Monarch Migration in the Fall

Crystal Rennicke

It’s one of the great mysteries of nature. Each fall, hundreds of millions of monarchs throughout the United States and Canada migrate to central Mexico for the winter, some traveling up to 3,000 miles. These miraculous fliers live less than 12 months and make the trip only once, yet somehow find their way back to the same fir-tree forests where previous generations have wintered for years.

The wintering grounds of these butterflies are a remarkable sight—swarms of monarchs fill the trees and the hum of flapping wings is deafening. Unfortunately, over the years, weather catastrophes and the deforestation of these grounds have taken a toll. Some statistics report a 50 to 80 percent decline over the years.  And the World Wildlife Fund has listed the monarch migration as an endangered phenomenon. Despite this, there are ways to help these amazing fliers.

The Fight for Land

In order to make a big comeback, it’s really a matter of math. Monarchs need to increase their numbers up here in the north.

“The monarch’s ability to repopulate is determined by the amount of habitat left in the United States,” says Barb Agnew, founder of the Monarch Trail in southeast Wisconsin. “Every day we lose 6,000 acres of land across the country. Developers like flat, open fields—exactly the habitat required by most butterfly species, including the monarch.”

For Barb, this hits close to home. For four years she has dedicated her time and energy to protecting one of these essential butterfly way stations on 89 acres dubbed the Monarch Trail, located in an urban area of Milwaukee. But now the city is looking to develop the site.

“The Monarch Trail was established because I needed people to witness the migration in order to convince them that this area must be preserved,” says Barb. “Monarchs need this rest area to fuel up for their long journey south in fall. It also serves as an essential roosting site for future generations.”

Barb and the supporters of the Monarch Trail have written letters and attended meetings to try to save it. While a good portion of the land will still be developed, the group did manage to get a slice of it designated just for monarchs. It was a small victory, but a big moment for Barb.

The Big Picture

Barb’s story is all too familiar. Across America, month after month, important monarch habitats are lost to land development. In the past 16 years, some 35 million acres have been destroyed, an area about the size of Illinois.

Of course, many gardeners do their part by planting milkweed, a monarch’s host plant and its caterpillars’ sole food source. But the bigger task is to preserve large parcels of land.

“Vast open areas that once supported large populations cannot be replicated in our gardens,” says Barb. “Many butterflies need specific features like wetlands and require host plants that most people don’t want in their yards.”

For example, the red admiral butterfly and tortoiseshell caterpillars feed on stinging nettle. Dill is host to black swallowtails, and pearly everlasting plants play host to American lady butterflies. These wild, weedy plants aren’t exactly backyard favorites. This is why public land is so important, Barb reiterates.  And it’s why so many people are fighting for areas like the Monarch Trail every day.

“Communities can be successful in preserving some of the natural fields and open areas for various bird and butterfly species,” Barb says.  “I believe that if the numbers rise and the land is restored, this migratory path will continue to provide a glimpse of a much larger international phenomenon.”