Monarch Butterfly Proposed for Listing as a Threatened Species
U.S. Fish and Wildlife Service Looks to List Species and Its Critical Habitat
A week after Goleta officials discovered just four Monarch butterflies overwintering in their Butterfly Grove at Ellwood Mesa, the U.S. Fish and Wildlife Service (USFWS) said it was proposing the iconic Lepidoptera for listing as a threatened species under the Endangered Species Act (ESA).
The environmental groups who’d petition for such a move had waited 10 years for the decision. And yet, as biologists at Xerces Society for Invertebrate Conservation said, with western monarchs facing their worst overwintering season ever in California, it came not a moment too soon.
“A lot of people are taking time to digest it,” said Xerces’s Emma Pelton of the proposed “rule.” Specifically, she said, it would provide protections and open avenues for funding, but wouldn’t prevent anyone from removing, mowing, or burning milkweed on their farm or property, a potential point of contention.
Cat Darst, assistant supervisor for Fish & Wildlife’s Ventura division, helped write the Species Status Assessment for the proposal. She explained that the inclusion of a 4(d) rule means whole lot of activities associated with enhancing milkweed and nectar sources across the butterfly’s breeding range will be allowed, as well as enhancement of overwintering habitat, but the rule would not disallow any activities that are already ongoing.
Pesticides are a separate issue, she said. “We’re asking for public comment on that.”
Challenges for Butterflies
News of the potential listing elicited a relief that would be impossible to quantify but easy to imagine. So many Santa Barbara residents find the annual return of the artful pollinator to Ellwood and neighboring coastal groves a source of joy and solace. It is by far the most recognized butterfly in North America, and maybe the most treasured, as many of our early encounters with the natural world included observing a monarch’s incredible metamorphosis in a classroom.
Where once hundreds of thousands overwintered here, last year’s count of 26,000 monarchs at Goleta’s Butterfly Grove seemed to be a rebound from 2020, when 10 showed up, and 2018 and 2019, when there were just over 200.
Fluctuations aside, the number of western monarchs has decreased 90 percent since the 1980s, when the population was in the millions. Eastern monarchs have dwindled 80 percent since the 1990s. If no action is taken, by 2080, the chances of the western monarch going extinct are 99 percent, scientists warn. The eastern monarch’s chance of extinction by that year is between 60 and 74 percent.
“What we need for monarch butterflies to do better is a significant increase in milkweed and nectar resources across their breeding range and protection and enhancement of their overwintering sites,” said Darst.
But not all milkweed is beneficial to monarchs. The planting of tropical rather than native milkweed causes problems, as the tropical species doesn’t die back in winter and allows a debilitating parasite — Ophryocystis elektroscirrha, or OE — to infect a new generation of monarchs. As well, the pervasive use of the weed-killer Roundup on farms and has virtually eliminated the native milkweed from fields that had once provided a reliable supply. Milkweed is the only plant that monarchs will lay their eggs on and the only plant their caterpillars will eat as they develop toward the pupa stage.
Climate change is another culprit in monarch losses, one that is becoming a bigger and bigger issue. A study found that one out of every two monarchs will die when exposed to constant temperatures above 96.8º Fahrenheit. Last July was the hottest month ever recorded in California, with days and days above 100ºF in the Central Valley.
Critical Habitat
In Santa Barbara County, 15 locations are identified for critical habitat designation in the proposed rule — most of them privately held.
The USFWS is legally bound to either finalize the listing, withdraw it, or do nothing by December 10, 2025. A decision to withdraw or do nothing is certain to be challenged in court by any number of environmental groups.
Meanwhile, the priorities of the incoming Trump administration add an additional layer of uncertainty to the proposal, as the President-elect has made clear his distaste for regulations. Still, Tierra Curry, a biologist at the Center for Biological Diversity, remains optimistic.
“I’m confident that if we had to challenge a decision [to withdraw] in court, we have the fact pattern to show we’re right. Also, the [monarchs] are so beloved and so popular, you would be slapping a sign on your forehead that said villain if you decided to betray them.”
A 90-day comment period is now underway. The website for commenting can be accessed at www.regulations.gov through March 25, 2025.
