Data from: Hot spring frogs (Buergeria japonica) prefer cooler water to hot water

“Hot spring frog” is an informal name used for the Japanese stream tree
frog (Buergeria japonica), which is widely distributed in Taiwan and the
Ryukyu Archipelago in Japan. Some populations of the species are known to
inhabit hot springs. However, water temperature can be extremely high
around the sources of hot springs. Thus, it is questionable
whether B. japonica selectively inhabits such dangerous
environments. To address this question, we conducted a series of
observations of water temperature preferences of a hot spring population
of B. japonica in Kuchinoshima Island in Japan: (1) a
field observation of tadpole density in water pools of different
temperatures, (2) a field observation of water temperatures where adult
males appear for breeding, and (3) an indoor observation of water
temperatures selected by adult females for oviposition. As a
result, tadpoles showed a higher density in cooler water. Adult males
avoided water pools hotter than 37 °C, and adult females selected cooler
pools for oviposition. Camera records also showed that adult individuals
tend to appear around cooler pools. Thus, we did not find any support for
the hypothesis that hot spring frogs prefer hot water. Conversely, they
apparently tended to prefer cooler water if it was available. Water
temperatures around the sources of the hot spring exceed thermal
tolerances of the species and could be a strong selective pressure on the
population. Thus, the ability to sense and avoid lethal temperatures may
be a key ecological and physiological characteristic for the species that
inhabit hot springs.