For over 25 years, The Xerces Society has led the Western Monarch Count, a community science effort dedicated to tracking the migratory western monarch butterfly population. Each year, volunteers and conservation organizations conduct surveys at overwintering sites along the Pacific coast—from Mendocino County, California, to Northern Baja, Mexico—and at inland sites in Arizona and California’s Saline Valley. During the 2024-2025 season, over 400 volunteers and partners participated in the effort, surveying over 250 overwintering sites and recording a peak population of just 9,119 monarch butterflies.
The latest count marks a sharp decline compared to the past three years when annual reports consistently recorded over 200,000 monarchs. Researchers believe that in the 1980s, more than 4.5 million monarch butterflies spent the winter in California (Schultz et al. 2017). While we don’t know the exact threshold, Schultz et al. 2017 suggest that at least 30,000 butterflies is the minimum population needed to ensure the western migration survives.
Several key factors influence the annual variation in monarch numbers, including temperature, rainfall patterns, habitat availability, and habitat quality. For more details about the 2024-2025 season count, check out The Xerces Society’s announcement by clicking here.
Tracking these population trends helps emphasize the need for conservation efforts that support monarchs throughout their entire lifecycle. Key conservation strategies include:
Plant native milkweeds- Find more information on where to locate native milkweeds and other native wildflowers to support monarchs and other pollinators on our Milkweed Vendor Map.
Participate in Community Science Programs—Learn more about community science programs in your area. Please note that, according to the California Department of Fish and Wildlife, you must have a scientific collection permit to handle monarchs in California.
Educate others about monarchs and pollinators and how they can help. One great way to become a monarch ambassador is to take one of our online courses.
Limit pesticide use that may cause unintended harm to monarchs and other beneficial insects. Learn more about pesticides and monarchs.
The MJV would like to thank our network of partners, volunteers, and fellow pollinator conservation community, who work tirelessly to help conserve and protect monarchs, other pollinators, and the ecosystems they inhabit. Together, we can sustain the monarch migration and conserve other plants and animals that share their habitats.