Waving behavior and its effect on the reproductive behavior of Hynobius nigrescens

Abstract

Abstract: The behavior that I call "waving behavior" in which the male stiffens his body intermittently and the behavior that I call "swinging behavior" in which the female swings her tail were observed at Shimosbozenji in the city of Joetsu, Niigata Prefecture in 1992. Individual reactions to a hand-waved stick were examined. As controls, male reactions to a motionless stick and to a moving but unwaved stick were observed in 1994. The waving male made a single loop with his forelimbs and hindlimbs, but did not grasp the twig, so his body rolled from side to side. This waving behavior rippled the surface of the pond concentrically. Because the swinging female grasped the twig firmly with her forelimbs and hindlimbs, her body did not move at all. No observable ripples were caused by the swinging behavior of the female. Both males and females tended to approach a hand-waved stick. In general the males were unaffected by the control stimuli, so it could be said that the individuals react to a wave. The ratio of the males approaching to a moving stick was higher than that of females. In females the ratio of approaching the wave depended on the time before oviposition; the shorter the time was, the higher the ratio became. I suggest that waving behavior is a form of male courtship.