Experts fear extinction as California's monarch population plummets

Yahoo

17-02-2025

The Western population of the monarch butterfly has declined to a near-record low with fewer than 10,000 found living in the US state of California this winter, a foreboding sign for the future of the beloved black-and-orange insect.
An annual count recorded 9,119 butterflies this winter, according to results released by the Xerces Society for Invertebrate Conservation. This is the second-lowest population recorded since tracking began in 1997. An all-time low of fewer than 2,000 monarchs was recorded in 2020.
The society said these numbers underscored the importance of the US Fish and Wildlife Service's new proposal to list the butterfly as a federally endangered species.
The butterfly's Western population has plummeted more than 95% since the 1980s, when up to 4 million butterflies were estimated to spend winter in California, according to the California Department of Fish and Wildlife.
Without urgent conservation efforts, the US Fish and Wildlife Service estimates that the Western population faces a 99% chance of extinction by 2080.
Habitat destruction, pesticides and extreme weather fluctuation due to climate change are all to blame for the butterfly's decline.
This year's particularly poor showing can also be attributed to an usually hot and dry fall, which probably slowed butterfly breeding and the metamorphosis of caterpillars into butterflies, said Emma Pelton, an endangered species biologist with the Xerces Society.
Los Angeles-area wildfires wiped out habitats
At a local level, the recent Los Angeles-area wildfires damaged tree groves where these butterflies live, including a habitat site in Lower Topanga Canyon where more than 100 butterflies were recorded in last year's count, she said.
Another alarming finding was made at a site in Santa Barbara County, which went from recording 33,200 monarchs last winter to only 198 this year.
The count is conducted by about 400 volunteers at 257 sites along California's coastline and Baja California, Mexico, where the Western monarch population gathers to pass winter before fanning out across the West from Arizona to Idaho in spring.
The Eastern monarch population — which has decreased more than 80% since the 1980s — spends winters in the mountains of central Mexico and warm months in the eastern half of the United States, according to the US Fish and Wildlife Service.
This year's Western monarch count marks a sharp decline from the last three years, when more than 200,000 Western monarchs were recorded each year, thanks, in part, to more favourable weather conditions, said Pelton.
But even counts in the 200,000 range mark a dangerous decrease from the millions of butterflies observed in the 1980s that scientists consider a stable population level.
"Insect populations commonly fluctuate from year to year," according to the California Department of Fish and Wildlife. "The overall downward trend remains concerning, particularly if the threats are not ameliorated."
Calls to list monarch as endangered species since 2014
The monarch butterfly was first petitioned to be listed under the federal Endangered Species Act in 2014, but that effort was shelved due to more urgent population priorities.
In late 2024, the US Fish and Wildlife Service released a proposal to list the butterfly as an endangered species.
"The iconic monarch butterfly is cherished across North America, captivating children and adults throughout its fascinating lifecycle. Despite its fragility, it is remarkably resilient, like many things in nature when we just give them a chance," said Martha Williams, then-director of the Fish and Wildlife Service, in a December statement.
"Science shows that the monarch needs that chance."
The service has also proposed designating 4,395 acres as critical habitat for the Western monarch population across Alameda, Marin, Monterey, San Luis Obispo, Santa Barbara, Santa Cruz and Ventura counties to help support population regrowth.
The service will be accepting public comments on the proposed threatened species designation and make a final decision by the end of 2025.
More pesticide regulation needed to save monarch
In addition to supporting the designation, the Xerces Society is urging the US Environmental Protection Agency (EPA) to take into account the effect of pesticides on butterflies before approving the products for market.
Currently, the only insect included in the EPA's required pesticide testing is the adult honeybee.
Testing by the Xerces Society and the University of Nevada-Reno found that milkweed leaves, the main food source for the monarch caterpillar, were contaminated by 64 pesticides. One of these pesticides, methoxyfenozide, was found in 96% of milkweed samples, but it is allowed to be used under current pesticide regulations because it is not toxic to bees.
"We know pesticides are a key driver of monarch and other pollinator declines. Yet there are glaring gaps in the EPA's oversight of pesticides: the vast majority of pesticides have never been tested for their impacts on butterflies," said Rosemary Malfi, director of conservation policy at the Xerces Society, in a statement.
"How can we protect these essential species if we're missing the basic information needed to make better decisions?"