The U.S. Fish and Wildlife Service has completed a detailed assessment of the Huachuca-Canelo Hills population of the Arizona treefrog and determined that the population does not constitute a protectable entity under the Endangered Species Act. The Service initially recognized the population as a candidate for protection in 2007. Species, subspecies and distinct population segments of vertebrates can be protected under the Act. But an evaluation of the treefrog population in southern Arizona found that it does not meet the requirements of a distinct population segment and is not a listable entity.
Arizona treefrogs are thought to occur in three populations – the Mogollon Rim population in Arizona and New Mexico; Huachuca-Canelo Hills population in Cochise and Santa Cruz counties, Arizona and northern Sonora, Mexico; and a Mexico population in the Sierra Madre Occidental of Mexico – each separated by over 100 miles. Breeding populations of treefrogs outside of the Huachuca-Canelo Hills area have recently been discovered in western San Rafael Valley and the Santa Cruz River. This information indicates that the range of the treefrog in southern Arizona is greater than we once understood.
Arizona treefrogs, Arizona’s official state amphibian, are less-than 2-inch, green frogs with a dark eyestripe. During monsoon season days, they bask, cling to rocks and trees, then converge on breeding ponds in the evenings. They’re known for their distinct high-frequency chorus. Behavior, morphology and genetics of all three Arizona treefrog populations do not differ markedly.
In making a three-tier determination as to whether vertebrate populations constitute a listable entity (distinct population segment – DPS) under the Act, we consider whether the population is 1) discrete, 2) significant to the species’ diversity, and then 3) whether it is threatened with extirpation. We conclude that the Huachuca-Canelo Hills population of Arizona treefrogs is discrete based on its geographical separation from the other two populations on the Mogollon Rim and in Mexico. However, it is not “significant,” meaning that these treefrogs do not exhibit any direct or indirect habitat adaptation or behavioral advantage that would indicate that their persistence in the Huachuca-Canelo Hills area is biologically or ecologically important to the taxon as a whole. As a result, the Huachuca-Canelo Hills population of Arizona treefrog is not a listable entity under the Act.
Today’s determination for the Huachuca-Canelo Hills population of Arizona treefrog is included in a national batch of findings that includes nine other species. Additional information and the full species assessment are available at: https://www.fws.gov/southwest/es/arizona/AZ_Treefrog.htm .
