Tag | Xerces Society

Western Monarchs

Many monarch butterflies landing on the branches of a tree at an overwintering site.

Everything You Need To Know About Visiting Overwintering Monarchs

A remarkable phenomenon unfolds along the California coast each fall — and you can witness it yourself!

Monarch caterpillar on narrowleaf milkweed (Asclepias fascicularis). (Photo: Xerces Society / Stephanie McKnight)

Keep Monarchs Wild: Why Captive Rearing Isn’t the Way to Help Monarchs

Instead of rearing—which is risky and unproven in helping monarchs—we should focus on more effective, science-backed ways to conserve these glorious wild animals.

Monarchs aggregating on a tree at one of their overwintering sites

Despite a Lower Peak Season, Western Monarchs Start Spring in Higher Numbers than 2023

Migratory western monarchs underwent a 28% seasonal decrease this winter before dispersing from overwintering sites.

Western Monarch Count Tallies 233,394 Butterflies

The overwintering population of western monarchs remains at approximately 5% of its size in the 1980s.

Top 5 Ways Californians Can Help Western Monarchs

Residents of California are uniquely positioned to help western monarchs, since monarchs are found in California all year long and in all life stages.

Milkweed seeds in a bin and in someone's hands

Growing the Supply of Hard-to-Find Milkweeds

Great Valley Seed shares the process of growing rare but important milkweed species to supply them for the first time.

Why Monarchs Need Early-Season Milkweeds

Western monarchs need milkweed for breeding as soon as they leave their overwintering sites. That's why we partnered on a project to make early-season native milkweed more available in California.

Monarch Wishing Tree holding up hundreds of wooden butterflies

California Garden Center Leads by Example with Monarch Wishing Tree

Each spring a beautiful ficus tree transforms into something extra special for the folks that visit Roger’s Gardens plant nursery. The Monarch Wishing Tree displays hundreds of well wishes written on little wooden butterflies that support conservation.

New Year’s Count of Western Monarchs Reveals High Seasonal Decrease Following Severe Winter Storms

The Xerces Society’s Western Monarch New Years Count data reveals a 58% seasonal decrease in the overwintering western monarch population. While numbers are expected to decrease between Thanksgiving and New Years for various reasons, this decrease is higher than trends over the last six years.

Western Monarch Thanksgiving Count Tallies Over 330,000 Butterflies Before Storms Batter Overwintering Sites

The numbers are in for the Xerces Society’s 26th annual Western Monarch Thanksgiving Count! Volunteers reported a final tally of 335,479 monarch butterflies. These numbers inspire hope but species recovery remains vulnerable to pressures like habitat loss, pesticide use and climate change. Already, severe storms have taken a toll since the count.

Clusters of overwintering monarchs on a tree branch

The Current Status of Western Monarch Butterflies, By the Numbers

Volunteers reported another relatively high number of overwintering western monarch butterflies this year, but we don't have enough steady information yet to confirm a statistically significant trend.

Attendees of the Monarch Butterfly Summit at the U.S. Capitol Visitor Center in Washington, DC. (Photo: Scott Black/ Xerces Society)

D.C. Monarch Summit Secures Funding for Monarch Conservation

Last week, myself, Sarina Jepsen, and Sarah Hoyle of Xerces joined a two-day Monarch Butterfly Summit at the U.S. Capitol Visitor Center in Washington, DC. Hosted by Oregon Senator Jeff Merkley in collaboration with the Department of the Interior, the event brought together key stakeholders to discuss solutions to reverse the declining monarch butterfly, particularly the western monarch population.

Man poses with California Habitat Kit plants in truck during pickup. Credit: Angela Laws.

Meet the Partners Saving Pollinators with Xerces’ California Habitat Kits

Over the past three years, Xerces’ California Habitat Kit program has given away over 105,000 plants to partners all across California who are interested in creating habitat for monarchs and other pollinators. We’ve been able to work with some really great people as part of this program who have helped to create habitat in a variety of landscapes.

Western monarchs overwintering in California 2021-2022 (Photo: Jessica Griffiths)

New Year’s Count of Western Monarchs Tracks Population Decline During Overwintering Season

The Western Monarch New Year’s Count serves as a follow-up to the annual Thanksgiving Count to help scientists better understand how the western monarch population changes throughout the overwintering season. Monitoring revealed an average decrease of 38% between the Thanksgiving and New Year’s Counts, within the range of a 36-49% seasonal decline observed over the previous six winters. The overall western monarch population remains higher than in previous years.

