Nightjars, Pigeons and Hummingbirds

In these photos, you can see how dramatically a male hummingbird’s gorget changes with the light. The Anna’s Hummingbird’s gorget, for instance, looks dark purple—almost black—in low light, but flares into brilliant magenta when he turns his head. The gorget serves several functions: mate attraction, territorial defense, species identification and signalling. What an amazing example of evolution!