The Number of Western Monarch Butterflies Is Decreasing. Starting Today, Angelenos Will Be Out There Looking For Them

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Why it matters: Monarch butterflies are the only butterfly known to make a two-way migration like birds, according to the U.S. Forest Service. But the number of Western monarch butterflies has been dwindling due to human-caused climate change, which is why scientists and volunteers have been monitoring their numbers for decades.

Monarchs' place in the ecosystem: "If we conserve the monarch, we conserve a lot of other insects as well that depend on the larval food source, the milkweed," said Richard Rachman, a plant ecologist and Los Angeles County Coordinator for the Western Monarch Count. "Monarch butterflies make a really good umbrella species to protect a bunch of others."

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What impacts the count: Western monarchs are affected by heavy rain, as well as climate change, non-native plant species and human development. Rachman said the count's coordinators are expecting to find a smaller number of butterflies compared to last year, when more than 300,000 monarchs were documented.

The backstory: Volunteers have been counting Western monarch butterflies since the 1980s, and the annual count was established in 1997. The count has allowed scientists to document a 95% decrease in the population of Western monarchs over the last four decades.

Where to see them: According to Rachman, most monarchs congregate close to the coasts, including at the Hermosa Valley Greenbelt and Ocean Avenue in Santa Monica. However, some populations have been found overwintering as far inland as Death Valley. You can see a list of Western monarch sites at westernmonarchcount.org.

How to participate: The Western Monarch Count isn't accepting more volunteers for this year, but most sites are open to the public to observe. Rachman says to look for butterfly wings (they look like clusters of Doritos) hanging from shady trees like willows, sycamores or eucalyptus trees. Here's a link to sign up to volunteer for next year's count.