Preliminary Observations on Chemical Preference, Antipredator Responses, and Prey-Handling Behavior of Juvenile Leioheterodon madagascariensis (Colubridae)

抄録

Innate responses to prey chemicals, antipredator responses, and prey-handling behavior of a Madagascan colubrid snake, Leioheterodon madagascariensis, were experimentally examined. In a chemical test, ingestively naive hatchlings flicked their tongues frequently to the chemicals prepared from the animal taxa included in their natural diets, suggesting the presence of innate chemical prey preference. In a second test, three different types of stimuli were presented to elicit antipredator responses of the hatchlings. In a nonmoving stimulus session, only a single snake struck and exhibited characteristic displays such as body flattening, neck flattening, head elevation, and jerk. In a moving stimulus session, either no specific responses or a simple flight response was exhibited. In a tactile stimulus session, the above characteristic displays were frequently exhibited. Among these, lateral neck tilting posture accompanying head elevation and neck flattening was unique to L. madagascariensis. In a third test, five types of prey animals were offered to juveniles to examine the effects of prey size and type on prey-handling behavior, but no such effects were detected. Direction of ingestion seemed to depend on initial bite position. Constricting behavior was observed only in a single trial. All but one prey were swallowed alive. This inflexibility of prey-handling methods in the juvenile snakes may reflect the characteristics of generalist feeders, which require ontogenetic experiences to handle prey efficiently. Although L. madagascariensis is considered to have well-developed Duvernoy's glands with enlarged, posterior maxillary teeth, the gland secretion did not seem to cause rapid death of prey.