The Fish and Wildlife Service proposed listing the monarch butterfly as a threatened species Tuesday in one of the most highly anticipated actions ever taken under the Endangered Species Act.
Prompted by a 2014 petition and subsequent litigation from environmental groups, the federal agency has determined that the monarch requires federal protections — albeit with some management flexibility that has yet to be fully defined and with a designated critical habitat that’s limited to parts of coastal California.
While the Fish and Wildlife Service found that the monarch has been in decline, it is found across all the lower 48 states. The butterfly’s ubiquity has made the ESA decision particularly challenging, as FWS officials try to protect a charismatic species that — with protections — could stand in the way of all sorts of development projects.
“We’ve never listed a species that occurs in all 48 states and can occur from the small urban backyard to rangeland in the Southwest or in Texas and the California coast. It can touch anywhere,” Lori Nordstrom, the Fish and Wildlife Service’s assistant Midwestern regional director for ecological services, said in an interview.
By proposing to list the monarch as threatened rather than endangered, FWS can attach so-called 4(d) rules that provide exemptions from the normal outright ban on harming or killing species listed under the ESA. The agency is soliciting public suggestions on potential 4(d) rules that could allow exemptions for activities that might include agricultural pesticide use.
FWS is also proposing to designate as critical habitat 4,395 acres in California where the Western monarch population overwinters. Nordstrom described the designated area as a mix of public and private lands that sprawl across seven counties.
Critical habitat is not a reserve or refuge, but federal agencies that seek to fund or authorize projects on land or water designated as habitat must consult with FWS or NOAA Fisheries, depending on the species.
The more abundant Eastern monarch population overwinters in Mexico, which is outside the bounds of potential critical habitat designation.
The listing to be formally published in the Federal Register on Thursday kicks off a 90-day comment period, with the next steps to be taken by the incoming Trump administration.
The proposal specifies some 4(d) exemptions, including injuring or killing monarchs due to vehicle strikes and the nonlethal collection for possession or research of 250 or fewer monarchs per year.
When it comes to more potentially controversial exemptions, such as for wind farms, infrastructure projects or pesticide use, FWS didn’t come to any final conclusions but is asking for public input.
“Pesticides are such a complex issue,” noted Jake Li, the Fish and Wildlife Service’s assistant director for ecological services. “There are questions about which pesticide active ingredients to possibly cover, and which pesticide uses and which pesticide application methods. So if you combine all of that, you have thousands of permutations.”
Li added that when combined with EPA’s ongoing work on pesticide registrations, “we still need some time to figure out” how to handle the relationship between pesticides and monarches and “that’s why we’re really seeking public comment at this point.”
The Center for Biological Diversity, Xerces Society and Center for Food Safety filed the initial petition on the monarch’s behalf.
The Center for Biological Diversity and Center for Food Safety followed up with a lawsuit.
FWS declared in 2020 that adding the butterfly to the list of threatened and endangered species was “warranted but precluded by work on higher-priority” ESA responsibilities. In a subsequent settlement, the federal agency agreed to make a monarch decision by the end of 2024.
“Monarch butterflies are in a dire situation and desperately need protection under the Endangered Species Act,” Stephanie Kurose, deputy director of government affairs for the Center for Biological Diversity, said earlier this year. “These fragile butterflies bravely undertake one of the most epic migrations in the animal kingdom. It would be devastating to witness this migration collapse.”
Steve Blackledge, the Sacramento-based senior director of conservation campaigns for Environment America, said earlier this week that a proposed ESA listing “gives us hope” that future generations can enjoy the butterfly.
“For too long, the monarch butterfly has been waiting in line, hoping for new protections while its population has plummeted,” said Blackledge.
The Western monarch population is geographically distinct from Eastern monarchs. The latter migrate from eastern Canada and the United States to central Mexico each year. The Western population migrates from the western United States and Canada to coastal California and northern Baja, Mexico, as well as a few smaller sites.
“The Eastern population, by far, has always been much, much larger than the Western population, but our models for the likelihood of extinction is that by the year 2080 the Eastern population has a 40 to 72 percent chance of extinction, so it’s pretty darn high,” Nordstrom said, adding that “the Western population is so small that by 2080 it has a 99 percent chance of extinction.”
FWS cites conversion of grasslands to agriculture, widespread use of herbicides, urban development, continued exposure to insecticides and the effects of climate change as the primary threats to the monarch’s future.
Most especially, monarchs need the milkweed plant on which they feed and lay their eggs. Ongoing milkweed conservation efforts that might get a boost from the new listing proposal include a Chicago-based “candidate conservation agreement with assurances” program that recruits energy companies and government agencies to boost habitat on rights of way.
Still, scientists have voiced mixed opinions about the overall health of the species.
FWS cites data such as that from the Xerces Society for Invertebrate Conservation, which has found the overwintering population of Western monarchs remains at approximately 5 percent of its size in the 1980s.
But other scientists have asserted the butterfly is actually doing relatively well. An influential paper published in 2022 challenged pessimistic assessments of monarch populations. Researchers in 2023 successfully prodded the International Union for Conservation of Nature to remove the migrating monarch butterfly from its “Red List” of endangered species.
Nordstrom acknowledged the competing research about the species. “We look closely at the stats, we look closely at our modeling, and according to all that information … we felt that it met the definition of a threatened species,” she said.
The monarch proposal was a nationwide effort for the FWS team, which included experts from California, Michigan, Minnesota and the District of Columbia.
Inside the agency, officials have already established a Center for Pollinator Conservation, which was itself announced at a first-of-its-kind monarch summit convened on Capitol Hill in June 2022.
“I’d say most listed species don’t get that level of attention,” Li noted, “so I think it’s very fair to say that this is a very high priority for Interior.”
Correction: The original version of this story incorrectly identified one of the organizations that filed a lawsuit seeking endangered species protections for the monarch. It was the Center for Biological Diversity and Center for Food Safety.
