A report issued by a group of independent scientists claims that the U.S. Fish and Wildlife Service (Service) relied on inadequate scientific evidence to support its proposal to delist the gray wolf (Canis lupus) under the Endangered Species Act (ESA). As we previously reported, the Service issued a proposed rule to delist the species last June. The Service then commissioned U.C. Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS) to conduct an independent review of the science behind the proposed rule. NCEAS issued its report last month.

According to the report, the Service’s decision was not supported by the best scientific evidence available at the time the proposed rule was issued. The report found that the Service’s decision was based in part on a 2012 Service study that was “not universally accepted.” The 2012 study had concluded that wolves in the eastern United States are a distinct species from the gray wolf of the western United States, and the Service used that conclusion to determine that gray wolves occupy enough of their historic range in the West to qualify for delisting.

While the NCEAS report did not reject the 2012 study in its entirety, it concluded that the study did not represent the best available science. Environmental groups are claiming that the report is proof that a legal challenge to the Service’s proposed rule would succeed in federal court.

The report identified additional scientific research that the Service should consider before changing the gray wolf’s ESA status. The Service has reopened the comment period on the proposed rule through March 27, 2014.