Island Marble Butterfly on the Brink of Extinction 
Scientists Act to Protect one of America's Most Endangered Animals 

For immediate release: August 22, 2012



Scott Hoffman Black, Executive Director, Xerces Society for Invertebrate Conservation; 503-449-3792;


Portland, Ore. -- TheXerces Society for Invertebrate Conservation filed a petition today requesting that the U.S. Fish and Wildlife Service extend Endangered Species Act protection to the island marble butterfly.


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.


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 island marble, 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 ESA.


Listing the island marble 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 marbles' 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."


Read the complete petition
For more information about the island marble, visit 

The Xerces Society is a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat. Established in 1971, the Society is at the forefront of invertebrate protection worldwide, harnessing the knowledge of scientists and the enthusiasm of citizens to implement conservation programs. To learn more about our work or to donate to the Society, please visit
Island marble butterfly (Euchloe ausonides insulanus) by Robert M. Pyle. 
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