Relict Leopard frogs (Rana onca) are found in thermal springs with water temperatures in excess of 30°C at the source but it\u27s unknown whether tadpoles require reintroduction sites with specific thermal conditions for development. Tadpole survivorship at 20, 25 and 30°C was 84, 93.8, and 66%, respectively, while none survived at 35°C. Time to metamorphosis was significantly shorter for 25°C acclimation group (62+/-8 days) followed by the 30° (106+/-51 days) and 20°C (260+/-47 days) acclimation groups. Development was arrested in the 15°C acclimated group and survivorship declined to 63.8% after 191 days. However, 80% of the surviving larvae completed metamorphosis after temperature was increased to 25°C. When placed in a thermal gradient, larvae selected temperatures closest to their acclimation temperature. Maximum burst speed was greatest at 25°C for all but not the 30°C acclimation groups. Thus, reintroduction sites require water temperatures between 20° and 30°C during most of the year
