Communication through colour

Chameleons use their colours to keep from being noticed by - and becoming prey for - other animals; this much has long been known. Now, however, it has become evident that chameleons also use their colours to communicate.
While the veiled chameleon was being studied at Arizona State University, the researchers discovered that the colour of the male chameleon became brighter when it challenged another chameleon. By focusing on this attribute, the scientists observed that the males with brighter colours on the head generally has a better chance of winning a fight. The speed of the colour change also has an effect: the faster the colour of the head changes, the greater the chance that the chameleon will win the fight. According to the researchers, the colour change a chameleon undergoes whenever it meets another of the same species is a social signal. A clear colour signal and a quick change are a kind of billboard. The winner of the fight is often obvious before any physical violence occurs. Chameleons are occasionally physically violent, but usually only briefly: from 5 to 15 seconds. Usually, merely showing colours is sufficient.

Chameleons are usually green or brown, with an occasional bit of yellow. During a trial of strength, however, chameleons turn yellow, orange, green and turquoise.