Pacific Southwest Region
California, Nevada and Klamath Basin

Protection of the Mt. Charleston Blue Butterfly under Endangered Species Act

Mar 07, 2011

For Immediate Release:
March 7, 2011   

Contact:  Dan Balduini,  (702) 515-5480

Protection of the Mt. Charleston Blue Butterfly under Endangered Species Act
Is Warranted but Precluded

LAS VEGAS - The U.S. Fish and Wildlife Service (Service) has determined that the Mt. Charleston blue butterfly (Plebejus shasta charlestonensis) (formerly in the genus Icaricia) warrants protection under the Endangered Species Act, but that adding the subspecies to the Federal Lists of Endangered and Threatened Wildlife and Plants is precluded by the need to complete other listing actions of a higher priority.  The Service’s decision will be published in the Federal Register on Tuesday, March 8, 2011.

In making this determination, the Service completed a comprehensive review, known as a 12-month finding, and found that the best scientific and commercial data available indicates the Mt. Charleston blue butterfly is warranted for listing as a threatened or endangered species throughout its range.  However, the Service is precluded from beginning work immediately on a listing proposal because its limited resources must be devoted to other, higher priority actions.  The Mt. Charleston blue butterfly will be added to the list of candidate species eligible for Endangered Species Act protection.  The Service will continue to work closely with the U.S. Forest Service and other entities to promote cooperative conservation efforts including surveys, life history studies, habitat protection, and restoration activities.

“Some butterflies were observed during surveys conducted in July and August of 2010, yet the population appears to be extremely low,” said Jill Ralston, Deputy State Supervisor for the Service’s Nevada Fish and Wildlife Office in Reno.  “Additional surveys are planned for 2011 in Upper Kyle and Lee Canyons to monitor population trends and distribution of the Mt. Charleston blue.” 

The Mt. Charleston blue butterfly is a subspecies of the wider-ranging Shasta blue butterfly (Plebejus shasta).  The Service assigned the Mt. Charleston blue butterfly a Listing Priority Number of 3, which is the highest-priority rank possible for a subspecies under the Service’s current guidance for adding species to the Lists of Endangered and Threatened Wildlife and Plants.  The Service will prepare a proposed rule to list the Mt. Charleston blue as soon as possible given higher-priority listing actions, court orders, and court-approved settlement agreements with specific deadlines.

The Service retains the option to list the butterfly on an emergency basis, and will continue to coordinate efforts with the Forest Service to reduce existing threats and ensure new ones do not occur.

The Mt. Charleston blue butterfly is highly vulnerable to threats because of its small population size and limited distribution.  Threats contributing to its decline that were identified in the 12-month finding include: (1) The loss and degradation of habitat due to fire suppression and succession, implementation of recreation development projects and fuels reduction projects, and increases in nonnative plants; (2) inadequate regulatory mechanisms; and (3) extreme precipitation events and drought, which are likely to become more frequent under climate change.  Because of these threats, the Service determined the Mt. Charleston blue butterfly should be listed as threatened or endangered throughout its entire range.

Given the decline in population of the Mt. Charleston blue butterfly over the last 15 years, active and sustained conservation of the butterfly and its habitat is required.  This species, along with other wildlife and plants endemic to the Spring Mountains, was included in the 1998 Conservation Agreement for the Spring Mountains National Recreation Area and was incorporated into the Clark County Multiple Species Habitat Conservation Plan in 2000.

The finding is available on the Internet at (Docket Number FWS-R8-ES-2010-0028) and at  Supporting documents used in preparing this finding are available for inspection by appointment, during normal business hours at the Nevada Fish and Wildlife Office in Las Vegas at 4701 North Torrey Pines Drive, telephone 702/515-5230, facsimile 702/515-5231.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people.  We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals and commitment to public service.  For more information on our work and the people who make it happen, visit


NOTE: Photos of the Mt. Charleston blue butterfly are available on Flickr at: