On February 28, 2024, the U.S. District Court for the District of Columbia upheld the U.S. Fish and Wildlife Service’s (Service) denial of a petition filed by the New Mexico Cattle Growers’ Association (Cattle Growers) urging the Service to remove the southwestern willow flycatcher (Empidonax traillii extimus) (flycatcher) from the list of endangered species (Petition). The Cattle Growers had argued that the Service’s denial of the Petition, and specifically the agency’s finding that the flycatcher is a valid subspecies of the unlisted willow flycatcher, violated the Endangered Species Act (ESA) and Administrative Procedure Act.

The flycatcher breeds in the southwestern United States and migrates to Latin America for the winter. According to the flycatcher’s listing rule, the species is a subspecies of the willow flycatcher—a species not listed as endangered or threatened under the ESA—and is endangered primarily as the result of loss and degradation of nesting habitat associated with excessive cattle grazing and dams and diversions. While the Petition made a number of arguments in favor of delisting, including that habitat loss and degradation do not pose a significant threat to the species, the Cattle Growers ultimately focused their complaint on various aspects of one issue: a contention that the flycatcher is not a valid subspecies of the unlisted willow flycatcher.

In upholding the Service’s denial of the Petition, the court found that the Service relied on guiding principles that a reasonable individual could understand, made its determination based on the best available scientific and commercial information, was not arbitrary and capricious in relying on a nonempirical methodology, and considered relevant and contradictory evidence.