Pacific Swell

Southern California environment news and trends

Conservation groups seek protection of monarch butterfly

2029 full
2029 full

A group of conservation organizations teamed up with a leading monarch butterfly scientist on Tuesday to petition for protection of the monarch butterfly under the Endangered Species Act.

The monarch butterfly is one of the most iconic butterfly species in the country. But according to conservation group the Xerces Society, the monarch butterfly population is in trouble.

“Many scientists estimate that there are about 33 million monarchs. And just for comparison, in the past, researchers have estimated more than 1 billion monarchs,” said Sarina Jepsen, who directs the Endangered Species Program for the Xerces Society.

That’s a decline of about 90 percent in just fewer than 20 years, Jepsen said.

The main culprit in the monarch’s decline is the weed killer Roundup, Jepsen said. Most monarch caterpillars breed in the Midwest, and feed off of milkweed. While Roundup doesn’t kill genetically modified crops like soy and corn, it does kill milkweed.

“So, milkweed growing in a large agricultural landscape has largely disappeared in the last decade-and-a-half to two decades,” said Jepsen.

Other contributing factors include climate change and a general loss of habitat, Jepsen said. California’s drought might also play a role.

“There’s a real strong relationship between drought severity and the number of monarchs that we see in the winter on the California coast,” said Jepsen. “In years when droughts are worse, there are fewer monarchs.”

Thousands of the butterflies gather on California’s coast each winter. Spots locally includeLeo Carrillo Beach in Malibu and Doheny Beach in Dana Point, though the Xerces Society has observed a large decline in the butterflies at these locations in the last several decades.

More on the drought’s effect on the monarch population will be known around Thanksgiving, when a group of so-called "citizen scientists" with the Xerces Society perform an annual count of the monarchs.

Along with the Xerces Society, the Center for Biological Diversity, the Center for Food and Safety and leading monarch butterfly scientist Dr. Lincoln Brower filed the petition.

The Fish and Wildlife Service has 90 days to decide whether to go forward with a further review to potentially classify the monarch butterfly as threatened or endangered. 

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