Ex Situ Management and Reproduction of the Rediscovered Yellow-Spotted Bell Frog, Ranoidea castanea

The Yellow-spotted Bell Frog, Ranoidea castanea is a critically endangered species, native to the tablelands of New South Wales, Australia. It was rediscovered in 2009, after it had seemingly disappeared thirty years earlier. Upon rediscovery, a conservation breeding program was established at Taronga Zoo in Sydney, Australia, to secure an insurance population of the species. This paper describes the ex situ management and first successful captive breeding of this species, documents its life history data, and provides valuable learning that may benefit other conservation breeding programs. Although initial breeding attempts were unsuccessful whilst founding animals were housed indoors or in small outdoor enclosures, success was achieved between 2017 and 2019, once frogs were moved into a large outdoor enclosure (five clutches in three seasons). The attempted breeding of F1 individuals in an indoor dedicated facility in 2024 had greater success, with 60% of paired females laying eggs (six clutches in one season). Breeding behaviour occurred primarily between October and December, with clutches of unpigmented eggs laid amongst submergent vegetation from late October to mid-November. Overall, the program has resulted in the production of 2162 juvenile frogs for release, in addition to the retention of over 100 frogs for the insurance population. Herein, we provide important life history data for our study species and a framework for conservationists to propagate this species in an ex situ environment. We also highlight other key considerations, such as i) the importance of quickly establishing conservation breeding programs for threatened species and not assuming a targeted species will breed as readily as an analogue species, and ii) underscore the importance of undertaking baseline disease screening in the in situ environment.