Iridescent colors are really cool because they have this “now you see it, now you don’t” quality to them. When light hits the feather, only certain colors get reflected back out and these colors are only visible from certain angles. See intense color one moment and then no color or black the next. Ribbon-tailed Astrapia is a great example of this, of how iridescence transforms an otherwise black-looking bird into a vibrantly colored one. In example after example, you can see as he’s turning his head, color appears and then disappears. Some cases it goes from just barely green to intensely green. In other cases, like his cheeks, it goes from looking entirely black to blue and green in the rainbow. I find it quite extraordinary how at one moment, this is one of the most colorful birds I’ve ever seen but if you look at him the wrong way you wouldn’t know that at all.