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Presidio Trust Ecologists Launch “Operation Checkerspot"


Wildlife ecologists from the Presidio Trust, along with various local experts, seek to re-establish Euphydryas chalcedona, commonly referred to as the Variable checkerspot or the Chalcedon checkerspot, in the Presidio of San Francisco at El Polin Spring and Presidio Hills. This will be the sixth native wildlife species to be re-introduced at the Presidio since such ecological restoration efforts began in 1994, further enhancing the natural ecosystem of the park and of San Francisco itself.

E. chalcedona is a common species of butterfly ranging across the Western States of North America and along the West Coast, extending from Baja California to Alaska. While the checkerspot was once prevalent in the City and County of San Francisco, it is now isolated to one remnant population at Laguna Honda Reservoir. The primary cause of its decline in the city was habitat loss and the associated decline of larval host plants, the sticky monkey-flower (Mimulus aurantiacus) and bee plant (Scrophularia californica).

Says Jonathan Young, Wildlife Ecologist with the Presidio Trust: “The Presidio once again contains prime habitat capable of sustaining a long-term healthy population of the checkerspot butterfly and we expect its re-introduction to be a success. The biggest opportunity behind this project is public outreach and education about the plight of biodiversity and what it means to bring back a lost species. It is my hope that this project will spark people’s imagination, curiosity, wonder, and respect for the natural world.”

The species historically occurred in the Presidio and was last recorded in September of 1978. Since the park’s inauguration in the mid-1990s, approximately 50 acres of suitable and contiguous habitat has been restored and the butterfly’s host plant populations have dramatically increased, including two additional host plants commonly used in egg laying: the Indian paint brush (Castalleja spp.) and English plantain (Plantago lanceolate).

Young and his team will collect approximately 1500 larvae (caterpillars) between the months of March and April from a robust population at San Bruno Mountain, approximately seven miles south of the Presidio. They will be held at low temperatures during translocation, and then released on host plants at predetermined sites. Monitoring later in the year over the course of the adult flight season (April-June) will be accomplished through a volunteer-based citizen science program.

The Presidio Trust is committed to collecting and translocating larvae for a minimum of three years, hoping to establish self-sustaining populations within that time. The Trust is working with the assistance of San Mateo County Rec and Park, CA Fish and Wildlife, and experts Dr. John Hafernik, Dr. Stuart Weiss, and Liam O’Brien. Previous wildlife species introduced at the Presidio include the damselfly, chorus frog, western pond turtles, three-spine stickleback fish, and California floater mussels.

About the Presidio Trust

The Presidio Trust, a federal agency, is an innovation in the management of a treasured American place. The Trust was created to save the Presidio and transform it for a new national purpose. The Trust’s vision is that the Presidio will be forever a public place: vital to the Bay Area, important to all Americans, and recognized for achieving broad benefits for the nation. Today, the Presidio welcomes visitors, is home to a vibrant community of residents and tenants, and inspires greater good through programs that draw on its history and natural resources. The Presidio Trust serves the public with hundreds of free events, educational programs, and miles of trails and natural open spaces. To learn more, visit

Contact Us

Presidio Trust Media Relations

Lisa Petrie

(415) 264-7787

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