Quantcast

Monarch Butterfly Population Plummets in California

Monarch butterfly on swamp milkweed. Jim Hudgins / USFWS

The population of monarch butterflies that spend winter along the California coast dropped 86 percent since 2017, according to a recent count by the Xerces Society, an invertebrate conservation group.

Preliminary results from the Western Monarch Thanksgiving Count, an annual citizen science program, recorded less than 30,000 butterflies overwintering in California, a significant decline from the estimated 192,000 in 2017. The official numbers will be released later this month.


Emma Pelton, a Xerces Society endangered species conservation biologist, wrote in a blog post that the initial results are "disturbingly low" and perhaps "catastrophic."

"While overwintering populations naturally fluctuate, even by double digit percentages, the magnitude of this year's drop is of significant concern because the monarch population was already at a new low after the 97 percent decline it has experienced since the 1980s ( Schultz et al. 2017), leading to a situation which may be catastrophic for the western population," Pelton wrote.

The 30,000 butterflies counted is the average quasi-extinction population size—or "the number of adult butterflies needed to ensure persistence of the western monarch population," Pelton explained.

It is not yet clear why their numbers were so low in 2018, although prolonged drought, a late rainy season, as well as smoke and poor air quality caused by the region's devastating wildfires could be to blame, Pelton suggested.

The latest count adds to more bad news for the iconic species, whose numbers have precipitously declined.

"In my lifetime, the monarch population in California has gone from millions of butterflies to hundreds of thousands and now, possibly, mere tens of thousands," Pelton wrote, noting that one study estimated 4.5 million monarchs overwintering in California in the 1980s.

"Next year will be a real test in how resilient the western monarch population is, after its California overwintering population has been reduced to less than 0.5 percent of its historical size," she added.

Scientists warn that the black-and-orange butterflies—known for their annual, 3,000-mile migration from the U.S. and Canada to Mexico—is at risk of extinction.

Overall, the monarch population has dropped by more than 80 percent over the past two decades. Their disappearance has been linked to climate change, habitat loss, pesticides and reduced milkweed, a native wildflower and main food source for monarch caterpillars and the only plant on which adult monarchs lay their eggs.

Despite the grim report, there are ways you can help the survival of the beloved species, which are also crucial pollinators for many different kinds of wildflowers.

"While western monarchs are facing unprecedented challenges right now, there is still hope that we can recover the population if we work quickly, strategically and together," Pelton said.

Learn more about how you can help.

Show Comments ()

EcoWatch Daily Newsletter

In tea, food, or just on your windowsill, embrace the fragrance and fantastic healing potential of herbs.

Read More Show Less

By Ana Santos Rutschman

The world of food and drug regulation was rocked earlier this month by the news of a change in leadership at the Food and Drug Administration. Commissioner Scott Gottlieb resigned and will step down in early April. His temporary replacement is Dr. Ned Sharpless, director of the National Cancer Institute.

Read More Show Less
Sponsored
MartinPrescott / iStock / Getty Images

On Wednesday the U.S. Environmental Protection Agency (EPA) announced the first 20 chemicals it plans to prioritize as "high priority" for assessment under the Toxic Substances Control Act. Given the EPA's record of malfeasance on chemicals policy over the past two years, it is clear that these are chemicals that EPA is prioritizing to ensure that they are not properly evaluated or regulated.

Read More Show Less
Strawberries top the Environmental Working Group's "Dirty Dozen" list of U.S. produce most contaminated with pesticides. DANIEL LEAL-OLIVAS / AFP / Getty Images

Which conventionally-grown fruits and vegetables in the U.S. are most contaminated with pesticides? That's the question that the Environmental Working Group answers every year with its "Dirty Dozen" list of produce with the highest concentration of pesticides after being washed or peeled.

Read More Show Less
A drilling rig in a Wyoming natural gas field. William Campbell / Corbis via Getty Images

A U.S. federal judge temporarily blocked oil and gas drilling on 300,000 acres of federal leases in Wyoming Tuesday, arguing that the Bureau of Land Management (BLM) "did not sufficiently consider climate change" when auctioning off the land, The Washington Post reported.

Read More Show Less
Sponsored
Mizina / iStock / Getty Images

By Ryan Raman, MS, RD

Oats are widely regarded as one of the healthiest grains you can eat, as they're packed with many important vitamins, minerals, and fiber.

Read More Show Less
JPMorgan Chase building in New York City. Ben Sutherland / CC BY 2.0

By Sharon Kelly

A report published Wednesday names the banks that have played the biggest recent role in funding fossil fuel projects, finding that since 2016, immediately following the Paris agreement's adoption, 33 global banks have poured $1.9 trillion into financing climate-changing projects worldwide.

Read More Show Less
Sriram Madhusoodanan of Corporate Accountability speaking on conflict of interest demand of the People's Demands at a defining action launching the Demands at COP24. Corporate Accountability

By Patti Lynn

2018 was a groundbreaking year in the public conversation about climate change. Last February, The New York Times reported that a record percentage of Americans now believe that climate change is caused by humans, and there was a 20 percentage point rise in "the number of Americans who say they worry 'a great deal' about climate change."

Read More Show Less