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Xerces Blog

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.

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.

Surveys of monarch butterflies overwintering in central Mexico by World Wildlife Fund–Mexico found that the butterflies occupied an estimated 2.1 hectares of forest during the winter of 2020–21, approximately 26% less than the previous winter. Scientists estimate that 6 hectares are necessary to sustain the population.

Our pollinator team members provide regular digests on their work. In this bumper edition, three of our staff provide updates. Stephanie Frischie discusses planting seeds, Nancy Lee Adamson highlights monarch conservation in the Southeast, and Emily May introduces a newly released video.

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.

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.

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.

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.

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.

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.

Ink Dwell studio launched the Migrating Mural project in 2012 to celebrate animals that migrate, creating impossible-to-ignore artworks as monuments to the wonders of the natural world.

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.

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.

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.

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.

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

Together, these publications contribute to our growing understanding of how human actions can hurt—or help—monarchs.

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.

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.

These new regulations will make it much harder to protect and recover the animals that are struggling to survive and need our help the most.

Western monarch researchers and community scientists have been busy, contributing information vital to understanding the situation facing this imperiled population.

The Xerces Society is working across the U.S. to conserve this beloved species, and there are a number of ways you can help!

We need all hands on deck this season, to better understand the hurdles facing the imperiled western monarch population!

Helping the monarch back to full health isn’t going to be easy or quick, but together we can transform the landscape to allow the monarch to rebound—and give our children the gift of watching orange wings flap in the sunshine.

The Xerces Society is happy to announce the 2019 DeWind awardees: Niranjana Krishnan, a PhD candidate at Iowa State University, and Molly Wiebush, a master’s student at Florida State University.

While hiking in California and the rest of the West, you can help researchers by submitting any and all monarch and milkweed observations this year to the Western Monarch Milkweed Mapper website.

Xerces Society Endangered Species Conservation Biologist and Western Monarch Lead Emma Pelton recounts her recent experience in Mexico with this photo essay.

Overall, the count data revealed an average decrease of 38% between the Thanksgiving and New Year’s counts.

We urge you to join us and our colleagues in the western monarch science and conservation community in taking meaningful, swift action to help save western monarchs.

The California overwintering population has been reduced to less than 0.5% of its historical size, and has declined by 86% compared to 2017.

What can you do to help the monarch? Protect habitat, avoid pesticide use, plant gardens, and contribute data to Xerces-led community science efforts.

Oklahoma’s impressive butterfly fauna of more than 170 species includes the nation’s largest and the smallest, and representatives of all six major butterfly families.

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.

Remembering a ground-breaking monarch researcher, a passionate advocate for monarchs, and a beloved member of the conservation community.

A new guide to protecting the monarch butterfly from the Pacific to the Rockies presents a holistic approach to monarch conservation.

Here are some ways you can work to promote a healthy planet for invertebrates and the people they let share their planet.

Milkweed is in demand, and that demand has been filled in recent years by tropical milkweed, a non-native species. But is planting tropical milkweed potentially doing more harm than good?

The Xerces Society's Western Monarch Thanksgiving Count provides a long-running record of the number of monarchs overwintering in California-including the steep decline of recent decades.

This western monarch butterfly overwintering site management plan also serves as a template for land managers at other overwintering sites.

Unusual fall weather may have contributed to the lowest overwintering western monarch population recorded since 2012.

Harvesting local milkweed seed for later planting is a great way to increase monarch breeding habitat. We'll teach you how to harvest and separate the fluff from the good stuff.

A new study from the USGS, Univ. of Arizona, and partner organizations finds 1.3 additional milkweed stems are needed in the Midwestern U.S. to recover monarch butterfly populations.

A documented 74% decline in the California overwintering population since the late 1990s mirrors the steep decline, estimated at 80–90%, of the number of butterflies in Michoacán over the same period.

For 40 years, the monarch migration phenomena has been recognized as a conservation priority.

Adult monarchs need nectar to fuel them during spring migration and breeding and to build up stores of fat which sustain them during fall migration and winter.

While you may be familiar with the impressive monarch clusters, family-friendly amenities, and helpful docents at Pismo Beach, Pacific Grove, Natural Bridges, and Ardenwood Historic Farm, there are many more places monarchs overwinter along the coast.

Much of the focus on monarch butterflies is on the eastern population. Monarchs in western North America are in greater decline and need conservation help.