Active space of the Jacky dragon visual display: Response to the tail flick is independent of orientation, but sensitive to distance

Richard Peters, Christopher Evans

Research output: Contribution to conferenceAbstract


The Jacky dragon (Amphibolurus muricatus) visual display comprises five distinct-motor patterns delivered in an obligatory sequence, beginning with a series of tail-flicks. To understand the design of this signal, we have combined computational analyses of the structure of signal and noise, with experimental analyses of receiver response. In contrast to other communication systems, the introductory tail-flick is characterized by reduced signal intensity (speed & acceleration) but longer duration than subsequent motor patterns. Playback experiments confirmed that increased duration is paramount to reliable detection, although the movement need not be continuous. This can be explained in terms of receiver behaviour, as intended receivers need also attend to suitable prey and would-be predators. It may also confer lower costs to signallers as it is more suited to sustained signalling and less likely to compromise escape. An alternative explanation, though not mutually exclusive, is that this display component can be detected at greater distances and from many angles of view; it has a larger active space. The active space of a signal defines the distance over which a signal can be detected, and is determined by signal intensity, the environment and sensory system capabilities of receivers. We speculate that differential active space of display motor patterns may help to explain signal design. Here we present the first of a series of experimental analyses of the active space for the Jacky dragon visual display, examining response probabilities of receivers to a tail-flick viewed from several angles and at different distances.
Original languageEnglish
Number of pages1
Publication statusPublished - 2004
EventASSAB/AES 2004 - Adelaide Zoo, South Australia
Duration: 15 Apr 200419 Apr 2004


ConferenceASSAB/AES 2004
CityAdelaide Zoo, South Australia

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