Periodic Status Review for Taylor's Checkerspot (2016)

The Taylor's Checkerspot, a Pacific Northwest endemic butterfly, was historically found in grassland habitats from southeastern Vancouver Island, British Columbia, south through the Puget Trough in western Washington, and into the southern Willamette Valley in Oregon. Its distribution included 45 documented locations in Washington from the San Juan Islands south to the Cowlitz River in Lewis County. Today, the butterfly is restricted to 11 known populations: eight in Washington, one in British Columbia, and two in Oregon. Current distribution within Washington is greatly reduced from historical and limited to two geographically isolated areas; the south Puget Sound region (Pierce County), and the northeastern Olympic Peninsula (eastern Clallam County). In addition to the eight naturally occurring populations, efforts to reintroduce the butterfly are underway at four sites in the south Puget Sound region. Taylor's Checkerspot was listed as an endangered species by the Washington State Fish and Wildlife Commission in 2006, the Committee on the Status of Endangered Wildlife in Canada in 2011, and the U.S. Fish and Wildlife Service in 2013.

When listed endangered by the Washington Fish and Wildlife Commission in 2006, Taylor's Checkerspot was known to occur on 10 Washington sites in Clallam, Pierce, and Thurston counties. In the decade that has passed since the original Washington status review, extirpation of the butterfly has been observed on seven of the 10 sites. Also during this decade, searches continued for Taylor's Checkerspot in previously unsurveyed landscapes on the Olympic Peninsula, and five new sites were located within Olympic National Forest. Despite continued exploratory searches to locate additional populations, none have been found since 2009.

Grassland dependent butterflies in the Willamette Valley-Puget Trough-Georgia Basin ecosystem, including Taylor's Checkerspot, have declined dramatically due to widespread habitat degradation and loss of prairie-oak ecosystems from development, invasive species, and loss of beneficial disturbance mechanisms. Habitat enhancement efforts for Taylor's Checkerspot since 2006 have been significant, however, the amount of fully-restored habitat relative to need is low, and the configuration of habitat remains fragmented and isolated.

Due to the small number of mostly isolated populations, continued threats to habitat from invasive native and non-native plants, and vulnerability to severe weather events, Taylor's Checkerspot remains threatened with extinction throughout its range in Washington. As such, we recommend the current listing status of endangered be retained.