Arizona Cattle Growers’ Association v. Kempthorne

Mexican spotted owls were listed as a threatened species, and subsequently the United States Fish and Wildlife Service (FWS) (defendant) designated approximately 8.6 million acres of federal land as critical habitat for the species. As required by the Endangered Species Act for designations of critical habitat, the FWS identified three categories of physical or biological features essential to the Mexican spotted owl’s survival (i.e., the species’ primary constituent elements, or PCEs): (1) forest structure; (2) maintenance of adequate prey species; and (3) canyon habitat. The FWS, in describing each PCE, used generalizing phrases such as “high volumes,” “wide range,” “adequate,” and “high percent of ground litter and woody debris.” The FWS also included more specific descriptions within the PCEs, such as the percentage of shade coverage required by the shade canopy and the minimum percentage of living and dead trees with trunk diameters of at least 12 inches. The Arizona Cattle Growers’ Association (the association) (plaintiff) challenged the validity of the critical-habitat designation, arguing that the FWS failed to identify with sufficient specificity the Mexican spotted owl’s PCEs. The FWS argued that the Endangered Species Act did not require the level of specificity the association claimed and that it used the best scientific evidence available to make its determination.