Western monarch butterflies | Cal Parks

Western monarch butterflies

The western monarch is arguably one of the most recognizable butterflies in California. Monarchs are known for their vibrant orange and black wings and unique long-distance, multi-generational migration cycle. Hundreds of thousands of monarch butterflies on the forested groves of the Pacific coast stretching from Mendocino County, California to Baja to overwinter. In the 1980s, an estimated 4.5 million butterflies migrated to the coast annually. However, by the mid-2010s, the population declined to 200-300 thousand butterflies. In 2018 and 2019, volunteers counted under 30,000 monarchs — less than 1% of the population’s historic size. In 2020, volunteers counted less than 2,000 monarchs — that’s less than 0.01% of the historic size. While the 2021 count was overwhelmingly positive, the population has still plummeted from historic numbers.  

The California state park system holds critical habitat for western monarchs – providing shelter and protection for this iconic species. Many state parks are home to key monarch overwintering sites located along important migration routes. These places offer the appropriate microclimate conditions for clustering, provide nectar resources, and minimize stressors to the butterflies. 

Through our western monarch butterfly initiative, we have invested in improving western monarch butterfly overwintering habitat “Monarch groves” by supporting the implementation of state parks approved Grove Management plans.  

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California state parks western monarchs

How you can help monarchs