In mid-November 2025, researchers glued a tag lighter than a tenth of a gram onto a monarch at Moran Lake County Park and gave it a name, ML004. Two days later that butterfly was in Cambria, more than 100 miles down the coast.
Other butterflies in the same study took a shorter trip. Monarchs tagged at Lighthouse Field, including one called LF006, turned up inland at lesser-known overwintering spots on the UC Santa Cruz campus and in nearby neighborhoods. As Blake Barbaree, senior ecologist with Point Blue, put it in the Xerces Society's announcement, "This study has already shown that overwintering monarchs frequently fly across towns and cities."
Most of us picture the Natural Bridges monarchs as a park attraction. You park, walk the boardwalk, look up into the eucalyptus and drive home. According to the tracking data, the groves work as home base for butterflies that spend the winter moving across Santa Cruz. With a strong El Niño building, how this season goes depends on the groves and on the rest of town too.
The Best Count in California Came From Our Westside
The number to start with is a statewide one. The Western Monarch Count's peak survey ran from late November through early December 2025 and recorded about 12,260 monarchs across 249 sites in California. That was the third-lowest total since the count began in 1997. The two lower years are both recent: 1,901 monarchs in 2020 and 9,119 in 2024.
In that thin year, Natural Bridges State Beach logged the highest count of any site in the state, 2,500 monarchs in early December. Lighthouse Field reported 1,095 in the same mid-season count, according to the Western Monarch Count's 2025 data. Put together, those two Westside groves held close to three in ten of all the monarchs counted in California that season.
Even so, a long-time volunteer remembers much bigger numbers. Natural Bridges docent Kirk Crane told KAZU this month, "We had 120,000 in 1997. You'd go through that grove down there, and they would just be roped with huge clusters the size of you and me." So last December's 2,500 was the best showing on the coast, and it was also about 2% of what the same grove held in the late 1990s.
The Xerces Society calls Natural Bridges, Lighthouse Field and Moran Lake the three most important overwintering sites in Santa Cruz County. It adds that in recent years they have held the highest numbers of overwintering monarchs anywhere on the California coast. That's why the tagging study happened here.
What the Tags Revealed About the Rest of Town
The study was a partnership between the Xerces Society, Point Blue Conservation Science, California State Parks and Santa Cruz County Parks. The tags are BlūMorpho transmitters from Cellular Tracking Technologies, weighing 0.06 to 0.07 grams, with a tiny solar panel and a short antenna. Older monarch tags were heavier and needed specialized receivers. These new ones can be picked up by ordinary phones and tablets with Bluetooth and location turned on.
That design choice matters for people who live here. During the study, anyone could download the Project Monarch app, which turned their phone into a mini receiver that tracked tagged monarchs in real time. Xerces said that opened the door to hundreds or even thousands of detections per tag. The project's story map lists stationary receivers at Lighthouse Field, Natural Bridges, Moran Lake, Escalona Gulch and South Branciforte.
Xerces's Spring 2026 Wings follow-up says the Santa Cruz monarchs were tracked through February. Thousands of detections are revealing how the butterflies move between groves and through towns. Two butterflies tagged at Lighthouse Field, LF043 and LF006, were picked up inland around UC Santa Cruz.
Barbaree drew the practical conclusion in the Xerces release. Since monarchs cross our streets all winter, "we can help overwintering monarchs at home and in our communities by planting pesticide-free flowers that provide nectar." Xerces keeps a California monarch nectar plant list for exactly that.
Why This Winter Has Biologists Watching the Sky
NOAA's Climate Prediction Center, in its October 8, 2026 discussion, says El Niño is strengthening. It gives a greater than 83% chance of strong to very strong conditions through January to March 2027. NOAA also cautions that El Niño-type impacts aren't guaranteed.
Monarchs choose these groves partly because the trees block the wind. In the same KAZU story, Rhiannon Sims of the Santa Cruz District of California State Parks said that protection has limits. "If we have a big storm that comes through, sometimes even being in the grove isn't enough to protect them." Isis Howard, a conservation biologist at the Xerces Society, said, "We're concerned that this winter could damage groves, result in more monarch mortality than we've seen in past seasons." KAZU also noted that it's not yet clear how this El Niño will play out locally.
So the timing of a visit matters more than usual this year. The weeks before winter storms set in may be the most dependable time to see full clusters.
Timing a Visit Around the Butterflies' Schedule
On October 11, when Friends of Santa Cruz State Parks held this year's Welcome Back Monarchs Festival, KAZU found monarchs only starting to reach the coast. Last year's early-season count gives a sense of how fast that changes. Natural Bridges reached 1,100 monarchs by October 29, 2025, and Lighthouse Field had 979 by November 1, 2025.
The sources differ slightly on the best window. California State Parks says late October through November is often a good time to visit. A park docent quoted by Visit Santa Cruz County puts the typical peak in late November and early December. Last season's 2,500 count fell in early December, which fits the docent's window.
Whether you see clusters or butterflies in flight mostly comes down to temperature.
- Clusters: State Parks says monarchs cluster in the Natural Bridges eucalyptus below 60°F. The Xerces Society's visiting guide recommends cool early mornings or overcast days for clusters.
- Flight: Xerces suggests sunny mornings or afternoons above 55°F to catch monarchs in the air. The docent cited by Visit Santa Cruz County also puts the flight threshold at about 55°F.
Treat those numbers as rough ranges, not exact cutoffs. A gray Westside morning followed by a sunny lunch hour can give you both views in one day.
Here are the practical details for Natural Bridges this season:
| Item | What's posted |
|---|---|
| Park hours | 8 a.m. to sunset |
| Visitor center | 11 a.m. to 4 p.m. daily, October 1 through January 31 |
| Vehicle day-use fee | $10 |
| Boardwalk access | Wheelchair- and stroller-accessible to an observation deck |
| Next festival | Migration Festival, listed for February 13 |
California State Parks doesn't post a time for the Migration Festival yet, so check closer to February. The grove rules are simple. Don't touch or harm the butterflies, keep your voice down, and keep dogs, bikes, skates and skateboards off the boardwalk. Xerces adds a few more requests. Stay on the paths and behind barriers, leave the plants alone, and don't use sprays in the grove.
Lighthouse Field is the other half of this Westside pair. It's a California State Beach on West Cliff Drive. Its count tracked close to Natural Bridges early last season, and its grove was one of the three tagging sites.
Counting Them Yourself This Year
If you'd like to do more than visit, the Western Monarch Count runs on volunteers. For 2026, the early-season count runs October 17 to November 1, so it's in its final days when this post goes up. The mid-season period, which used to be called the Thanksgiving Count, runs November 14 to December 6. The late-season period runs December 26, 2026 to January 10, 2027.
You have to register every year through the count's volunteer page. Plan on 12 to 15 hours, including virtual and in-person field training, surveys at an assigned site, and coordination with a regional coordinator. During the tagging study, Xerces said count volunteers sped up data collection by visiting overwintering sites regularly to count monarchs and look for tags.
Last winter, tagged monarchs from Lighthouse Field turned up at overwintering sites on the UC Santa Cruz campus and in the neighborhoods around it. A pesticide-free yard planted from the Xerces nectar list puts food along routes the butterflies are already flying.
At The Portola Group, we love that the most-watched monarchs on the California coast spend their winter on our Westside, and that the rest of town turns out to matter to them too. If this season has you thinking about your own garden, your street or the home that comes with them, we're happy to talk it through. Get your instant home valuation whenever you're ready, and we'll see you on the boardwalk.
