.
Researchers found a majority of them — some 70% — come from the Midwest. And size matters.
"You don't want to be a small pipsqueak here because you don't have the glide power and glide ratio that takes advantage of thermals to get up there and sail and ride with the wind," Taylor says.
Climate change and other hazards that impact monarchs
Monarch butterfly numbers soared before wide herbicide use and the loss of habitat created a dramatic fall in the 1990s. Taylor says although he's seen steady numbers in the past decade, climate change could make the monarch migration difficult to maintain.
"Right now, we're seeing March temperatures that are much warmer in Texas. That means that the butterflies go too far north too soon, and that can have a very negative effect on how the population develops each year," Taylor says. "We're also seeing that September is getting warmer and warmer."
Monarchs don't like to travel when it's too hot. Taylor also says drought affects the food supply by preventing parched flowers from producing nectar, a monarch's food source.
"All the political bodies have to get together and say we have a problem," he says. "But aside from that, and in this country, what we can do is create more habitat."
Monarch Watch provides free milkweed seeds to help build up habitat, especially throughout the Midwest. Milkweed is the only plant monarch caterpillars eat before making the transition from a chrysalis to a full-grown butterfly.
On more than a half dozen occasions, Taylor has visited the forest in central Mexico himself, where colonies of butterflies gather during the winter.
"It can be kind of a spiritual experience," he says. "Or at least an awe-inspiring experience, if you're a biologist."
The monarch legacy
As the day ended at the DeSoto National Wildlife Refuge, the Ivey-Caldwell family counted their catch, almost a dozen butterflies.
The kids even picked up a few pointers.
"I learned how to tell the males and females apart. There are dots on the male's wings, and nothing on the females," says 10-year-old Ervin.
It's that type of hands-on participation that thrills Taylor, who at the age of 86 is planning a metamorphosis of his own. After volunteering all these years, he will soon step down as director of Monarch Watch but will continue his advocacy work. He also set up an endowment to ensure the support and appreciation for monarchs lives on.
Copyright 2024 NPR. To see more, visit https://www.npr.org.