California Monarch Butterfly Population Down 86 Percent in One Year



California’s coast, from Bolinas to Pismo Beach, is a popular overwintering site for the western population of monarch butterflies. Historically, you could find millions of the orange and black winged invertebrates around this time of year, using coastal eucalyptus trees as shelter.

But there’s been a troubling trend over the past few decades. Each year, fewer monarchs have been showing up to overwinter on the state’s coast, according to preliminary numbers from the Xerces Society, an environmental conservation nonprofit. The group’s annual Thanksgiving count found the 2018 population of these butterflies is down to 20,456 compared to 2017’s 148,000. That’s a one year, 86 percent decline.


I used to work for a research team taking care of monarchs for their studies. They’re amazing creatures, and we barely know anything about them.

I’ve been happy to read reports of various U.S. states taking the initiative to increase the habitat availability along the Monarch Highway, as they call it. Increasing wildflowers, less mowing, fewer herbicides/pesticides, etc.

I think it’s reasonable to expect a few years of decrease as these initiatives grow, I just hope they start having some impact SOON.


I have heard from a friend in Missouri that they’ve been seeing higher numbers of monarchs in Missouri, Arkansas, and Oklahoma in recent years (like, a lot more). It’s just an anecdote from a friend, but I found it reassuring.

Following links from the NWF article led me to this great resource, which includes lots of native plant gardening tips to encourage creation of monarch butterfly habitat.