New Tracking Technology Reveals Monarch Butterflies' Journey from Wisconsin to Mexico

After a nearly 1,400-mile flight, Snickers has made it, WPR reported. And so have David, Nancy, Otto and Bug.

They are among the monarch butterflies tracked by the Southern Wisconsin Bird Alliance since September when researchers tagged them in Wisconsin. Their long journey ends in Mexico, and new tracking technology shows that several of the insects have crossed the finish line.

The Southern Wisconsin Bird Alliance glued 30 solar-powered radio tags onto the backs of monarch butterflies at Goose Pond Sanctuary in Wisconsin’s Columbia County, about 20 miles north of Madison. Since then, researchers have followed their migration patterns using the Project Monarch app.

The app detects monarchs in real time. Snickers was detected 944 times across seven states before crossing the Mexico border.

Tiny trackers help researchers follow monarch migration from Wisconsin to Mexico — WMTV | News, Weather & Sports

“There was never really a way to track an individual and see what the migration path is like on an individual basis, so being able to do that on that scale with a whole collection of monarchs is really, really powerful,” said Brenna Marsicek, the director of outreach at Southern Wisconsin Bird Alliance.

Marsicek said that monarch migration will continue into December, but 10 of the organization’s tagged butterflies have already reached Mexico. One butterfly traveled an even greater distance.

“So Nancy, one of the butterflies, flew over 1,770 miles between Goose Pond and where it is now in Mexico, where it’ll overwinter,” Marsicek told WPR.

New Tracking Technology Reveals Monarch Butterflies' Journey from Wisconsin to Mexico — Photo: ironmountaindailynews.com

However, 14 of the tagged monarchs have not been spotted by the app in more than a month.

“They might resurface, they might just be in a really remote part of the country and not pinging against phones, or it could be that they’re dead,” Marsicek said. “Either way, it’s interesting data to know approximately how many butterflies actually make it into Mexico.”

Wisconsin monarch migration: 15 tagged butterflies reach Mexico — HeyDay News

Tagging the insects aims to improve conservation efforts by providing a clearer understanding of migration patterns. Marsicek said that some butterflies unexpectedly flew north to Minneapolis before heading south, a detour researchers theorize was caused by eastern wind patterns.

“It was just a really interesting revelation that a butterfly would go that far in sort of the wrong direction before continuing their migration,” she said. “It’s been a really powerful tool for us to learn about this species that’s in major decline and needs some really significant help from us to be able to persist into the future.”

Once they arrive in Mexico, monarchs rest in the oyamel fir forests, which sit nearly 2 miles above sea level and provide an ideal microclimate.

Farther south, observers tracked the arrival as it unfolded. On November 4, Journey North received a dispatch from Estela Romero detailing butterflies flying above the compact community of Angangueo Michocan. On November 22, the El Rosario and Sierra Chincua sanctuaries inside the Monarch Butterfly Biosphere Reserve officially opened their gates to visitors.

In Wisconsin, the last monarch reported to WisconsinButterflies this year was on November 5 in Milwaukee County, though that butterfly had emerged with deformed wings. Observer Lindsey Dalton logged the final healthy monarch of the season at Madison’s Olbrich Botanical Gardens on November 4.

Researchers plan to analyze the full data set after the migration period ends to shape conservation strategies for 2027, with the Southern Wisconsin Bird Alliance preparing to tag more butterflies next summer.