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Feds Seeking Endangered Species Protection For Rare Island Marble Butterfly

Federal wildlife officials want to protect a rare green-and-white butterfly that is only found on San Juan Island by listing it as an endangered species.

The tiny creature has been declining since it was rediscovered twenty years ago. Its population is now estimated at fewer than 200 in the wild.

The proposed listing seeks to keep the species from going extinct.

The island marble butterfly has a 1.75-inch wingspan with bright green and white speckles on the underside. It flies quickly over short distances and prefers to lay its eggs on just three species of native mustard and peppergrass plants.

Its known range has shrunk to about 813 acres, all of it on San Juan Island. That land would also be listed as critical habitat under the new designation. Most of it is public property at American Camp in San Juan Island National Historic Park.

“This is a precious organism that you will see nowhere else on the planet,” says Karen Reagan, an endangered species biologist with the U.S. Fish and Wildlife Service in Lacey.  

She says the new listing would ensure the highest protection available for any species under federal law.

“No collecting, no hurting it, no harming it, no chasing it, no harassing it,” Reagan says.

And there will likely be more funding to for things like fencing to keep deer from accidentally eating the butterfly’s larvae or to keep people from accidently trampling the chrysalises, which can be tucked nearly invisibly into underbrush for as much as 330 days of the year.

Additional money could fund more captive breeding and more habitat restoration work or incentives for landowners to create habitat that scientists hope will boost the butterfly’s numbers.

Already A Candidate For ESA Listing

Two years ago, the species qualified for protection, but only as a candidate, which meant other species were prioritized and no funding was provided.

Funding for this work is the key, says Scott Black, a conservation biologist and Executive Director of the Xerces Society, which has been petitioning for this highest level of federal protection for the island marble butterfly for more than 15 years.

“It really needs to happen. We need to really step up conservation efforts. And I think this listing will help to do that,” Black said.

He says it’s exciting but also a little bittersweet to see it finally happening now, knowing that if they had started a decade or more ago, when there were still established populations of the butterfly on Lopez Island, there would have been more opportunities for success. Now, he says, they are truly facing an imperiled status so dire you could compare it to being in a hospital emergency room.

“This butterfly may still go extinct, no matter what we do. But we believe there are some conservation actions that we can do to hopefully reverse its decline,” he says. 

He says species like this one, even in tiny numbers at the base of the food chain, need to be preserved as part of overall efforts to protect a functioning planet for all life on earth.

“If we can protect all of the animals and the places that they live – or as many as possible – we’re protecting the planet for us,” Black says.

The proposed listing isopen for public comment for two months. It’s expected to become law in April 2019.

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to