Monarch Butterflies Have Begun Their Migration

Thursday, September 18th, 2025 -- 9:01 AM

(Royce Podeszwa, Wisconsin Public Radio) The colorful monarch butterflies are just starting to make their 3,000-mile journey across North America. 

The flutterers spend the fall and summer living, breeding in and passing through Wisconsin. But the head of a local monarch monitoring community group said they’d soon begin their journey to overwinter in Mexico.

Karen Oberhauser is the former director of the University of Wisconsin-Madison’s Arboretum and cofounder of the Monarch Larva Monitoring Project. She has four decades of experience researching monarch butterflies.

Oberhauser said that at this point in the monarch season, the butterflies are still living and breeding in northern ranges as far north as Canada, but she added that the earliest generation of migrators to Mexico are now about halfway to their destination.

She highlighted a monarch migration tracker site that maps the butterflies through community inputs as they make their way thousands of miles to the forests of Mexico.

“I just looked at those maps and I see some monarchs are showing up now in roosting sites way down in Kansas and even a little bit further south right now,” she told WPR’s “Wisconsin Today.” 

In the 2023-24 season, monarchs nearly hit an all-time population low, according to the World Wildlife Fund, or WWF. This year, Oberhauser said she expects to see numbers rising due to the region’s higher rainfall and lack of drought.

But the total population remains at risk from climate change, pesticides and habitat loss. WWF reported that monarchs covered 4.42 acres of Mexico’s forests last year.

That’s down from the nearly 45 acres covered in 1996-97.

Feel free to contact us with questions and/or comments.