As they go through ecological ‘uncharted territory,’ the time to see migrating monarchs is now

They’re lying down, flat on their backs, like sunbathers at the beach on the Fourth of July. But it’s December, and we’re in the dark and shady (and quite chilly) grove of eucalyptus trees at Natural Bridges State Beach on the Westside of Santa Cruz, lying on cold wood planks. What gives?

Well, it turns out there’s an ideal way to experience the monarch butterflies this time of year, newly arrived from their migration to their customary overwintering spot at Natural Bridges. And that’s from a supine position. Sure, you can stand there and gaze up at the fluttering butterflies above your heads. But that’s no better in watching the monarchs than in contemplating the Big Dipper. Soon, after a minute or two, you’re going to feel it, too. You’re going to need to lie down.

Just as it is in spots all up and down the California coast, the onset of winter brings a tradition to Santa Cruz that has nothing to do with our all-too-human holidays. This is the time of year that the monarchs gather in big numbers in specific places like the grove at Natural Bridges, the only state monarch preserve in California, and a bit down the street on West Cliff Drive at Lighthouse Field. They begin arriving in November and stick around through to the end of February for many of the same reasons that, say, Canadians migrate to Puerto Vallarta — namely to evade the cold and follow the sun.

“They’re usually all here by Thanksgiving,” said Natural Bridges ranger Estrella Bibby on a recent clear chilly afternoon. “But this week is fantastic [for viewing the monarchs]. When the weather’s like this, it’s perfect. They’re super-active today. I spent all morning down in the grove and they’re hanging in big clusters that are really obvious to see.”

For many native and longtime Santa Cruzans, that doesn’t exactly qualify as news. Seeing the monarchs at Natural Bridges has been a calendar touchstone for generations. And in recent years, the arrival of monarch season has been accompanied by one overriding question: How many of them are here this year?

In 2020, monarch migration populations dropped precipitously to a historical low of around 2,000 butterflies — not at Natural Bridges, but total from the hundreds of migration spots along the California coast. In more recent years, however, that number has rebounded substantially. Last year, the count tallied more than 330,000 butterflies. 

‘Resilient’ monarchs

So, what’s the story for 2023-24? The results are not yet in for the Western Monarch Count, which takes place every year around Thanksgiving (and again at New Year’s). Early estimates, however, suggest a slight increase in the monarch population specifically at Natural Bridges, but a decrease in the larger Western range. The final tally for the Western Monarch Count is expected in January.

“We haven’t finished tallying the data yet,” said Isis Howard of the Xerces Society, the Oregon-based conservation organization that conducts the annual counts, “but this year, we’re seeing numbers not as low as the record lows of 2018 through 2020, but lower than the past two years. We’ve got over 100,000 butterflies for sure. But we’re just not sure if we can reach 200,000.”

If those numbers hold up, they represent a deviation from the narrative of the bounceback of 2021-23. The paltry numbers recorded in 2020 led to the monarch’s status to be classified as “endangered” by the International Union for Conservation of Nature. But, in September, in light of the improved numbers of the past two years, the IUCN backtracked on that designation, reclassifying the migratory monarch as “vulnerable.” 

Still, in an even larger context, the populations of migratory monarchs have taken a dramatic dip from the numbers seen in the latter part of the 20th century. As late as the 1990s, the number of Western monarchs migrating from inland areas to coastal overwintering spots was in the millions. At its lowest point in 2020, the monarch population represented a 99% decline from the 1980s.

“That caused a lot of concern for monarch experts,” said Howard.  “But last year, we exceeded 300,000, and the year before we exceeded 200,000. So we know that butterflies, and monarchs specifically, are resilient. It’s also typical to see invertebrate populations, especially butterflies that are at risk, kind of bounce around in this uncharted territory. So while we want to remain cautiously optimistic that we can support monarchs on their path to recovery, this is not recovery just yet.”

What accounts for the evidence that populations are down this year in relation to 2022? Howard said that it’s common for monarch populations to fluctuate, but “one thing that we can look to as a possible factor in this year’s lower numbers is the severe winter storms that we experienced last winter.”

A Natural Bridges tradition

While Natural Bridges isn’t the only site in Santa Cruz County where monarchs gather in the winter months, the state park has built a culture going back generations about the annual migration. Not only has the park constructed a boardwalk-style pathway into the monarchs’ favorite grove, it staffs the area with volunteer docents and park employees during the park’s open hours, has designed programs and exhibits on the migration and life span of the monarchs, and has hosted school groups of local students to gaze upon the butterflies for decades. That’s why there are generations of now-adults who grew up in Santa Cruz and who remember the days when the trees at Natural Bridges were weighed down by large clusters of orange-and-black butterflies.

The park, in fact, hosts a community event each October to welcome the monarchs to town, which has been going on for more than 40 years, and another in February to say farewell to not only monarchs but all migrating creatures as they move on to their next landing spot. 

Martha Nitzberg is the go-to person for all things monarchs at Natural Bridges. “We’ll see these people come,” she said, “and they’re now middle-aged, and they’ll say, ‘When I was a kid, they had these [butterfly] costumes …’ and I say, ‘Yep, we still have those costumes.’”

Nitzberg said that docents are crucial to the butterfly viewing experience, mainly because visitors, especially first-timers, aren’t sure where to look, or what they’re looking at. In recent years, the park has even installed an electronic wifi-enabled screen that provides a live close-up of the monarchs at rest on a tree limb.

And why do butterflies migrate hundreds of miles from all over interior California and other parts of the interior West? As you might guess, they are (1) following the sun — overwintering monarchs are rarely found more than a half-mile from the coast — and (2) they’re tracking milkweed, their main food source, the availability of which along the coast allows them to survive the winter.

The magic of monarch migration stems from the realization that the life cycle of any one individual butterfly is much too brief to include more than one such migration. That means every butterfly that comes into Natural Bridges — or Lighthouse Field, or Pacific Grove — is arriving for the first time (unlike those snowbirds in Mexico), coming to the very same spots that their forebears had visited. 

“These butterflies who are clustering along our coast,” said the Xerces Society’s Howard, “have never been to these particular overwintering sites. And scientists are still wondering, how do they find the same grove, the same trees, the same branches on those same trees, even though they are generations removed from the last butterflies who clustered there? It’s incredible. It just kind of underscores the magic and mystery of these creatures.”

The monarch grove at Natural Bridges State Beach is open 8 a.m. to sunset, and the visitors center is open 11 a.m. to 4 p.m. every day except Tuesdays and Wednesdays. Admission is free, but there is a $10 day-use fee for vehicles. 

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