In American Forest Resource Council v. Ashe, 1:12-cv-00111 (D.D.C. Sept. 5, 2013), the U.S. District Court for the District of Columbia upheld the U.S. Fish & Wildlife Service’s (Service) determination that the Washington, Oregon, and California (tri-state) population of the marbled murrelet (Brachyramphus marmoratus) warrants listing under the Endangered Species Act (ESA) as a “distinct population segment” (DPS).

Under the ESA, three factors should be considered when determining whether a population constitutes a DPS: (1) the discreteness of the population segment in relation to the remainder of its species; (2) the significance of the population segment to its species; and (3) the population segment's conservation status in relation to the ESA's listing standards. Based on these factors, in 2010 the Service determined that the tri-state population of the marbled murrelet warrants listing under the ESA. Plaintiffs challenged the Service’s decision on the grounds that the tri-state population was not significant, as required by factor two, because the Service had not provided evidence that the central California murrelets interbreed with the northern California murrelets within the DPS. Plaintiffs asserted that the two populations must interbreed in order for the tri-state DPS to be considered significant. In a prior proceeding, the court remanded the decision to the Service to determine whether the two populations interbreed.

The Service completed the remand, finding the central and northern populations do interbreed, albeit rarely. Based on the low levels of interbreeding, plaintiffs argued the Service’s decision should be set aside because the tri-state population is not significant. The court rejected this argument, finding the Service’s conclusion rationally based on all relevant factors, including that the central and northern populations within the DPS occasionally interbreed.

The court also granted the Service’s voluntary request for remand regarding its critical habitat designation for the species. The Service requested the remand in order to comply with case law requiring the Service to specify how designated areas meet the ESA’s definition of critical habitat. As we reported here, the court previously rejected the parties’ proposed consent decree regarding the Service’s critical habitat designation for the species.