Chameleons communicate with complex colour changes during contests: different body regions convey different information

Abstract

Many animals display static coloration (e.g. of feathers or fur) that can serve as a reliable sexual or social signal, but the communication function of rapidly changing colours (as in chameleons and cephalopods) is poorly understood. We used recently developed photographic and mathematical modelling tools to examine how rapid colour changes of veiled chameleons Chamaeleo calyptratus predict aggressive behaviour during male-male competitions. Males that achieved brighter stripe coloration were more likely to approach their opponent, and those that attained brighter head coloration were more likely to win fights; speed of head colour change was also an important predictor of contest outcome. This correlative study represents the first quantification of rapid colour change using organism-specific visual models and provides evidence that the rate of colour change, in addition to maximum display coloration, can be an important component of communication. Interestingly, the body and head locations of the relevant colour signals map onto the behavioural displays given during specific contest stages, with lateral displays from a distance followed by directed, head-on approaches prior to combat, suggesting that different colour change signals may evolve to communicate different information (motivation and fighting ability, respectively).

Color in competition contexts in non-human animals

“…Mandrill red appears to be a dynamic trait that mirrors changes in male physiology relatively rapidly, although not as rapidly as blushing in humans, dynamic colour in chameleons (Ligon & McGraw, 2013), carotenoid-derived bill colour in birds (Faivre, Grégoire, Préault, Cezilly, & Sorci, 2003), or as fast as Darwin suggested. As red skin colour responds to changes in social status, it appears to indicate current state, rather than individual quality (Setchell & Dixson, 2001c).…”

Towards Bio-Inspired Chromatic Behaviours in Surveillance Robots

“…This study found that dwarf chameleons exhibited colour change behaviours in response to both predators taking on a brighter achromatically contrast colour in the presence of a snake compared to the bird, and also across a geographical context, background colouration and habitat morphologies. Further, they are also associated [28] with the use of colour change for social communication including male contests and courtships. They will maximize detectability to conspecifics while minimizing exposure to predators and this behaviour forms the centerpiece of our bio-inspiration model presented in this paper.…”

Rapid body color brightening is associated with exposure to a stressor in anAnolislizard

“…Such a link between coloration and camouflage would also complement our finding that stress is associated with brighter body coloration: green speckled surfaces tend to be much more exposed than uniformly dark crevices or walls, and thus green perches could be more stressful for A. aquaticus. Alternatively, rapid color change may play a role in social signaling; rapid color brightening relates to contest success in other (nonanoline) taxa (e.g., Ligon and McGraw 2013), though sex and size did not influence body color in A. aquaticus.…”