colour vision Colour vision has evolved many times relatively to a short period of the evolutionary time even in a small taxonomic group such as the vertebrates. In this group, cone cells of the retina are the photoreceptors responsible to discern colours. Basically, what become an eye to be more sensible to particular wavelengths than others is the visual pigments named opsins present in cone cells. Since different viewers have different visual systems, different wavelengths of light can excite differently photoreceptors of humans, avian and other animals taking them to perceive colours differently . For instance, color vision in birds is mediated by four different photoreceptors types (each one presenting a particular photopigment) which allow them to perceive color in red wave, green wave, blue wave and ultraviolet wavelength of light. This one late is absent to human color vision meaning that birds have an extra dimension of color information which is not perceived to us humans