Few monarch butterflies show up at migration
Smaller turnout: Habitat degradation, pesticides and wildfires are partly to blame
Pacific Grove this time of the year usually draws thousands of visitors in search of clusters of western monarch butterflies. The city is among several locations along the Central Coast, including Santa Cruz’s Natural Bridges State Beach and Lighthouse Field, known as great places to view the spectacular display.
But as insect populations plummet worldwide, there are few if any monarchs to see in “Butterfly Town, U. S. A.” this year. Their disappearance from winter habitats is part of a larger vanishing act of all western butterfly species that is altering California’s landscape in unknowable ways.
“This is nothing but a tragedy — not just for Pacific Grove but for us as a society,” said Bill
Peake, the city’s mayor.
Scientists say butterfly populations throughout the western U.S. have been dropping dramatically over the last two decades — a consequence of habitat degradation, pesticide use and intense wildfires linked to climate change.
Early data from the annual Western Monarch Thanksgiving Count, led by the Xerces Society for Invertebrate Conservation, shows that the monarch population has fallen to another record low — fewer than 10,000 monarchs compared with millions during the 1980s and 300,000 just five years ago.
The Xerces Society reported on Nov. 30 that only 1,224 monarchs had been counted by volunteers at that point in the tally — 550 of them at Natural Bridges State Beach.
The butterflies have become so scarce that the U.S. Fish and Wildlife Service is now deciding whether to list the monarchs under the U. S. Endangered Species Act.
“We’re likely on the verge of losing some butterflies locally or regionally,” said insect ecologist Matthew Forister of the University of Nevada, Reno. While those at-risk butterflies are not about to become extinct worldwide, he said, “that could change over the next 30 to 50 years.”
Forister’s recent research suggests that the warming planet is hastening the widespread butterf ly declines across the West.
Because butterflies are cold-blooded, the increasing temperatures raise their metabolism, making food shortages much more acute. At the same time, the butterflies’ nectar sources are getting harder to find as plants wither in the heat.
Heat is also responsible for dry vegetation — a catalyst for this year’s devastating wildfires, which have consumed butterfly habitat across the West.
Arthur Shapiro, an ecologist at UC Davis, has witnessed the devastating effects of the wildfires on butterflies firsthand. Shapiro has been monitoring 10 field sites across the state of California since 1972. And he has created the largest butterfly database in North America and one of the
largest in the world.
One of Shapiro’s sites in Solano County is now completely gone and is unlikely to significantly recover for at least three to five years, he said.
In the High North Coast Range, a million acres have burned, mainly in the Mendocino National Forest, home to numerous rare plants that host butterflies.
“Many of the most important butterfly habitats have been lost, including some that harbored exceedingly rare species at the edges of their ranges,” Shapiro said.
Small- scale fires are often beneficial to butterflies, which love open spaces. But the scale and intensity of California’s recent wildfires destroyed important habitats and didn’t give butterflies enough time to move. As a result, only the most widespread and mobile species may be able to recolonize afterward.
Some species may be gone for good, Shapiro said. Two species new to science, the Bald Hills Satyr and one species so new that it hasn’t been named yet by scientists, were spotted in only a handful of localities, all of which have burned.
Other issues are also driving their decline. In coastal California, oncepopular over w inter ing sites are disappearing because of relentless development. And herbicides and insecticides used by everyone from homeowners to large corporate farms not only directly harm butterflies but also destroy essential nectar resources.
Emma Pelton, a conservation biologist with the Xerces Society, and other monarch experts agree that it’s unlikely the beloved butterflies will disappear as a species. But they say it’s a strong possibility that California will lose them as they gravitate to parts of North America where the weather is warm year-round — places such as southern Texas and Mexico. Most of the monarchs who now overwinter in California spend their summers in western states with cold winters.
Faced with the devastating losses, conservationists are urging the public to help with their efforts to restore butterfly habitats.
Cheryl Schultz, a conservation biologist at Washington State University, is part of a group of researchers that recently called “cit
izen scientists” to action.
Schultz has been studying at-risk butterflies since the early ’90s and more recently has begun research on western monarchs.
Between the winters of 2017 to 2019, she saw California’s monarch populations plunge from 200,000 to under 30,000. Based on her data, Schultz knew that the drop occurred following the wintering period, but before the beginning of the main breeding season.
She suspected that something was going on between these two periods in the early spring. But not much is known about where monarchs go after leaving their wintering sites.
“Monarchs are a needle in a haystack,” Schultz said. “But there are a lot of people in California. Maybe we can figure out a way to engage the public to help us.”
In an attempt to solve the puzzle, she helped launch last spring’s Western Monarch Mystery Challenge. It encouraged participants to take photos of the monarchs they spotted outside of their overwintering groves and upload them to iNaturalist, a free online platform. Citizen science efforts such as this one help give conservationists a clearer picture of which habitats and resources butterflies need to thrive.
The Xerces Society organizes a variety of other ef for ts. T he organization works to restore butterf ly habitats by giving away plant kits. And the nonprofit also works with farmers and ranchers to put monarch habitats on their land, and it helps California State Parks restore overwintering sites along the coast.
“Butterflies in California have a lot stacked against them,” Pelton said. “The scale of declines we’re seeing in these animals really means we need to take action.”
Pelton and other biologists say Californians can take action right in their backyards by planting flowering plants that provide nectar year-round as well as avoiding the use of pesticides.
The future of butterflies may look grim, but “insects really are survivors,” said the University of Nevada’s Forister. “We will lose some for sure, but if we can smarten up our agricultural practices and rein in climate change a bit, then there’s a lot of hope.”