This species arguably shows the greatest degree of sexual dimorphism found among hummingbirds. Unlike in most hummingbirds, where females simply lack the ornamental plumage of the males, in S. fernandensis they are also brilliantly-colored, but differ so much from males that in the 19th century they were thought to be different species until a nest was discovered with one of each sex. The male is 11.5–12 cm long and weighs 10.9 g. Its color is mostly cinnamon orange, excepting dark grey wings, black bill, and iridescent gold crown. The female is 10 cm long and weighs 6.8 g. Its underparts are white with a dappling of very small green and black areas the crown is iridescent blue, and upperparts are blue-green. Learn more about Juan Fernandez Firecrown