WALNUT CREEK, CA — The monarchs are starting to think about the coast again, and the people who count them are asking Walnut Creek to keep an eye on the sky.
Every fall, the western monarch butterflies that spent the summer drifting around the East Bay begin a slow, unhurried push toward the groves of the Central Coast — Pacific Grove, Pismo Beach, Santa Cruz, the places where they’ll cluster by the thousands and wait out the winter. Their route runs straight through our open space, over the foothills of Mount Diablo and down through Shell Ridge and Lime Ridge.
Here’s the thing: there aren’t many of them left to watch.
The 29th annual Western Monarch Count, run by the Xerces Society, turned up roughly 12,260 monarchs across 249 overwintering sites last winter. That’s the third-lowest tally since the count began in 1997 — and the second straight year the population has sat at historic lows.
So conservationists are asking residents to report monarch sightings ahead of this year’s count, which happens around Thanksgiving and again around New Year’s. It’s citizen science of the lowest-effort kind — no lab coat required, just a phone and a minute.
What You Can Do
None of this requires turning your backyard into a nature preserve. Three small things move the needle.
How to Help the Monarchs
Report what you see. If a monarch lands in your yard or drifts across the Iron Horse Trail, log it on iNaturalist or the Western Monarch Milkweed Mapper. Every sighting tells researchers where the butterflies still are — and where they’ve gone quiet.
Plant native milkweed. Monarchs lay their eggs on milkweed and nothing else. The native narrowleaf milkweed (Asclepias fascicularis) is the one that belongs in a Contra Costa garden. Skip the tropical stuff — it hangs around too long in the fall, and scientists say it can scramble the migration and spread disease.
Go easy on the pesticides. The monarchs and every other pollinator on your block will thank you.
Where to Look This Fall
You do not need a permit or a preserve to spot one. The monarchs move across the open space that rings town, so the same ridgelines locals already walk are the best place to look:
- Shell Ridge Open Space — the trails on the north side of downtown, warm and open.
- Lime Ridge — the ridgeline east of Ygnacio Valley Road.
- Iron Horse Trail — an easy one for a lunchtime walk with your phone out.
- Warm, still afternoons through October are when they are most likely to be on the move.
And look — Walnut Creek matters in this story. Shell Ridge and Lime Ridge, the ridgelines that frame downtown, are exactly the kind of stopover habitat monarchs need on their way west. The city has spent years stitching its open space together with trails, and a butterfly corridor is a decent side benefit of all that work. If you’d rather see wildlife up close than squint at a butterfly, Lindsay Wildlife Experience up in Larkey Park has been doing that work for decades.
The count is coming. The butterflies are moving. Keep your phone handy — and if you see one, say so.
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