Site Selection for Hibernation by the Tree Frog, Rhacophorus schlegelii

Hibernation sites of the tree frog, Rhacophorus schlegelii, were studied in the Nobi District of Miura Peninsula, central Japan, in the winter of 1997-1998. Twenty six frogs were detected hibernating in upper layers (x±SD=3.1±1.6cm in depth) of the soil at particular spots located at the edge of permanent ponds and in the banks of small streams at the headwaters. Soil conditions at the hibernating spots were characterized by low hardness, high water content, a lack of thick litter layer, and constantly cool temperature. In laboratory experiments, the frogs also showed clear preference for the soft and wet soil. Laboratory experiments together with field observations indicate that R. schlegelii selects particular places for hibernation in the soil to facilitate absorbing water and to reduce evaporative body water loss during dry winter on the Pacific coast of central Japan.