How to Help Save Western Monarch Butterflies in California

Understand what western monarchs need, and discover four meaningful ways to support them.

If you’ve been to a local butterfly roost, you’ve likely seen the awe-inspiring display: garlands upon garlands of western monarchs clustering together in a coastal grove. These orange-and-black beauties have just completed one of nature’s most remarkable migrations, traveling hundreds or even thousands of miles to spend winter in our corner of the state.

If western monarchs seem less abundant in our region than they did years ago, you’re not mistaken. In the 1980s, millions overwintered along California’s coast. In 2025–26, community scientists recorded approximately 12,260 western monarchs, the third-lowest count since monitoring began in 1997 and part of an alarming 99% decline.

While no single garden or volunteer effort can solve widespread threats like habitat loss, pesticide use, and climate change, coordinated habitat protection and individual actions both matter. Read on to learn more about western monarch butterflies and the practical steps we can take to help their populations rebound.

MEET THE WESTERN MONARCH

In late summer and fall, a remarkable generation of western monarchs takes flight. Unlike earlier generations, which live only a few weeks, these migrants can survive for six to nine months. They delay breeding — a state called reproductive diapause — and undertake a journey they have never made before.

Guided by environmental cues, some travel from Oregon, Idaho, Nevada, and Utah to coastal California. Rather than tiring themselves out with wing-flapping, they conserve energy by riding favorable air currents, reaching sheltered groves by late October and clustering in trees through February. Want to see some western monarchs in person? Here are our top spots.

As winter ends, they mate and leave the coast. Females lay eggs on emerging milkweed, and successive short-lived generations continue the journey north.

4 WAYS YOU CAN HELP

1. Grow nectar plants (for hungry adult monarchs)

The science: Adult monarchs need diverse nectar sources throughout their lives. This sugary liquid supplies the energy they need for migration, reproduction, and everyday activity. Nectar shortages along their migratory routes can affect how many successfully reach overwintering sites.

What to do:

• Plant a selection of native species with overlapping bloom periods.
• Prioritize spring and fall flowers—and winter-blooming species near the coast—when nectar is especially important.
• Plant flowers in clusters that butterflies can locate easily.
• Leave some seed heads, stems, and leaf litter to support other pollinators too.
• Avoid using pesticides that can harm butterflies and other pollinators.

2. Grow native milkweed (for hungry caterpillars)

The science: Native milkweeds are essential host plants for monarchs. Adult butterflies lay their eggs on them, and the caterpillars that hatch eat nothing else. As caterpillars feed, they store defensive compounds called cardenolides, which make many monarchs distasteful or toxic to predators.

California is home to several native milkweed species. These herbaceous perennials can grow in gardens and containers, but choosing a locally appropriate species — and giving it the right conditions — is essential.

• Select a plant that’s native to your location. Narrowleaf milkweed is one of California’s most widespread and commercially available native species, but it may not be right for every site. Take a peek at Calscape or consult a regional milkweed guide before selecting a plant. 
• Avoid tropical milkweed. Because it may remain green through winter in California, tropical milkweed can disrupt normal migratory behavior and allow a harmful monarch parasite called OE to accumulate.
• Avoid planting milkweed near coastal overwintering sites. North of Santa Barbara, experts recommend against planting milkweed within five miles of known overwintering groves or in places where it did not historically grow. Milkweed in these locations could interfere with normal migratory behavior. When milkweed is not appropriate, choose native nectar plants that bloom across seasons instead.

3. Help steward overwintering sites

The science: In the wintertime, not just any stand of trees will do. Western monarchs need groves with a particular blend of wind protection, moisture, filtered sunlight, and moderate temperatures. They cluster together in this sheltered microclimate and remain relatively inactive, occasionally taking flight on warmer days to find nectar or water. As winter ends, they start reproducing and begin leaving the coast.

Of all the roosts within the state, there are many here in the Bay Area that have designated viewing areas where you can take in the migration responsibly. Additionally, the organizations, volunteers, and communities who are working to manage and protect these locations need our support. You can pitch in by donating, volunteering, or joining a local stewardship group.

 4. Become a community scientist

The science: Monarch conservation depends on knowing where butterflies breed, feed, migrate, and overwinter, and how those patterns change. Community scientists keep a lookout for monarchs and milkweed, collecting data to monitor the decline or recovery of the species.

What to do:

• Participate in the Western Monarch Count.
• Report milkweed and monarch observations to the Western Monarch Milkweed Mapper.
• Join a local habitat-restoration project.
• Support protection and thoughtful management of overwintering sites.

SMALL ACTIONS ACROSS A VAST RANGE

It’s true that western monarch recovery requires suitable habitat across an enormous range. But taken collectively, thousands of gardens, protected groves, restored pesticide-free landscapes, and informed communities can give each new generation the resources to continue the journey.