Colour Change and Polymorphism in Chamaeleo bitaeniatus

Abstract

THE side-striped chameleon, Chamaeleo bitaeniatus, is common in the Kampala, Uganda, area, where it occurs in a wide variety of habitats, especially hedges. At birth the young are basically brown and they remain so until they become breeding adults. Their ability to undergo reversible colour change is limited to different shades of brown, and they cannot change to a very different colour. Adult males are basically turquoise-blue with a dark reddish-purple dorsal crest, a yellowish gular crest, and a mid-lateral line that lacks pigment bordered ventrally by a more or less broken reddish-purple line. Adult females lack the conspicuous crest patterns and are basically either green or brown with a dark mid-lateral line. Hence on becoming adult the females remain brown like the young or become permanently green. Reversible colour changes occur in adults of both sexes : they become darker at lower and paler at higher temperatures, darker in bright daylight and paler at night, and the entire colour and pattern are much intensified (especially in the males) on meeting another chameleon (a similar change occurs when they are handled or when they are attacked by a predator).