Skip to main content

Western Monarch Thanksgiving Count Tallies Over 330,000 Butterflies Before Storms Batter Overwintering Sites

By Isis Howard and Emma Pelton on 31. January 2023
Isis Howard and Emma Pelton

For the 26th year, community scientists grabbed their binoculars and ventured out to survey monarch butterflies for the Xerces Society’s Western Monarch Count. Surveying a total of 272 overwintering sites across coastal California and a few sites in interior California and Arizona, volunteers tallied 335,479 monarch butterflies during this year’s Thanksgiving Count which ran November 12- December 4, 2022.


Graph tracking total monarchs reported and number of overwintering sites monitored for the Western Monarch Thanksgiving Count from Nov. 1997 to Dec. 2022. Populations have bounced over the years, with an overall decline from the late 90s. Following a steep decline in the late 2010s, numbers for the last two years mirror counts from 200-2017. Number of sites monitored have generally increased over time.
Total monarchs reported and number of overwintering sites monitored for the Western Monarch Thanksgiving Count from Nov. 1997 to Dec. 2022.


Season highlights

Motivated by a surprising rebound in 2021, volunteers' excitement continued to grow when early reports hinted at a consecutive year of improved numbers. 2022 ended up being the biggest volunteer engagement year yet, with over 250 people participating and a return to in-person trainings after limited opportunities during the pandemic.

The largest individual monarch count was 34,180 at an overwintering site in Santa Barbara County owned by The Nature Conservancy. (The site is not open to the public.) The second largest count was 25,710 butterflies at a private residential site in Santa Barbara County. Pismo State Beach Monarch Butterfly Grove had the third largest monarch count and is open for public viewing, with 24,128 butterflies reported at its peak.

As is typical, the Central Coast continued to host a majority of the largest sites and overwintering monarchs, with over 130,000 butterflies reported in both Santa Barbara and San Luis Obispo Counties. The Bay Area witnessed a comeback from last year with more than 8,000 butterflies reported in surrounding counties such as Alameda, Marin and Solano. 

Additionally, seven newly-recognized overwintering sites were included this season, hosting a combined total of over 15,000 butterflies. 


Monarchs cluster together on a branch
Monarchs clustering on Monterey Pine at Pacific Grove Butterfly Sanctuary in November 2022. (Photo: Isis Howard / Xerces Society.)


While the numbers are hopeful, this isn’t yet population recovery

This season’s results are a welcome reprieve from a total of less than 2,000 individuals counted in 2020 and even modestly larger than the nearly 250,000 in 2021. 335,479 is squarely back into what was considered “normal” in 2000-2017.  However, even with these relatively good numbers, migratory western monarchs have still declined more than 90% since the low millions seen in the 1980’s and 1990’s. 

“We can all celebrate this tally,” says Emma Pelton, a conservation biologist at the Xerces Society and western monarch lead.  “A second year in a row of relatively good numbers gives us hope that there is still time to act to save the western migration. That said, we know we still have a long way to go to reach population recovery and the storms that hit right afterwards mean we’ll start the spring with far, far less than this total.”

Dr. Elizabeth Crone, professor and quantitative ecology at UC-Davis, likens the changing numbers to trying to predict traffic lights. “Given two relatively good years in a row, it’s tempting to think that the rate of change in monarch populations might have suddenly switched from decreases to increases. However, this kind of change is hard to detect for insects like monarchs, because for butterflies – like many insects – the yearly rate of change varies a lot from year to year.”  

“When something varies a lot, it takes a while to know the overall trend.  Think about driving down a highway – if you see two green lights in a row, do you assume they are all green and keep going through the next ones without looking? Probably not.” Dr. Crone explains more in her blog that gets into the nitty-gritty of the math behind western monarch population estimates and trends.


Graph that estimates western monarch populations accounting for increasing survey efforts. Graph shows that numbers for the last two years are consistent with numbers from 2000 to 2017, with a steep decline between.
Western overwintering population estimate accounting for survey effort from 1980-2022 on a log-scale.

Updated from Crone, E.  & Schultz, C. 2021. Resilience or Catastrophe? A possible state change for monarch butterflies in western North America. Ecology Letters, 24(8), 1533-1538.


The decades-long decline is due in large part to threats such as habitat loss at the overwintering sites and breeding grounds, exposure to pesticides, and the compounding effects of climate change. Much work is now underway to reverse some of these stressors, particularly through planting milkweed and nectar plants, by a wide range of people such as agencies, everyday native plant and monarch enthusiasts, NGOs, and tribes. 

These small but collectively powerful changes to rewild our landscapes for monarchs and other wildlife are deeply inspiring. The challenge now is ramping up these efforts to a much bigger scale and engaging in the harder issues like pesticide use, climate change resilience, and doing the slow, important work of protecting and restoring hundreds of overwintering sites.


How are monarchs faring after the storms?

While we know that monarchs are resilient creatures, the overwintering butterflies have already experienced historically intense storms this winter. Back-to-back atmospheric rivers drenched most of the California coast between late December and mid January, negatively impacting many overwintering sites. Volunteers and partners submitted reports of flooding, downed tree limbs and even entire trees uprooted, like this one at Pismo State Beach Monarch Butterfly Grove. Many publicly-owned overwintering sites, including Pismo, are once again open to the public for viewing after being closed during the winter storms.  


Several uprooted fallen trees
Eucalyptus trees uprooted along the creek at Pismo State Beach Monarch Butterfly Grove in January 2023. (Photo: Stephanie Little / California State Parks.)