Volunteers count monarchs in Pacific Grove Monarch Butterfly Sanctuary, December 2021 (Photo: Candy Sarikonda)

Western Monarch Thanksgiving Count tallies nearly 250,000 butterflies

The Xerces Society’s Western Monarch Thanksgiving Count celebrates its 25th year of community science with a surprising and remarkable outcome: 247,237 monarch butterflies observed across western overwintering sites, an over 100-fold increase from last year.

Monarchs at a private overwintering site in Monterey county, CA

The Bounciness of Butterflies

The western monarch migration is having a better year, but this isn’t population recovery.

Two women stand beside a farm field. One has a black shirt and pale brown pant. The other black pants and a pale brown shirt and is wearing a broad-brimmed hat and carries an orange bag. A strip of brown grass stretches down the edge of the field. Beside the field is an orchard of trees with white trunks and green leaves. In the distance is a green barn and houses with red roofs, and beyond them hills rising toward the blue sky.

The Value of Conservation Planning

Land owners and managers across the state of California have taken up the call to get more habitat in the ground for monarchs. But there’s one important process that comes into play prior to on-the-ground restoration: before we can plant, we plan.

A photo of a desert landscape. In the background, brown hills dotted with green shrbs rise toward the blue sky. In the foreground, flowers are in bloom. A row of low shrubs coverd in white flowers stretches away from the viewer toward a clump of short trees.

Climate News: Nature-Based Climate Solutions Address Climate Change and Support Pollinators

Habitat restoration can contribute to countering climate change. Native trees, shrubs, flowers, and grasses increase carbon sequestration, while also providing habitat for butterflies and bees.

A cluster of several dozen orange-and-black monarch butterflies rest on the branches of a pine tree

Applying a Holistic Approach to Monarch Conservation

Xerces is a science-based conservation organization and our work on monarchs is no different. Whether it is restoring overwintering sites in California, creating breeding habitat in New York State, or protecting monarchs from pesticides, science informs our actions and maximizes our conservation return.

Two orange-and-black monarch butterflies drink nectar on yellow-and-red colored flowers. The flowers are tropical milkweed, a non-native plant that should not be grown to help monarchs.

Resident Monarch Populations on the Rise in California: What Does this Mean for the Western Migratory Population?

Many people have been seeing and reporting fairly large numbers of monarchs, both adults and caterpillars, all winter long in gardens on the California Coast this year. Since there haven’t been any formal studies of the number of monarchs breeding during the winter in California in prior years, it is difficult to know if there is in fact an increase this year, or if people are paying more attention and reporting them more often.

Graph showing results from surveys of overwintering monarchs in California. The number of monarchs has fallen for several years, so the height of the bars gets shorter and shorter to the right of the graph

Fifth Annual Western Monarch New Year’s Count Confirms Continued Decline in Western Monarch Population

Now in its fifth year, the New Year’s Count has given us a better understanding of: 1) how monarch numbers may decline at overwintering sites as the winter progresses; 2) how monarchs move between and within sites; 3) when they leave sites; and 4) the level of mortality that adult monarchs may be experiencing during the winter.

"Western Monarch Thanksgiving Count Data 1997-2020 shows that despite a strong volunteer effort, monarch numbers are at the lowest point recorded since the count started in 1997"

Western Monarch Population Closer to Extinction as the Wait Continues for Monarchs’ Protection Under the Endangered Species Act

During the 24th Western Monarch Thanksgiving Count, nearly 100 volunteers carefully surveyed groves of trees on the California and Northern Baja coast for monarch butterflies. Despite the challenges of conducting field work during a pandemic, volunteers surveyed 246 sites, three more than last year. Unfortunately, to the surprise and dismay of many, only 1,914 monarchs were counted at all the sites. This is a shocking 99.9% decline since the 1980s.

Plant trays containing thousands of seedlings are laid out on the ground.

Pollinator Conservation Program Digest – December 2020

This edition focuses on work done across the country to support monarch butterflies and other pollinators. Jessa Kay Cruz describes how Xerces supports groups in California undertaking habitat creation projects, and Jennifer Hopwood presents a series of fact sheets about milkweeds, part of a nationwide project to provide information to roadside managers.

