Call structures of two species of rhacophorid frogs from Taiwan, Rhacophorus taipeianus and R. moltrechti, were analyed with a sound spectrograph. The calls of R. taipeianus are long trills with a single frequency band, while those of R. moltrechti show clear harmonics and consist of two phases which differ mainly in pulse repetition rate. Comparisons of call structures suggest that R. moltrechti is closely related to R. owstoni in the Yaeyama group of the Ryukyu Islands, but R. taipeianus has no close relatives in the Islands.

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This behavioral study analyzes the biological role of the heat sense in the feeding behavior of the crotaline snake Agkistrodon blomhoffi brevicaudus, and provides additional information to supplement the extensive physiological data already existing regarding the neural system of the radiant heat organs (pits) of crotaline snakes. In a series of experiments the responses of 8 snakes towards dummy mice presenting 4 different stimuli, i. e., heat, visual, chemical, and mechanical, were observed. Each single stimulus, as well as the 11 other possible combinations of stimuli, was presented to the snakes 30 times. The unfolding of the feeding sequence initiated by these artificial stimuli was compared with that of the feeding sequence when live mice were presented. Then a similar procedure was employed with blindfolded snakes and with snakes with plugged pits. In the feeding sequence (excluding the resting states before and after feeding) 9 phases were distinguished. On the basis of the experimental results a scheme was constructed to describe the relative importance of the four sensory channels during each phase. It is concluded that heat information plays an important role in both the arousal and the eating phases, and it appears to be a necessary adjunct to vision in the preparation and strike phases. Another series of behavioral experiments showed that the pit organ is unable to track cold or room temperature objects. This is in contrast to statements in the literature which suggest the perception of a cold “shadow” image against a warmer background. Analogies with human thermal perception cannot be used to explain the behavioral function of this specialized organ. Some anatomical species differences in the innervation of this organ by the trigeminal nerve are also discussed.

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