This story is part of our November 2025 issue. To read the print version, click here.

The monarch butterfly window has opened at Natural Bridges State Beach in Santa Cruz.

Through January, the only state-run monarch preserve in California becomes a magical stop for the overwintering western monarch butterflies, where the striking black-and-orange winged insects cluster by the hundreds in the shady eucalyptus tree groves, seeking shelter from the wind. Just a short walk from the visitors center parking lot and ample picnic benches is the 300-foot-long, wheelchair-friendly Monarch Grove Trail that winds down into the canyon, allowing visitors to get within feet of the monarchs and enjoy the magic firsthand.

Look closely, or you might miss the monarchs huddled in the trees, where they blend in with the foliage. Some do break away, however, and interact with visitors. One may even land on an outstretched finger.

The 65-acre park, which also features a beach, tide pools with a natural sandstone arch, prepares year-round for the arrival of fall, kicking off the season with the 45th annual “Welcome Back Monarchs Day” celebration on Oct. 12, according to Martha Nitzberg, an interpreter with California State Parks.

Once the butterflies show up, Nitzberg says, they’ll be self-guided and staff-led tours during the 6 a.m. to sunset park hours. Before arriving at overwintering sites like Natural Bridges, western monarch butterflies migrate from areas west of the Rocky Mountains, including parts of the western U.S. and Canada. The eastern monarch population, meanwhile, migrates from Canada and the northern U.S. to overwinter in Mexico.

Meanwhile, the western monarch butterfly population is in peril. Last January, the Xerces Society for Invertebrate Conservation released the results of its annual Western Monarch Count for 2024, and the peak population was reported of just 9,119 monarchs in sites located along the California coast, northern Baja California and a few inland sites in California and Arizona.

It was the second lowest overwintering population ever recorded since tracking began in 1997, Emma Pelton, senior endangered species conservation biologist with the Xerces Society, says from Xerces’ headquarters in Portland. California State Parks also play a crucial role in determining the western monarch population with their yearly counting events.

“Right around Thanksgiving, we do a count up and down the county to see how many butterflies there are for the year,” says Nitzberg, who adds there’s a similar count around New Year’s Day.

Natural Bridges, one of the top four western monarch migration sites (there are about 250 sites where monarchs are usually found), had 1,400 monarchs last year — a huge drop from the 120,000 that were counted there in 1997, Pelton says. Other top sites include nearby Lighthouse Field State Beach, with 1,406 monarchs, and Pismo State Beach, with 556.

Western monarchs are proposed to be federally listed as “threatened” under the Endangered Species Act, and before last year’s count, the western monarch population seemed to be coming back, with almost 233,000 butterflies counted in 2023-2024. However, Pelton says there have been a few encouraging signs heading into this fall.

“We’re going to have a lot more of a picture around the end of the month (October),” Pelton says. “Based on what we’ve been seeing just on iNaturalist —  which has really become the best way to look at comparing year to year — the late summer and early fall actually look better than they did last year, so we’re starting to feel cautiously hopeful that we’re going to be above the really low numbers we saw last year.”

According to the Natural Bridges webpage, reasons for the decline of monarchs are loss of natural habitat and the use of pesticides and insecticides. People wanting to help the monarch population can plant milkweed and other nectar sources, such as marigolds, cosmos and asters.

Pelton says last year’s extreme heat and historic drought were also factors for 2024’s steep decline.

“We really saw, actually, a pretty good spring generation (in 2024), and then in the summer, they just kind of disappeared,” Pelton says.

In addition to the monarchs, Nitzberg says,  there are other species to see in the eucalyptus trees at Natural Bridges, including horned owls, who have been calling the Natural Bridges’ eucalyptus grove home for several years.

Beyond the 0.6-mile monarch loop, visitors can explore a variety of trails which offer views of the coast and native plants. From these trails, hikers can access Lighthouse Field State Beach and visit the Santa Cruz Surfing Museum inside the Mark Abbott Memorial Lighthouse, as well as tidepools teeming with shorebirds, migrating whales, seals and sea otters.

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