California Ringlets Get Helping Hand Returning to Presidio Grasslands

As of May 27, Presidio managers and local lepidopterists have moved 100 individuals, their target for this year’s first flight season. The butterflies appear to be happily taking to their new home. Presidio staff have even seen some of them mating! Jonathan Young / Presidio of San Francisco

May 2021 - The California ringlet (Coenonympha tullia california) was last seen in San Francisco’s Presidio in 2007. Grassland habitat loss and degradation from before the Presidio became a park contributed to its extirpation. Now, after more than two decades of grassland restoration, the time is ripe for this lost butterfly to return.

But the California ringlets can't return on their own. They are about the size of a quarter, and they're weak flyers. The nearest population may be a short distance away for a person, yet it's impossibly far if you're a California ringlet. So this spring, the butterflies have been getting a helping hand.

Presidio managers and local lepidopterists began reintroductions in April. They've been collecting ringlets just north of the Golden Gate, in Golden Gate National Recreation Area's Marin Headlands. In particular, they're collecting at Muir Beach South. There the ringlets are very abundant and well adapted to the foggy, coastal climate. "Team Ringlet" is aiming to collect roughly 200 butterflies per year for the next three years, spread across each year's two flight seasons/generations. They're also targeting a specific sex ratio of 2:1 females to males. The females, which each carry a dozen or so eggs, are most important for establishing a new generation. As of May 27, the team has moved 100 individuals, their target for this year’s first flight season. The butterflies appear to be happily taking to their new home. Presidio staff have even seen some of them mating!

Such early signs of success are definitely a thrill. But it may also be heartening to know that this is part of something bigger than the return of one butterfly. Reintroductions are improving biodiversity in the Presidio’s grasslands. More biodiversity helps reestablish complex plant and animal relationships. Ultimately, this means a more robust and resilient grassland community. The hope is that, even in the face of challenges like climate change, the grasslands can remain full of life.

For more information

• Check out a short video of a released butterfly and links to media coverage from the Presidio's blog
• Contact Presidio Wildlife Ecologist Jonathan Young

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Where this belongs

• Golden Gate National Recreation Area
• Presidio of San Francisco

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