Proposed listing aims to keep monarch numbers from fluttering away

Federal wildlife officials are proposing to list the monarch butterfly as a threatened species due to population declines, and researchers in Wisconsin hope it will prompt more conservation of monarch habitat.

Eastern monarchs, the largest migratory population in North America, have declined 88 percent from its population of 383 million during the mid-1990s. The population of western monarchs is down more than 99 percent from roughly 4.5 million in the 1980s.

The proposal from the U.S. Fish and Wildlife Service will be decided by the end of this year under a new administration. During Donald Trump’s first term as president, the agency found the monarch’s listing was warranted, but other species were deemed a higher priority at the time.

Each year, eastern monarchs embark on a migration spanning thousands of miles and multiple generations to overwintering grounds in Mexico. But the iconic orange and black butterflies are facing threats from habitat loss, climate change and the use of insecticides, according to Lisa Nordstrom, the federal agency’s Midwest assistant regional director for ecological services.

“This small, small insect can migrate from here, Wisconsin and Minnesota, all the way down to Mexico, a place where they’ve never been, just their great, great grandparents were there,” Nordstrom said. “Hopefully, we don’t ever have to get close to contemplating that sort of a future that doesn’t have monarch butterflies in it.”

The agency’s most recent assessments found there’s a 56 to 74 percent chance the eastern population may go extinct by 2080. The likelihood of extinction is almost certain for western monarchs.

Listing seeks to encourage more flexibility to restore habitat

The proposed listing aims to encourage more flexibility under the Endangered Species Act for people to restore habitat by planting milkweed and flowers on the edges of fields, around buildings and in their backyards.

Milkweed was once abundant among corn and soy, but the use of herbicides killed the plants to enhance crop yields. The proposal would allow current farming and grazing practices to continue, but seeks to avoid further conversion of grasslands that would result in the loss of monarch habitat.

Tyler Wenzlaff, national affairs director for the Wisconsin Farm Bureau Federation, said the group is closely examining the proposal.

“Wisconsin farmers have been leading the country in adoption of conservation practices and doing buffer strips and planting pollinator gardens in areas,” Wenzlaff said. “With the listing, in Wisconsin, we’re asking our farmers to continue to practice (conservation efforts), and we expect those areas to grow. Hopefully, we see the numbers of monarchs rebound.”

Over the past four years, the federal agency and partners have worked with landowners to restore more than 3,600 acres of habitat to benefit monarchs and other pollinators in Wisconsin.

Karen Oberhauser, professor emeritus of entomology at the University of Wisconsin-Madison, has been studying monarchs since 1985. She noted the number of monarch butterflies varies widely from year to year driven mostly by weather conditions that have become more extreme due to climate change.

“What we want to do is make the ceiling, or the top of those fluctuations, higher than it has been,” Oberhauser said. “Right now, the population is so low that there’s a chance that, in any given year, a catastrophic event could send monarchs spiraling to a point from which they might not be able to recover.”

Monarch butterflies dropped to near record low in 2023

In 2023, the iconic orange and black butterflies dropped to a near record low. Colonies of monarch butterflies occupied only 2.2 acres of forest at overwintering grounds in Mexico, according to Wayne Thogmartin. He’s a research ecologist with the U.S. Geological Survey at the Upper Midwest Environmental Sciences Center in La Crosse.

Thogmartin monitored monarchs last winter at Piedra Herrada, which is typically the 3rd largest overwinter colony in Mexico.

“We should see monarchs draped on the branches of the oyamel fir forest down there in the millions in a typical year,” Thogmartin said. “We went to the very top of the mountain (and) didn’t see any monarchs.”

He said a string of climatic events year after year could result in the loss of the monarch migration. One recent analysis showed a 50-50 chance of such loss in the next two decades.

Thogmartin and other researchers have evaluated more than 200 scenarios for restoring greater than 1.3 billion stems of milkweed to rebuild their population. Without substantial participation from agriculture, efforts are not enough to restore their numbers because farm lands make up 77 percent of all potential habitat.

Oberhauser said researchers and groups like the Wisconsin Monarch Collaborative are underscoring the need for habitat restoration in Wisconsin.

“The nice thing is that anyone that has a backyard can help monarchs, so we’re really trying to encourage individual action,” Oberhauser said. “This can be on people’s own land if they have land that’s available to them, or it can be at their church or their school or where they work.”

As climatic events vary across their range, Oberhauser said it’s crucial to see plantings everywhere. Nordstrom with the Fish and Wildlife Service added it will bring cascading benefits to not only monarchs, but other pollinators.

The agency is accepting public comments on the proposed listing through March 12.