The Xerces blue butterfly that used to flutter across SF’s western dunes went extinct 80 years ago, but wildlife experts have identified the closest known relatives of that butterfly, and they just reintroduced a bunch of them in the Presidio.
You may remember a sort of Earth Day prank two years ago when someone put a rogue, unauthorized butterfly statue where the Junipero Serra statue had been torn down during the George Floyd protests.
The SF Arts Commission had the butterfly statue taken down, along with its makeshift plaque reading “Memorial to the extinct Xerces blue butterfly. Driven to extinction by urban development and the destruction of sand dunes of the San Francisco peninsula, the Xerces blue was last seen in the Presidio on March 23, 1943.”
And it is true that the development of the west side of town wiped out these butterflies’ habitat and caused their extinction, and the Xerces blue would be the first butterfly species to go extinct in North America.
But last year, KGO reported that wildlife experts were sequencing the genome of the extinct Xerces blue butterfly in order to find the closest possible genetic relative, in hopes of replacing the butterfly. They discovered that relative was a species called the Silvery blue butterfly. And now the Chronicle informs us that seven Silvery blue butterflies were released in the Presidio on Tuesday, in an effort to restore native species to that park.
“This isn’t a Jurassic Park-style de-extinction project, but it will have a major impact. The Silvery blue will act as an ecological ‘stand-in’ for the Xerces blue, performing the same ecosystem functions as both a pollinator and a critical member of the food web,” California Academy of Sciences lead researcher Dr. Durrell Kapan said in a press release. “To ensure a successful reintroduction, we needed to identify a subpopulation that shared genetic and ecological similarities with the Xerces blue: a sand dune specialist that is well-adapted to the cool, foggy climate of San Francisco and relies on the same host plant, deerweed."
According to the Chronicle, while seven of the new butterflies were released in the Presidio this week, 27 were introduced last week. And they are expected to start laying eggs quickly. This is important, because part of this “restoring of the ecosystem” is that some of these butterflies will serve as food for lizards and birds.
And as the Chronicle notes, after the butterflies were released, Dr. Kapan “added, under his breath, ‘Super happy we didn't see a swallow.’”
Image: Gayle Laird, California Academy of Sciences
