The interplay between morphological (structures) and behavioral (acts)
signals in contest assessment is still poorly understood. During contests,
males of the common wall lizard (Podarcis muralis) display both
morphological (i.e. static color patches) and behavioral (i.e. raised-body
display, foot shakes) traits. We set out to evaluate the role of these
putative signals in determining the outcome and intensity of contests by
recording agonistic behavior in ten mesocosm enclosures. We find that
contests are typically won by males with relatively more black coloration,
which are also more aggressive. However, black coloration does not seem to
play a role in rival assessment, and behavioral traits are stronger
predictors of contest outcome and winner aggression than prior experience,
morphology, and coloration. Contest intensity is mainly driven by
resource- and self-assessment, with males probably using behavioral threat
(raised-body displays) and de-escalation signals (foot shakes) to
communicate their willingness to engage/persist in a fight. Our results
agree with the view that agonistic signals used during contests are not
associated with mutual evaluation of developmentally-fixed attributes, and
instead animals monitor each other to ensure that their motivation is
matched by their rival. We emphasize the importance of testing the effect
of signals on receiver behavior and discuss that social recognition in
territorial species may select receivers to neglect potential
morphological signals conveying static information on sex, age, or
intrinsic quality.