Conserving the Nature of America

News Release

Critical Habitat Proposed for Bay Checkerspot Butterfly

August 22, 2007


Division of Public Affairs
External Affairs
Telephone: 703-358-2220

The U.S. Fish and Wildlife Service today published a proposed 19,746-acre critical habitat in Santa Clara and San Mateo counties for the threatened Bay checkerspot, a colorful butterfly that occurs only on small patches of inhospitable soil where its limited food supply grows.

The proposal is 4,000 acres smaller than a 2001 critical habitat rule that later was sent back to the Service by a lawsuit. Today's announcement opens a 60-day public comment period on the new proposal, which is timed to meet a court deadline of Aug. 14, 2008 for a final determination. Ninety per cent of the proposal critical habitat is in Santa Clara County; over half in one large unit just east of the Coyote Valley.

The Service believes that cooperative conservation efforts involving many interests is the key to recovering the species, more than critical habitat, which adds little protection. Re-introduction of the Bay checkerspot to Edgewood Park last spring by a large group of interested local residents shows how the species is likely to recover, according to the Service. Edgewood Park is one of the proposed critical habitat units.

The butterfly is recognized by its distinctive markings on its 2-inch wingspan. All its wing veins have black bands that encompass bright orange, red and white spots. It lives in areas with serpentine soils, a harsh environment lacking many plant nutrients. This naturally limits the butterfly's original range to 12,000 acres that support the butterfly's only larval foods, dwarf plantain and purple owl's clover.

Historically, the Bay checkerspot occurred primarily along the spine of the San Francisco peninsula, from Twin Peaks to southern Santa Clara County and in a few pockets in Alameda and Contra Costa counties. However, habitat loss and fragmentation, extreme weather, air pollution, pesticides, vehicle strikes, fire, overgrazing, gopher control, illegal collecting, and invasion of exotic species have greatly reduced the butterfly's numbers.

Critical habitat is a term in the Endangered Species Act (ESA) that identifies geographic areas containing features essential for the conservation of a threatened or endangered species and that may require special management considerations or protection.

The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve or other conservation area. Federal agencies that undertake, fund or permit activities that may affect critical habitat are required to consult with the Fish and Wildlife Service to ensure such actions do not adversely modify or destroy designated critical habitat. The designation does not affect purely private or state actions on private or state lands, nor require non-federal lands to be positively managed for conservation.

Comments on the proposed critical habitat may be submitted until Oct. 20, 2007. Comments may be directed by email to:, or by mail to: Field Supervisor, Sacramento Fish and Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, CA 95825. A copy of the proposed critical habitat, along with other information about the Bay checkerspot is available on the Internet at

The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 97-million-acre National Wildlife Refuge System, which encompasses 547 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 64 fishery resources offices and 81 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign and Native American tribal governments with their conservation efforts. It also oversees the Federal Assistance program, which distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.


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