In December, 2002, a coalition of conservation organizations, including the Xerces Society, petitioned the U.S. Fish and Wildlife Service to have three butterfly species listed as Endangered under the Endangered Species Act. The species are Taylor’s checkerspot, Mardon skipper and island marble.
These species are threatened by the loss of their native grassland habitat from causes such as agricultural and urban development, encroachment of trees, and spread of invasive plants. More than 90% of Puget Sound prairies, grasslands and oak woodlands have been destroyed; only three percent remain in relatively good health. Mace Vaughan, staff entomologist at the Xerces Society says, “If something isn’t done soon to protect what remains of its unique grassland habitat, we likely will lose the Taylor’s checkerspot in the next couple of years.” Pesticide use, recreational activities and grazing pose additional threats to the butterflies.
Scott Hoffman Black, Executive Director of the Xerces Society commented, “Butterflies are important environmental monitors. They are like the canary in the coal mine and show, once again, that these grassland ecosystems, and all of the species that depend on them, are in trouble.”
The butterflies all inhabit native prairie in the Puget Sound area. Only four populations of the Taylor’s or Whulge checkerspot (Euphydryas editha taylori) remain and three contain fewer than fifty individuals, based on surveys conducted in 2002. It formerly occupied extensive grasslands, prairies and oak woodlands in the Puget Sound Basin, on Vancouver Island and in the Willamette Valley.
The island marble (Euchloe ausonides insulana) is found in only one place on San Juan Island. It formerly occurred on southern Vancouver Island, the Gulf islands and other islands in the San Juan group. It had been believed to be extinct since the 1920’s, but was rediscovered in 1998 on San Juan Island.
Marden skippers (Polites mardon) occupies a wider area than the other two butterflies. The Marden once occupied extensive fescue grasslands in Washington, Oregon and northern California, but it has recently been extirpated from four sites in south Puget Sound. Just four small, geographically-isolated populations remain in south Puget Sound, the Cascade Mountains in southern Washington, the Siskiyou Mountains in southern Oregon, and coastal northern California. All of the sites are small, and most of them support fewer than 50 individuals.
Petitions were also filed for the streaked horned lark and eight species of pocket gopher that are associated with grasslands, prairies and oak woodlands of the Puget Sound Basin and Willamette Valley.
The source of information for this article is Xerces Society homepage at www.xerces.org. The site has more information about the butterflies, including photographs.
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