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Western Monarch

Western Monarch butterflies make a spectacular annual migration of up to 1,500 miles to overwinter in forested groves along the coast of California, but even these stalwart travelers need our help. Sadly, the Western Monarch butterfly population has been drastically declining over the last few decades. The Riverside-Corona Resource Conservation District is working to reverse these trends, but we need the community’s help.

A monarch butterfly caterpillar on a green plant with a blurred background.
Monarch caterpillar on native milkweed. Photo by Michele Felix-Derbarmdiker

Why the Shocking Decline?

·       Loss of Native Milkweed: Milkweed is the only food source for the Monarch caterpillar, and much of it has been destroyed due to land being converted from habitat to agricultural or urban use.

·       Pesticide Exposure: Monarchs are weakened and killed unintentionally by toxic weed and insect killers.

·       Drought and Climate Change impact milkweed growth and habitat availability.

·       Disease: Many nurseries sell tropical milkweed which does not go dormant in winter. This tropical milkweed can host a parasite called Ophryrocystis elektroscirrha, or "OE" that weakens and kills Monarchs.

·       Coastal Habitat Loss: Coastal overwintering sites have been degraded or developed, leaving few trees that provide for quality roosting sites. Monarchs need tall trees like Eucalyptus, Monterey pine, and Cypress that provide filtered sunlight for warmth and protection from wind.     

Efforts of the RCRCD:

In Spring of 2020, the RCRCD received a grant from the Wildlife Conservation Board and the California Association of Resource Conservation Districts, to establish 2 acres of Monarch breeding and foraging habitat. In addition, funds were allocated towards community education on the plight and conservation efforts related to Western Monarchs. 

RCRCD staff member releases tagged monarch butterfly
RCRCD staff member releasing tagged monarch butterfly

Once millions of Monarch Butterflies would overwinter on the Pacific West Coast but their population has been on a drastic decline since the 1980's. In the winter of 2020, less than 2,000  monarchs were counted at overwintering sites. This drastic decline is due many factors including loss of habitat, pesticide use and climate change. With the population at just 1% of it's historic size, is is now critical to take the appropriate actions to support Monarch populations.

We have a long uphill battle to save the Monarch, but through community education and outreach, partnerships and conservation efforts, the RCRCD will continue to strengthen our endeavors. In addition to our 2 acre foraging and breeding habitat site in Riverside, the RCRCD has also launched the 1, 2, 3...for the Butterflies and Bees Program, makes native plants available to the public for purchase, added native milkweed at appropraite restoration sites and works in partnership with the Southwest Monarch Study to collect, rear, tag and test monarchs . This will be an on-going effort. Join our efforts by adding native nectar plants, including native milkweed to your gardens or become a community scientist and help gather critical data on local monarch popultions.

Come to the Rescue!

Plant Native Milkweed: Locally, adult Monarchs lay their eggs on Narrow Leaf Milkweed, Asclepias fascicularis. The caterpillars grow rapidly, increasing their weight almost 3,000 times in 10-15 days. The flowers also provide nectar for adult butterflies. Native milkweed will go dormant around Halloween and re-emerge around Valentine’s Day. Don’t weed it out if it appears dead. Learn more at Steps for Success with Milkweed and Monarchs for Inland Southern California Valleys: https://www.rcrcd.org/files/65eb89ba5/2020_Monarch_Milkweed_for_SoCal.pdf

 

Eliminate Pesticides: Use nontoxic alternatives for pest control. https://www.rcrcd.org/files/92cdf50b3/Natural+Pest+Control.pdf

 

Grow Flowering Plants, especially natives that provide nectar in early Spring and Fall.  Avoid planting tropical  milkweed.

 

Track Monarchs: Please avoid captive rearing and instead collect and post data online at  Western Monarch Milkweed Mapper, iNaturalist and many other community science platforms. Be on the lookout for the four life stages: egg, caterpillar, pupa and adult.

Learn more:

The Monarch Recovery Project wouldn’t be successful without broad community engagement, plus state and national support.