Extinct butterfly at San Francisco Presidio being replaced with close relative
By Itay Hod
On a cool April morning in the Presidio, a team of volunteers fans out across the dunes, cameras in hand, and lenses ready. At first glance, it looks like they’ve come to capture something. But on this particular day, they were here to set something free.
For the past three years, Durrell Kapan, a senior research fellow at the California Academy of Sciences, has been trying to right what he calls an 80-year-old wrong.
“The Xerces blue is sort of a black spot on our record,” he said.
The story began in the late 19th century, when San Francisco paved over its coastal dunes for development, taking with it a tiny, iridescent butterfly known as the Xerces blue. By the early 1940s, it was gone, widely recognized as the first butterfly in North America driven to extinction by human activity.
Decades later, conservationists brought the dunes back, the sand, the native plants, and the ecosystem. But not the butterfly. So, Kapan and his team turned to the Xerces Blue’s closest living relative: the silvery blue butterfly.
Collected near Big Sur, the butterflies have been transported north and released under small mesh enclosures placed over deerweed, their host plant. The idea is simple: let them discover the habitat before they have a chance to leave it.
Restoring habitats isn’t new. But using one species to stand in for another, hoping it can fill the same ecological role, is a more unusual approach.
“Butterflies are an important part of the ecosystem,” says Phoebe Parker-Shames, a wildlife ecologist with the Presidio Trust.
And there are early signs it’s working. Researchers have already spotted unmarked Silvery Blues, an indication that some are being born here, not just brought in. So far, 46 butterflies have been released at the Presidio this spring, 167 in total.
“That’s the proof of all these little improbable pieces coming together,” Parker-Shames said.
By the end of the day, 14 more butterflies have a new home. For Kapan, the work is about more than restoration.
“By changing this, we’re learning how to repair nature,” he said.
