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Petition filed to add Island Marble Butterfly to Endangered Species List

210-im-butterflyThe Xerces Society for Invertebrate Conservation filed a petition today, August 22, 2012 requesting that the U.S. Fish and Wildlife Service extend Endangered Species Act protection to the island marble butterfly.

The butterfly, found on Lopez and San Juan islands only, is in imminent danger of extinction.


Because it has an extremely small and isolated population, has experienced recent declines in abundance and site occupancy, and its habitat faces continued threats, it is among the most imperiled animals in the world according to Xerces Society.


This green and white butterfly has already been extirpated from Canada, and now is known to inhabit open grasslands. 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: herbicide use, mowing, and other improperly-timed management practices; grazing of the butterfly's host plants by deer, introduced rabbits, and livestock (cattle and sheep); climate change; and the loss of its prairie habitats due to succession to forest and invasive species.

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.

island-butterfly-xeresListing 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 ESA also makes it illegal to possess, sell, or transport any listed species taken in violation of the law. For plants, trade restrictions arethe same but the rules on "take" are different. States have more restrictive laws specifically prohibiting the take of State or federally listed plants and animals.

"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 More information about the island marble.

ABOUT THE XERCES SOCIETY 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. 

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