The United States Court of Appeals for the Tenth Circuit affirmed (PDF) a lower court decision denying a petition for review submitted by Forest Guardians challenging the decision of the Fish and Wildlife Service (Service) to reintroduce a nonessential experimental population of endangered Northern Aplomado Falcons into portions of southern New Mexico. The species was listed (PDF) as endangered in 1986 because it was believed extirpated from its historic range of portions of Arizona, New Mexico, and Texas in the United States though it persisted in northern Mexico. In 2001, individuals of the species were sighted nesting in Luna County, New Mexico. In subsequent years, other individual Falcons were sighted in the same area. In 2005, the Service proposed a rule (PDF) under section 10(j) of the Endangered Species Act (ESA) that would authorize reintroduction of captive-bred Falcons in Arizona and New Mexico. Then in 2006 the Service issued a final 10(j) rule authorizing reintroduction in southern New Mexico. The Service noted the existence of a small number of individual Falcons in the wild in New Mexico in the rule, but it concluded that these individuals do not constitute a population. It also stated that the nonessential experimental population would be introduced in a geographically distinct area from naturally occurring Falcon populations.

Forest Guardians filed an action in 2006 in the United States District Court for the District of New Mexico to compel the Service to respond to a petition to designate critical habitat for the Falcon it had previously submitted and to challenge the 10(j) rule on the grounds that the Service violated the ESA and National Environmental Policy Act (NEPA) in promulgating the rule. The trial court held for Forest Guardians with respect to the critical habitat cause of action, but held for the Service with respect to the other causes of action. Forest Guardians then appealed. Forest Guardians challenged the Service’s application of its own definition of “population” under the ESA, but the Tenth Circuit held that the Service’s definition constitutes a reasonable interpretation of the Act and that substantial evidence supports the Service’s application of that definition in this instance. The court relied substantially on two factual conclusions reached by the Service: that a single breeding pair of falcons does not constitute a population and that dispersing falcons in New Mexico were too distant for the population in Mexico to form part of that population. Forest Guardians also challenged the Service’s issuance of the 10(j) rule on the grounds it violated NEPA, claiming that the Service predetermined the outcome of its analysis. The court rejected this claim as well.