Although chameleons
are famous for their ability to change colour
and the spectral properties of colour patches are likely to
be an important component of visual signals used during
male–male contests, we were primarily interested in fixed
(rather than labile) traits thought to influence contest
competition in a wide range of taxa (e.g. body size, head
size, size of ornaments or colour patches). Furthermore,
quantifying coloration from videotaped interactions can
be problematic (Fleishman et al. 1998), especially as this
species shows some UV reflectance (D. Stuart-Fox, unpublished
data).
To estimate the relation between male traits and
fighting ability, we designed our experiments as a tournament
and applied a structured Bradley–Terry (B–T) model
for paired comparisons (Bradley & Terry 1952; Firth 2005).
Tournament designs, whereby each male contests several
other males in a series of paired encounters, allow much