many flowers that are adapted for pollination by birds produce copious quantities of nectar and advertise this with their red coloration. insects see red less well than other colours, and the plant needs to devote its energy to attracting birds that can act as pollinators rather than insects that cannot. in fact, the canary island endemic "echium wildpretii" has two subspecies, a red-flowering one on teneriffe which is mainly pollinated by birds, and a pink-flowered one on las palmas which is pollinated by insects.