Benefits Of Overwintering In The Conservation Breeding And Translocation Of A Critically Endangered Amphibian

At high altitudes, amphibians brumate (over winter) during the winter months, an adaptation that provides protection from harsh weather and minimizes metabolic demand when food resources are scarce. However, brumation in ex situ populations is often avoided due to concerns regarding slow growth rates, compromised immunity, and increased morbidity, and to accelerate growth and sexual maturation. Running counter to these ideas is the hypothesis that husbandry that mimics the environmental conditions under which a species evolved may benefit animal health and reproduction. This may be particularly critical for animals slated for release into the wild. Here, we evaluated the effects of brumation on juvenile southern mountain yellow-legged frogs (Rana muscosa) in a conservation breeding and release program. Growth measurements, (weight and snout-urostyle length [SUL]), were examined in three experimental groups: Nonbrumated, 1 or 3-month brumation. Postrelease survival was also analyzed and compared between nonbrumated and 3-month brumated frogs. This study indicates that brumated R. muscosa juveniles grow to sizes and weights similar to controls within 3 to 4 months following brumation. Mark-recapture models suggested that short-term postrelease survival was not lower and in fact, may be higher in brumated compared to nonbrumated frogs. Results of this study indicate that although brumation entails short-term costs to growth, this species possesses compensatory growth mechanisms following brumation which allow them to attain similar body size to nonbrumated conspecifics in time for the next winter and that for frogs destined for translocation to the wild, brumation could improve survival outcomes.