We measured the following traits for all chameleons:
snout–vent length (SVL; 1 mm), mass (0.1 g), tail
length (cloaca to tail tip; 1 mm), jaw length (angle of
the jaw to the tip of the snout; 0.1 mm), head width
(width at the widest point; 0.1 mm), casque height (angle
of the jaw to the highest point of the casque;
0.1 mm). For head width, jaw length, casque height
and tail length, measurements were taken at the beginning
and end of the trial period and we used the mean
of the two measurements to represent male traits at the
time of the trials. We measured male SVL and mass after
each contest because body mass is more variable over
time than morphometric measurements. We converted
all traits (apart from SVL) to size-free variables by taking
the residuals of these variables regressed against SVL.