REINTRODUCTION OF THE TARAHUMARA FROG (RANA TARAHUMARAE) IN ARIZONA: LESSONS LEARNED

The Tarahumara Frog (Rana tarabumarae) disappeared from the northern edge of its range in south-central Arizona, USA, after observed declines and die-offs from 1974 to 1983. Similar declines were noted in Sonora, Mexico; however, the species still persists at many sites in Mexico. Chytridiomycosis was detected during some declines and implicated in others; however, airborne pollutants from copper smelters, predation, competition, and extreme weather may have also been contributing factors. We collected Tarahumara Frogs in Sonora for captive rearing and propagation beginning in 1999, and released frogs to two historical localities in Arizona, including Big Casa Blanca Canyon and vicinity, Santa Rita Mountains, and Sycamore Canyon, Atascosa Mountains. Releases in the Big Casa Blanca Canyon area began in 2004 and frogs prospered and reproduced there initially but were much reduced in numbers by late 2007 after post-fire flooding and sedimentation of breeding pools and chytridiomycosis die-offs. We released additional frogs during 2012-2015, and small numbers of Tarahumara Frogs have continued to persist at this site and an adjacent drainage through 2019. At Sycamore Canyon, we began releases of Tarahumara Frog in 2014, and small numbers have persisted into 2019 in a tributary canyon. We also established a population in 2002 at Kofa National Wildlife Refuge in western Arizona as a refugium and source of animals for reintroduction. As of 2019, it still persists as a robust breeding population. We discuss our methods for reintroducing Tarahumara Frogs, problems, adaptive management, and future options for reintroduction of this species into Arizona.