San Juan Island pushes to save near-extinct butterflies

San Juan Island works to save one of the rarest butterflies in North America

The Island Marble Butterfly was thought to be extinct for almost 100 years, but in 1998 it was re-discovered during a prairie survey at American Camp in San Juan Island National Historical Park.

SAN JUAN ISLAND, Wash. - San Juan Island in Washington state is the last bastion of hope for one of the rarest butterflies in North America: the Island Marble Butterfly.

This rare pollinator was thought to be extinct for almost 100 years, but in 1998 it was re-discovered during a prairie survey at American Camp in San Juan Island National Historical Park.

Specimens of the butterfly had also been previously found in Lopez Island, Vancouver Island and Gabriola Island in British Columbia. Today, they are thought to only exist in San Juan Island.

Sara Dolan with the National Park Service explains that while the butterfly re-emerged from obscurity in the late 1990s, only 300-500 are estimated to exist today.

"It’s really right on the brink of extinction," Dolan said.

The Island Marble Butterfly is a white butterfly with yellow and green marbling. It lives most of its life on specific host plants. One of the leading threats to it is thought to be its loss of habitat.

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Island Marble Butterfly

In 2013, San Juan Island National Historical Park started a captive rearing program. Park biologist Claire Crawbuck explains that these efforts have roots that precede the park’s program.

"There were captive rearings of the butterfly before that and that was led by local ecologist Susan Vernon," Crawbuck said. "She collected eggs and larva from that area that she knew was being threatened and brought them to her home to capture and rear them. And she learned techniques on how to best serve the species and taught those to the park."

Crawbuck explains that the survival rate for the butterfly is 4% to 5% in the wild, much lower than the 85% survival rate at the captive rearing facility operated today by On Sacred Ground.

A parallel approach being used is the creation of new habitat for the butterfly. The San Juan Island Conservation District is a private organization that guides the development of habitat on land owned by residents of San Juan Island that volunteer.

"We are basically gardening. It’s wild gardening," said Sam Martin from Ecostudies Institute.

Martin explains that these habitat plots are protected with fencing, so they are not eaten by deer.

Field mustard is one of the plants capable of hosting the Island Marble Butterfly, and it is already doing that inside the habitat plot next to the Cattle Point Lighthouse.

"There are actually Island Marble Butterfly eggs and maybe larva here, now for the first time." Martin pointed out as she examined the yellow flowers of the Field Mustard.

While the future of the butterfly remains uncertain, it has become a symbol of hope and community for many islanders.

"The path forward is being forged right now because we have all these people making habitat and then those steppingstones will interconnect to try to have the butterfly go beyond the park service lands as the core population and establish other core populations. The goal eventually is to translocate the butterfly to Lopez Island and beyond," Dolan said.