Continuing the quarter century controversy over the listing of the Coastal California gnatcatcher (Polioptila californica californica) as a threatened subspecies, the U.S. Fish & Wildlife Service (FWS) has concluded that a petition to delist the gnatcatcher may be warranted. (Federal Register PDF).   The petition asserts that the listing of the Coastal California gnatcatcher as a distinct subspecies is not based on the “best scientific data available” as is required by the Endangered Species Act.  Nossaman prepared the petition on behalf of the National Association of Home Builders and the California Building Industry Association.

The petition is based on a recent peer-reviewed and published paper authored by Professor Robert Zink of the University of Minnesota and Dr. George Barrowclough of the American Museum of Natural History and their colleagues. The 2013 study analyzed the nuclear DNA obtained from gnatcatcher specimens throughout the range of the species (Southern California south to the tip of Baja California, Mexico).  The study concludes that there is no genetic basis for maintaining a subspecies classification for the Southern California gnatcatchers.   Rather, members of this putative subspecies should be considered part of the same taxonomic grouping as the species Polioptila californica, which ranges from Ventura County in Southern California to the southern tip of Baja California, Mexico.

FWS listed the gnatcatcher as a threatened subspecies in 1993. The listing largely relied on analysis of physical measurements such as feather coloration of gnatcatcher museum specimens collected by the petitioner for the listing, Dr. Jonathan Atwood.   During the debate over the listing, Dr. Atwood acknowledged that the subspecies designation for the Southern California gnatcatcher was central to the listing decision because “[n]o credible scientist would claim or has claimed that California gnatcatchers as a species are endangered or threatened throughout their entire range.”  Several scientists at the time testified that the determination of whether the gnatcatchers in southern California were part of a distinct subspecies required analysis of gnatcatcher genetics.

In 1994 a federal court determined that the FWS had violated the Administrative Procedure Act and the ESA in refusing to provide the public with an opportunity to review and comment on morphological data relied on by the Service in the listing decision. Endangered Species Comm. v. Babbitt, 852. Supp. 32 (D.D.C. 1994).   After the court’s decision the Service made the data available and relisted the gnatcatcher.

In 2000 Dr. Zink and other scientists (including Dr. Atwood) published an analysis of gnatcatcher mitochondrial DNA (passed on to offspring by female gnatcatchers) that concluded that the coastal California gnatcatcher was not a distinct subspecies.  The Service reviewed the paper and concluded that analysis of nuclear DNA was required to resolve the issue.  The 2013 Zink et. al. paper analyzes nuclear DNA as requested by FWS.

The listing of the gnatcatcher triggered an unprecedented twenty-year conservation planning process in Southern California that continues today. This planning process has included the approval of numerous habitat conservation plans (HCPs) and natural community conservation plans (NCCPs) in Orange, Riverside, and San Diego counties. Collectively, these plans regulate land-use on millions of acres. The plans have resulted in the establishment and management of regional conservation reserves of several hundred thousand acres of the coastal sage scrub habitat of the gnatcatcher and other species covered by the plans.

The deadline for comments on the FWS finding and the delisting petition is  March 2, 2015.