One of Nation’s Rarest Butterflies Closer to Protection under the Endangered Species Act


The Xerces Society for Invertebrate Conservation:
Scott Hoffman Black, Executive Director, (503) 449-3792, [email protected];
Sarina Jepsen, Endangered Species Program Director, (971) 244-3727, [email protected]

One of Nation’s Rarest Butterflies Closer to Protection under the Endangered Species Act

The island marble butterfly needs protection to avoid extinction

OLYMPIA, Wash.—Responding to a petition from the Xerces Society for Invertebrate Conservation, the U.S. Fish and Wildlife Service (USFWS) has issued a positive 90-day finding for the island marble butterfly, to be published in the Federal Register on Tuesday, August 19, determining that protection may be warranted and initiating a status review of the species. This action resulted from a settlement agreement between the Xerces Society and USFWS.

The island marble is among the most imperiled animals in the world because it has an extremely small and isolated population, has experienced recent declines in abundance and site occupancy and because its habitat faces continued threats. After an extensive status review, the Xerces Society concluded that this narrowly endemic butterfly is in imminent danger of extinction.

“We are happy that the U.S. Fish and Wildlife Service has taken this positive step toward protection of this butterfly,” said Scott Hoffman Black, Executive Director of the Xerces Society. “After years of delay, the Service must move quickly to complete a 12-month status review and ensure that the butterfly gets the protection it deserves.”

This green and white butterfly has already been extirpated from Canada, and now is known to inhabit open grasslands on only two small islands (San Juan and Lopez) in northwest Washington state. A decade of survey work has found that the island marble continues to lose habitat each year and the vast majority of sites at which it was recorded no longer support it. As of 2011, the island marble continued to persist at just six of 12 previously occupied sites within San Juan Island National Historic Park, and just two of 40 previously occupied sites outside of the park.

“Fewer and fewer butterflies are being seen, and even well-established sites have recently been lost,” said Sarah Foltz Jordan, Conservation Biologist with the Xerces Society and lead author of the petition. “These sudden declines underscore the urgency of the situation, and the necessity of Endangered Species Act protection for this animal.”

The continued survival of the island marble is threatened by a wide range of factors, including consumption of its host plants by deer and other animals, mowing and removal of host plants, agricultural practices that are not compatible with the butterfly, herbicide use, improperly timed management practices, predicted rise in sea level and increased storm surges due to climate change, and other natural and anthropogenic threats.

Although the USFWS issued a negative 12-month finding in 2006 following a previous listing petition submitted by the Xerces Society and partners, a substantial amount of new research presented in the petition demonstrates that this butterfly meets the criteria of an Endangered Species under the Endangered Species Act.

Listing the island marble butterfly under the Endangered Species Act would help protect this butterfly from harm and ensure that all projects requiring a federal permit within its habitat first consider the needs of the butterfly.

“The island marble’s extremely small population size, isolation and restricted distribution place a huge question mark over its survival,” said Sarina Jepsen, Endangered Species Program Director with the Xerces Society. “Endangered Species Act protection is this butterfly’s only real hope.”

The Xerces Society is represented by Chris Winter of the Crag Law Center, a public interest environmental law firm based out of Portland, Oregon.


For more information about the island marble butterfly visit:

To read the complete Endangered Species Act petition submitted to the U.S. Fish and Wildlife Service visit:

To read the announcement to be published in the Federal Register [Docket No. FWS-R1-ES-2014-0025; 4500030113; Filed: 08/18/14 at 8:45 am; Publication Date: 8/19/2014]: