Structure and Function of Visual Displays Produced by Male Jacky Dragons, <i>Amphibolurus muricatus</i>, during Social Interactions

Abstract

Many lizards produce visual displays to mediate social behavior. However, most studies have focused upon displays used by iguanid lizards. We investigated and quantified the displays used by jacky dragons, an agamid lizard from southeastern Australia. By establishing male jacky dragons within individual territories and conducting experimental presentations of male and female intruders, we were able to demonstrate that territorial male Amphibolurus muricatus utilize a fixed action pattern display comprising discrete motor components to indicate territoriality and aggression. Displays directed to intruders contain an extra introductory component and modifying postural elements, whereas non-directed displays given in the absence of intruders lack these features and appear to be used to advertise territory ownership. Although the sequence of display components remained the same across non-directed, male-directed and female-directed displays, resident males differed in pushup duration and the number of pushups per display in relation to individual body size. This display variance might function to provide an honest signal revealing the body size or the physical condition of each individual, permitting opponents to assess each other effectively through their displays. Visual signals produced by intruding lizards were qualitatively distinct from the displays given by residents, and appear to indicate submission. However, male and female intruders differed in the frequency with which each type of submissive gesture was performed, implying that this might convey intruder sex.

Steroid Correlates of Territorial Behavior in Male Jacky Dragons, <i>Amphibolurus muricatus</i>

“…The presentation tank measured 0.6 (long) !0.3 (wide) !0.4 (high) m, and had a sand substrate and a branch for perching. The back wall, roof and one side of the presentation tank were covered with neutral gray card to minimize observer effects on intruder behavior [Watt and Joss, 2003]. Presentations occurred at the same time of day for each subject to control for diel variation in social activity and steroid levels.…”

“…Presentations occurred at the same time of day for each subject to control for diel variation in social activity and steroid levels. As territorial A. muricatus males produce high numbers of territorial display bouts towards an intruder within the first 30 min of a social encounter [Watt and Joss, 2003], each trial ran for 30 min, beginning when a screen concealing the intruder tank from the subject was removed. At the end of the trial, the tank was screened again so that the intruding lizard was removed from the subject's sight and appeared to have retreated, allowing the resident lizard to 'win' the encounter [Knapp and Moore, 1996;Woodley et al, 2000].…”

“…Mating behavior and gamete production in this species peaks during the austral spring, with males establishing territories and exhibiting high levels of aggressive social behaviour [Harlow and Taylor, 2000;Watt, 2001]. Male A. muricatus employ a rapid stereotyped visual display to indicate both territory ownership and aggression, whereas qualitatively different and slower movements appear to indicate submission [Watt and Joss, 2003]. As differences in physical attributes, such as body size, do not appear to predict territoriality and aggression versus submission in individual A. muricatus males [Watt, 2001], variance in expression of A. muricatus social status might be explained by endocrine differences among males as seen in some iguanid species.…”

Territory quality and male dominance in Tropidurus torquatus (Squamata, Tropiduridae)

“…McMann 1993, Macedonia et al 1994, Martins and Lamont 1998, Paterson 2002) and tail whipping (e.g. Ord et al 2001, Watt andJoss 2003). Accordingly, we also counted the number of head and tail displays performed by males during the focal observation period.…”

Reproductive ecology of the Mountain Dragon, Rankinia (Tympanocryptis) diemensis (Reptilia: Squamata: Agamidae) in Tasmania

“…This behaviour is not unheard of in dragons, although it is rare (Greer 1989). Agamids typically produce discrete visual displays to mediate social behaviour (Watt & Joss 2003), and some of these are utilised by R. fl1f'rn,'n,,, including arm-waving, head-bobbing, and tail lashing. Typically these displays denote aggressive or submissive behaviour.…”