The storms also greatly limited volunteers' ability to survey monarchs during the New Year's Count, which ran December 24, 2022 through January 8, 2023. It is likely that far fewer monarchs will be reported for that count (which is still being tallied) as seasonal decreases of 35-50% are common even in years without extreme storms. At some sites, butterflies were blown out of their clusters, making them more vulnerable to cold, wet conditions and predation. All of this will negatively impact this spring’s breeding population, but how big of an impact is yet to be seen. 

Other sites, like Pacific Grove, fared relatively well with the majority of monarchs still holding on. With the weather calming down, many volunteers are now getting out for an extra late season count or habitat assessment to help document the impact of the storms on the butterflies and their habitat. 

“Small populations are particularly vulnerable to being snuffed out by extreme weather, so we are lucky these storms occurred in a relatively good year,” said Pelton. “We don’t want to count on luck alone to ensure the survival of the western monarch migration.”


Monarch hangs on to wet leaf in the rain
Monarch clinging to a eucalyptus leaf in the rain. (Photo: Nancy Merrick / Western Monarch Count volunteer.)


Protecting and restoring overwintering groves is crucial

The storms also emphasize that protecting and restoring overwintering groves is crucial. Managing groves to be more resilient to climate change and severe weather may help improve monarch survival and ensure there is habitat long into the future. This can include replacing dead and dying trees, planning to prevent or mitigate flooding, planting native nectar sources, and making meaningful policy changes and enacting legal protections. Continued advocacy, action and support are needed now and well into the future.

“Unfortunately, there continues to be very little meaningful protection for the species or its habitat. Overwintering sites in particular continue to be destroyed and damaged each year," says Isis Howard, a conservation biologist with The Xerces Society and coordinator of the count.

While migratory monarch butterflies were declared endangered on the IUCN Red List of Threatened Species last summer, they are not yet listed under U.S. or state Endangered Species Acts, which would afford the species legal protections. A federal listing by the U.S. Fish and Wildlife Service is anticipated in fiscal year 2024.

“The plain fact is that if we lose overwintering sites in California, we could lose migratory western monarchs. Development, eucalyptus removal, and tree trimming all need to be managed thoughtfully if we are to leave space for these animals to survive" says Howard.


In memoriam

We are mourning the unexpected death of longtime Western Monarch Count volunteer and much-loved colleague Dan Meade on November 26th at the age of 68. Dan was a monarch overwintering expert and co-founder of Althouse and Meade, Inc. Dan worked for decades on western monarch conservation, especially the protection and management of some of the most important overwintering sites, including this year’s top three sites.


How you can help

Here are five actions you can take to support monarch butterflies: 

  1. Plant native milkweed.
  2. Plant a diversity of nectar plants, ideally native to your area. 
  3. Stop using pesticides, or minimize risk associated with pesticide use.
  4. Call on legislators to support greatly needed policies such as Recovering America’s Wildlife Act and the Monarch Action, Recovery, and Conservation of Habitat Act.
  5. Contribute to community science projects that track monarchs, such as the Western Monarch Milkweed Mapper, Western Monarch Mystery Challenge, and nationwide Integrated Monarch Monitoring Program.

The Xerces Society has been active in monarch and pollinator conservation in California for decades. Xerces' work helps restore monarch overwintering sites, expand pollinator habitat on farms, and has distributed more than 130,000 pollinator plants through Xerces’ Habitat Kit Program. This program provides plants to partners creating habitat in working lands, public lands, and tribal lands. Project proposals for the California kits will be accepted starting February 21, 2023.


About the Western Monarch Count

The Western Monarch Count is a volunteer-powered community science effort run by the Xerces Society and count co-founder, Mia Monroe, to count overwintering monarchs and assess their habitat. It is centered around the Thanksgiving holiday and runs for a three week period. The Thanksgiving Count is designed to collect data on the status of the migratory western monarch population each fall using a standard protocol to estimate the number of butterflies clustered at overwintering sites. (A second count period occurs around the New Year’s holiday and lasts for two weeks; the results of that count will be announced in February.) 



A huge thank you to the more than 250 dedicated volunteers who collected data at overwintering sites. And, thank you to our western monarch conservation funders, who make this work possible: Bureau of Land Management, California Department of Fish and Wildlife, California State Parks Foundation, California Wildlife Conservation Board,, Forest Service International Programs, The Marion R. Weber Family Fund, Monarch Joint Venture, National Fish and Wildlife Foundation, Natural Resources Conservation Service, San Diego Zoo Wildlife Alliance, The Taggart Saxon Schubert Fund, US Fish and Wildlife Service, and Xerces Society members.



As the Xerces Society's western monarch lead, Emma works on the western population of monarch butterflies, including adaptive management of overwintering habitat in California and breeding habitat throughout the western U.S. Emma completed a master's degree in agroecology and entomology at the University of Wisconsin–Madison where her research focused on landscape ecology and an invasive fly that affects fruit crops.

As an endangered species conservation biologist, Isis works in California to protect and support the western population of monarch butterflies. She manages several community science projects, including the annual Western Monarch Count and the Western Monarch Milkweed Mapper, and provides support to land managers and the public on maintaining and restoring western monarch breeding habitat.

Your Support Makes a Difference!

Xerces’ conservation work is powered by our donors. Your tax-deductible donation will help us to protect the life that sustains us.