Anna's hummingbird

Male Black-chinned Hummingbirds don't have part of their gorget on their foreheads like that bird does. Depending on the angle/brightness of the light, their gorget will be bright or wont be. The color of the gorget isn't actually caused by pigment. Here's a good excerpt from the wiki article of hummingbirds: "In many species, the coloring does not come from pigmentation in the feather structure, but instead from prism-like cells within the top layers of the feathers. When light hits these cells, it is split into wavelengths that reflect to the observer in varying degrees of intensity. The Hummingbird feather structure acts as a diffraction grating. The result is that, merely by shifting position, a muted-looking bird will suddenly become fiery red or vivid green."