PORTLAND, Ore.; November 9, 2017 – The image of monarch butterflies winging their way for hundreds or thousands of miles to find winter shelter enthralls children and adults alike. To support this annual cycle, monarchs need milkweed and nectar, but also secure overwintering sites, the target of their epic flight. These sites are increasingly under threat. The just-released Protecting California’s Butterfly Groves will help site managers in the state care for this precious resource.

Scattered along the California coast are groves of eucalyptus, cypress, and pine which provide winter shelter to hundreds of thousands of monarch butterflies born each summer across the western North America.

“While this may sound like a lot of butterflies,” said Emma Pelton, conservation biologist for the Xerces Society, “in the 1980s, they numbered in the millions. The population has declined by over 95% in the last thirty years, and the migratory monarch population is now at a high risk of extinction.”

Having so many butterflies concentrated in such small areas means monarchs are especially vulnerable during the winter. Being concentrated along the coast makes the butterflies susceptible to storms and disturbance.

In addition, dozens of coastal overwintering sites have already been lost due to urban, ex-urban, and—to a lesser extent—agricultural development over the past decades. Others are senescing as drought and age take their toll.

“Without suitable places to overwinter, the monarch migration may collapse,” noted Sarina Jepsen, director of the endangered species program at the Xerces Society. “Protection and management of existing sites is crucial to prevent further loss of butterflies.”

To guide land managers, landowners, and community groups care for these sites and maintain the conditions that monarchs require, the Xerces Society partnered with Stu Weiss of Creekside Center for Earth Observation to publish Protecting California’s Butterfly Groves: Management Guidelines for Monarch Butterfly Overwintering Habitat.

These guidelines will help site managers become familiar with overwintering monarch habitat needs and provides a roadmap to develop site-specific management plans to benefit monarchs in both the short- and long-term.

“Ensuring sufficient, high-quality overwintering habitat is essential if we hope to recover the western monarch population,” said Jepsen.

The Xerces Society is a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat. Established in 1971, the Society is a trusted source for science-based information and advice. We collaborate with people and institutions at all levels to protect invertebrates in all landscapes. Our team draws together experts from the fields of habitat restoration, entomology, botany, and conservation biology with a single focus—protecting the life that sustains us. To learn more about our work, please visit www.xerces.org.

Download a copy of Protecting California’s Butterfly Groves: Management Guidelines for Monarch Butterfly Overwintering Habitat at https://xerces.org/protecting-californias-butterfly-groves/

For more information about the monarch population that migrates to California:

Schultz, C. B., L. M. Brown, E. Pelton, and E. E. Crone. 2017. Citizen science monitoring demonstrates dramatic declines of monarch butterflies in western North America. Biological Conservation.

For more information about the condition of monarch groves in California:

State of the Monarch Butterfly Overwintering Sites in California (2016)