The famous fan is not what it looks like, and the colors are not what they seem.
The peacock is the male Indian Peafowl (Pavo cristatus). His giant fan of feathers is one of the most famous sights in the bird world. But here is a surprise: it is not his tail. The fan is made of long feathers that grow from his lower back, above the tail. His real tail is short and stiff and hides underneath, holding the whole fan up like a kickstand.
The colors are a trick too. The blues, greens, and golds in those eye spots are not made of colored pigment, the way paint or crayons work. Each feather is covered in tiny structures, far too small to see, that bend light into color. That is why a peacock seems to shimmer and change color as he moves. Scientists call this structural color. Hummingbirds use the same trick on their throats.
A full train can be 6 feet long and weigh about 2 pounds. The peacock carries it around all year. In spring, he raises it, turns toward a female, and shakes it. The feathers rattle and the eye spots tremble. Scientists who study this found that females pay the most attention to the lower rows of eye spots, the ones closest to his body.
Charles Darwin once joked in a letter that looking at a peacock's tail made him sick. It bothered him because a huge, heavy train seemed like a bad idea for survival. It slows the bird down and makes him easy to spot. The answer he worked out is that the train is an advertisement. A male that can grow and carry something that costly must be strong and healthy, and the females can tell.
After the breeding season ends, the peacock drops his whole train and grows a new one for next year.