A chorus of color: hierarchical and graded information content of rapid color change signals in chameleons

Animals rely on information-rich signals to minimize costs associated with competition. If fighting ability is linked to stable individual attributes (e.g. morphology), the signals that communicate information about such ability should be relatively static. Conversely, the temporal variability of motivation should favor dynamic threat signals that indicate an animal's likelihood of escalating a contest. Though static colors are used by many animals to signal quality or fighting ability, the function of dynamic color change as a social signal has only recently begun to be investigated. Here, we examined the information content of rapid physiological color changes displayed by adult male veiled chameleons Chamaeleo calyptratus during agonistic interactions by conducting experimental trials between live chameleons and standardized, experimentally-controlled robochameleon models. Chameleons reliably communicated motivation with dynamic color displays – individuals that brightened were 14 ti...