Parkside Chats: 2025 Monarch Butterfly Population Count

Western monarch butterflies are one of California’s most recognizable and beloved species, gathering each winter along our coast in fragile overwintering groves.    

In our most recent Parkside Chats webinar, we were honored to speak with California State Parks Environmental Scientists Dena Spatz and Stephanie Little, alongside Emma Pelton, Senior Endangered Species Conservation Biologist at the Xerces Society, about the 2025 western monarch population count and the ongoing work to protect these iconic pollinators. 

Together, they shared the latest findings from the Western Monarch Count and explored what the data tells us about the challenges facing western monarchs. From the monarch life cycle and migration patterns to the growing impacts of habitat loss, climate change, wildfire, and invasive species, the conversation offered both scientific insight and a clear call to action. 

With approximately 50 overwintering sites located within California state parks, our public lands play a critical role in supporting monarch recovery. Through habitat assessments, management planning, restoration efforts, and cross-agency collaboration, California State Parks, California State Parks Foundation, and partners like the Xerces Society are working to ensure these coastal groves remain safe havens for generations of monarchs to come. 

Watch the full Parkside Chat Webinar 

Missed this Parkside Chat or want to revisit it? You can watch the full recording on our YouTube channel below. View the slides here. 

Monarch Q&A: Follow-Up from Our Speakers

We received so many thoughtful questions during the webinar that we weren’t able to answer them all live. After the event, we compiled your submitted questions and shared them with Dena, Stephanie, and Emma so they could respond in more detail.
 

What drove the monarch population recovery between the late 1990s and early 2000s, and can similar actions help bolster populations today?

There may be a misinterpretation of the data here – monarch numbers declined dramatically since the 90s, hovering around 200k (down from millions) and with annual natural fluctuations in populations. The population suddenly dropped in 2020 to below 10k – the lowest ever. While numbers were up for a few years after 2020, the last 2 years has seen similarly low and alarming numbers. This is why we all need to work together to reduce the use of pesticides, increase planting of native nectar plants throughout the western monarch range and milkweed for breeding, and to help to protect and restore overwintering groves along the coast. Learn more on the Xerces website: Resources - westernmonarchs.org 
 

The monarch count chart showed a spike in the early 2020s followed by a recent decline. What contributed to this change — climate impacts, habitat loss, or other factors?

We can’t say for certain what caused the decline but we know the real concern is long-term decline of monarchs and other butterflies driven by habitat loss, pesticides, and climate change. Check out this recent article about population numbers: Western Monarch Numbers Remain at Historic Low | Xerces Society 
 

What actions, if any, are recommended to address the impact of tachinid flies on monarch populations?

NA. - The only thing I would say about the tachinid flies is we don’t have much (if any) experience with them since they tend to only affect monarch caterpillars which we don’t see at our overwintering sites. 
 

How can the public identify California State Parks where monarchs overwinter and can be responsibly observed, particularly from West Los Angeles?

In the LA area, Point Mugu and Leo Carillo State Parks are a good place to find monarchs in the winter. Check out the Western Monarch Count’s public map to find an overwintering site near you: Map of Overwintering Sites - Western Monarch Count. Please be aware of public access and visitor hours when accessing a park with overwintering monarchs. 

About Parkside Chats  

It’s our newest virtual event series, designed to bring the best of California’s state parks to a wider audience and create opportunities to learn and engage.  The goal is to bring together park lovers, experts, and community voices. Parkside Chats will highlight conservation, history, climate resilience, and access to parks.  

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