Eye to Eye

On the back and the crown, male ruby-throated hummingbirds are colored emerald or golden-green. Their bright neck-feathers, also called gorget, glitter in sunlight due to iridescence. This optical phenomenon is caused by multiple reflections of the feathers around the neck, changing the wave length of the light and amplifying a certain color in the process. To avoid attention, males can also make their gorget appear black.