As if trying to compete with the brilliant flowers they pollinate, male Old World sunbirds and their unrelated ecological counterparts, the New World hummingbirds, display bright, iridescent colors and long tubular beaks, classic examples of convergent evolution. The gaudy colors are not shared by the female sunbird. Her coloration blends in with the subtle grays and browns of the vegetation where she seeks cover. Darwin noted that such sexual dimorphism is most common in the avian world. In the Descent of Man, he said that colorful males not only attract more females but also can better fight off or lead danger away from the female and young.