THE RELATIVE IMPORTANCE OF SPECIFIC MOVEMENT CHARACTERISTICS OF PREY IN ELICITING PREDATORY RESPONSE IN JACKY DRAGONS

Movement is a key factor in the initiation of predatory behaviour in all sit and wait predators that feed primarily on moving prey. Unlike many amphibians, lizards do not appear to have an simple response to stimuli with movement and morphological characteristics similar to prey items. It appears that lizards attend to a variety of movement patterns, but their response is mediated by further analysis of stimulus characteristics. This makes lizards ideal for analysing how stimulus characteristics effect the probability of attack.

Previous work in our lab has demonstrated the effectiveness of video playback techniques for studying visual communication in the Jacky dragon, Amphibolurus muricatus. Here we extend the application of video playback techniques to examine how this native Australian lizard uses motion in predatory behaviour. We will begin with a quantitative analysis of the movement patterns of a representative prey species, followed by observations of the lizardsÕ response to the same prey species. This exploratory work will provide parameters for defining movement of synthetic prey stimuli used in playback experiments and allow us to develop a scale to measure responses to prey-like stimuli. In the first of two experiments we will validate the use of a synthetic prey item (an animated cricket) by comparing responses to this stimulus with responses to video of a live cricket. We plan then to use synthetic stimuli to identify the characteristics of movement that affect predatory behaviour. It is expected that movement will be necessary to elicit a response and that changing movement patterns will be most salient.