12-month finding on a petition to list the island marble butterfly

Submitted by National Park Service

​The U.S. ​Fish and Wildlife Service has determined that the island marble butterfly (Euchloe ausonides insulanus) is warranted for listing under the Endangered Species Act, but precluded by higher priority listing actions.

The island marble butterfly will be added to the service’s candidate species list. These are species for which the service has enough information regarding their biological status and threats to propose them as threatened or endangered, but listing is currently precluded by higher priority listing activities.

“Conservation of the island marble butterfly remains a significant concern for the service,” said Washington State Supervisor Eric Rickerson. “We will continue to closely monitor the butterfly and work with our partners to implement conservation measures and address threats to the species.”

The island marble butterfly is a species only found in the San Juan archipelago in San Juan County, Washington. The only remaining known population is centered on American Camp, a part of San Juan Island National Historical Park on San Juan Island. Threats to the species include: habitat loss, direct and incidental predation, and small population size. Small population size renders the species vulnerable to additional random events, such as severe weather events, storm surges that destroy habitat, or any other event that increases mortality.

The service has been actively working with federal, state, county and non-governmental organization partners, San Juan County Land Bank, San Juan Preservation Trust, Friends of the San Juans, San Juan County Parks, and local landowners since 2006 to implement voluntary conservation actions to ensure protection and conservation of the island marble butterfly. Despite ongoing conservation efforts, these endeavors are currently insufficient to improve the status of the island marble butterfly or fully address current and future threats to the species.

The service will continue to actively work with partners to implement ongoing actions as well as develop new conservation actions to protect and conserve the island marble butterfly. The status of all species on the candidate list are reviewed and updated annually in the Candidate Notice of Review, available at www.fws.govendangered/what-.

To read the federal register notice, or for more information about management activities and conservation of the island marble butterfly visit www.fws.gov/wafwo.

The U.S. Fish and Wildlife Service works with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. For more information, visit www.fws.gov/pacific, or connect with us through facebook.com/USFWSPacific,, tumblr.com/blog/usfwspacific, flickr.com/photos/ andyoutube.com/user/USFWS.