Three young men use shovels to help plant a new tree in the middle of a grove

Planning and Planting for the Future of Monarchs in California

Pismo State Beach is one of the most important overwintering sites for monarchs in California. It has regularly hosted over 10% of the entire western monarch population each winter. Xerces Society has partnered with California State Parks, Creekside Center for Earth Observation, and others to develop and implement a plan to restore and enhance the site’s ability to host monarchs.

A handful of monarch butterflies with wings closed rest on the long gray-green leaves of eucalyptus

Monarch Population in California Spirals to Another Record Low

Early count numbers from Xerces’ Western Monarch Thanksgiving Count suggest that the western migratory population is headed for an all-time low. If early data reflects monitoring at the rest of the sites, we may see fewer than 10,000 monarchs overwintering in California this year.

An orange and black monarch butterfly drinks nectar from the creamy-white flowers of mule fat

Western Monarch Breeding Season Status

The western monarch breeding season is coming to a close for 2020 and we are in the midst of the fall migration—the time when monarch butterflies are making the long journey back to their overwintering grounds. Following two years during which the western monarch butterfly population hit the lowest levels ever recorded, researchers were looking for signs of a successful breeding season.

A man kneels beside a tray of wildflower seedlings, carefully removing each one in readiness for planting them.

Supporting Community Efforts to Create Monarch and Pollinator Habitat in California

Creating habitat in California is an essential step in recovering the monarch -- as well as to support the many other species of butterflies and bees in that state. Xerces worked with local native plant nurseries to create and distribute monarch and pollinator “habitat kits”, each with more than a thousand climate-smart, locally native plants -- enough to make a lasting impact for monarchs.

Pale pink flowers of narrow-leaf milkweed growing beside a tomato field in California's Central Valley.

Science Notes: How Pesticide Sampling Can Help Restore Imperiled Western Monarchs

California’s Central Valley is critical breeding habitat for migrating western monarchs. In partnership with the University of Nevada, Reno, Xerces scientists tested milkweeds growing in the valley for pesticides. Sixty-four different pesticides were found across the samples, with an average of nine pesticides per sample.

Monarchs stand close together on muddy ground on the edge of a puddle.

Monarchs Overwintering in Mexico Down 53%

This decline makes it clear that monarchs are not recovering and still urgently need Endangered Species Act protection in the United States and extraordinary conservation efforts throughout North America. Learn how to help here.

A monarch with large pieces missing from both wings perches on an evergreen branch.

New Year’s Count Finds Continued Decline of Monarchs Overwintering in California

Monitoring revealed an average decrease of 46% between the Thanksgiving and New Year’s counts. While the decline is alarming, the silver lining is that this data has provided a concrete list of priority sites to target for conservation efforts.

In this hand-drawn/hand-painted image, a grove of trees is shown, with a cut stump and a dead monarch with tattered wings in the foreground.

The Vanishing Butterfly Groves of California

The latest research suggests that the damage and loss of overwintering habitat is one of the primary drivers of the decline of western monarchs. Together, we can make overwintering site protection and management a reality.

A monarch clings to the trunk of a tree in a dimly-lit landscape.

Thanksgiving Count Shows Western Monarchs Need Our Help More than Ever

The western monarch population remains at a critical level. With some luck and a lot of hard work, we have hope that we can save this incredible migration.

In this close-up photo, a monarch perches atop a cluster of small, white and pink flowers. The image is so detailed, you can see the eye of the monarch, and the scales on its wings.

Monarch and Pollinator Habitat Kits Designed to Support Imperiled Western Monarchs

These specially designed kits, geared towards large-scale projects, incorporate native milkweeds, nectar plants, and climate considerations.

With wings spread, a monarch butterfly basks on a milkweed plant among the stems of a tulle marsh.

Western Monarchs: Notes from the Field

Staff from the Xerces Society and our partners have been keeping close eyes on the imperiled western monarch population at study sites in California, Nevada, Oregon, Washington, and Idaho as part of a multi-year collaborative research project.

Rugged mountains and pine trees, some reddish brown and some green, are shown in this Colorado landscape.

Pollinator Conservation Program Digest – September 2019

September’s featured staff members have been providing Monarch and Pollinator Habitat Kits to select organizations in California, training Colorado Department of Transportation staff on roadside pollinator habitat, and attending the America’s Grasslands Conference, held this year in North Dakota.

Two monarchs' wings overlap as they stand back end to back end, mating.

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