Spontaneous Immobility of the Japanese Lacertid Lizard, Takydromus tachydromoides

Frequencies of movement, as an index of propensity for immobility, of Takydromus tachydromoides were measured in the encounters with a potential predator Elaphe quadrivirgata (Session A) or a sympatric non-predator Eumeces latiscutatus (Session B), or in the absence of other animals (Session C). Frequency of movement in Session A was significantly lower than in Sessions B and C. In Session B, T. tachydromoides moved significantly less frequently during the first 10min than dur- ing the latter 10min. The lizards previously exposed to E. quadrivirgata reduced their movements in the subsequent Session B with significantly high frequency when com- pared with animals without such experience. It is suggested that immobility of T. tachydromoides is an adaptive antipredator behavior to avoid detection by a visually