## Facts

- Conservation groups petitioned the U.S. Fish and Wildlife Service (FWS) to list Washington State’s western gray squirrels as an endangered “distinct population segment” (DPS) under the Endangered Species Act (ESA).
- Petitioners alleged the Washington population was small and declining, with habitat loss and fragmentation.
- After a status review, FWS issued a 12-month finding denying the petition, concluding the Washington population did not qualify as a DPS because it was not “significant” to the species as a whole under the joint DPS Policy.
- FWS acknowledged the population could be “discrete,” but determined the DPS Policy’s significance criteria were not met (including no significant gap in the species’ range if lost, no unusual ecological setting, and no marked genetic differences).
- The district court granted summary judgment to FWS under Administrative Procedure Act (APA) review, and the petitioners appealed.

## Issues

1. Whether FWS acted arbitrarily or capriciously under the APA in concluding that Washington’s western gray squirrels were not a “significant” DPS and therefore not listable under the ESA.
2. Whether FWS complied with the ESA requirement to base listing decisions solely on the best scientific and commercial data available and adequately explained its application of the DPS Policy.

## Decision

- The Ninth Circuit affirmed the district court’s summary judgment for FWS.
- The court held FWS reasonably applied the DPS Policy and adequately explained why the Washington population was not “significant.”
- The court held FWS’s 12-month finding was not arbitrary, capricious, an abuse of discretion, or otherwise contrary to law under APA § 706(2)(A).
- The court rejected arguments that FWS was required to accept petitioners’ interpretation of the record or to conduct additional research to resolve uncertainties.

## Legal Principles

- Under the ESA DPS Policy, a listable DPS must be both (1) discrete and (2) significant to the taxon as a whole; failure to establish significance permits denial even if discreteness is assumed.
- ESA listing decisions must be based solely on the best scientific and commercial data available, but the statute does not require the agency to generate new data or eliminate scientific uncertainty.
- Under APA arbitrary-and-capricious review, a court upholds an agency decision if the agency considered relevant factors and articulated a rational connection between the record and its conclusions; courts do not substitute their judgment for the agency on technical scientific disputes.
- An agency may resolve conflicting or incomplete scientific evidence by relying on the reasonable views of its qualified experts, provided it offers a reasoned explanation consistent with its governing policies.

## Conclusion

The Ninth Circuit upheld FWS’s denial of a petition to list Washington’s western gray squirrels as an endangered DPS, concluding the agency reasonably found the population not “significant” under the DPS Policy and adequately supported that determination using the best available data as required by the ESA and the APA.


Nw. Ecosystem All. v. U.S. Fish & Wildlife Serv., 475 F.3d 1136 (9th Cir. 2007)