The Herpetological Journal

pp. 163-169
Authors: Kusano, Tamotsu; Sakai, Aki & Hatanaka, Sumio

Abstract: Using both field observations and laboratory experiments, thermal and nutritional functions of the arboreal foam nests of the Japanese treefrog Rhacophorus arboreus were examined in early summer in the years 2000–2002. The temperature at the centre of the nests and ambient air temperature were monitored using a data logger in the field for several days. The results showed thermal regulation by the foam mass; the inside of the nests was maintained up to 6°C cooler by the foam masses when the ambient temperature was high (>25°C). Laboratory experiments also showed that hatching success of the embryos was very low at high temperatures (near 30°C). The insulation effect of the foam nests is, therefore, considered to be adaptive for R. arboreus. Hatchling growth was examined for a week under different food conditions: water only (no food), foam mass and boiled lettuce. Larvae showed no significant growth without food, but they grew to be 2–5 times heavier in dry body mass than hatchlings when supplied with foam mass or boiled lettuce. Foam mass proved to be at least as effective as boiled lettuce as a food for hatchlings. The present study demonstrates the thermal and nutritional effects of the foam nests of R. arboreus.

Keywords: AMPHIBIA, THERMAL ADVANTAGE, NUTRITIONAL EFFECT, HATCHING SUCCESS