Western Monarch Butterflies Decline By 30%: How You Can Help Protect Them

Western monarch butterflies are having a rough start to 2024. Their population has declined by a third since last year’s count, according to the latest Western Monarch count. Volunteers and scientists with the Xerces Society said they’ve tallied 233,394 western monarch butterflies at more than 256 overwintering sites in California. That's about 30% less than last year's count, which revealed around 335,479 western monarch butterflies.

Isis Howard is a biologist with the Xerces Society and joined LAist’s daily news program AirTalk. She said the number of western monarchs has declined by more than 95% since the 1980s. Howard said climate change and pesticide use have played a big role for their dwindling numbers.

"The number one factor of decline is definitely habitat loss of both their milkweed breeding ranges and their overwintering habitat," Howard said.

How to help the monarchs

Howard said even snapping a photo of a butterfly and their host plant milkweeds can help the cause. That information helps scientists better understand when and where monarchs and milkweeds are appearing in our communities.

You can submit those to the iNaturalist app or website, or to the Western Monarch Milkweed Mapper.

Thousands of monarch butterflies have returned to the eucalyptus groves dotting the coastline at the Pismo State Beach Butterfly Grove as viewed on Feb. 3, 2023, in Grover Beach, California. Because of its close proximity to Southern California and Los Angeles population centers, combined with a mild Mediterranean climate, the central coast is a popular weekend travel getaway destination for millions of tourists each year.

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But if you want to go a step further, she recommended plating native milkweeds and native nectar plants for adult butterflies.

“We want to avoid planting those native milkweeds at overwintering sites,” Howard said. You can check out websites like Calflora and Calscape to better understand which native milkweed plants grow in your region.

One note — milkweed does spread. You can plant it in a small area of your garden and remove the seed pods before they open and disperse in order to prevent them from spreading.

When do they travel?

Western monarch butterflies typically take flight during the spring.

“So a lot of monarchs are leaving their overwintering sites along the coast and starting to travel inland and more north across the United States to get back to where those milkweeds are popping up," Howard said.

These sites are typically west of the Rocky Mountains like California, Oregon, and Washington, where they spend winter.

“Monarchs rely on milkweeds to reproduce,” Howard said. “And if you think about it from a really logical standpoint, it doesn't really make sense for monarchs to be inland braving those cold winter temperatures if there's no milkweeds available because these milkweed plants will die back during winter.”

Why should you care?

Howard said monarchs serve as a sort of poster child for pollinator conservation.

She said they inspire compassion, energy, and they really get people to take action to protect other at-risk pollinators, like bees.

Typically, a monarch's decline can reflect the reduction in other insects. That result can then affect native songbirds and other mammals.

“When we think of climate change, we often think of polar bears and penguins,” she said. “When we think of pollinator conservation, we often think of butterflies and bees.”

Are monarchs on the endangered species list?

Right now, Western monarchs are not on the endangered species list. But they are listed as vulnerable on the The International Union for Conservation of Nature Red List.

“They don't have any policy or legal protections just yet,” Howard said.

But Fish and Wildlife Service could announce a listing decision later this year. Howard said that move could push them toward the endangered species list.