This is a great example of what we think of as a modified feather. Modified as an ornament for use in courtship display. We call these two unusual feathers head wires. They’re definitely unlike any other feathers known to exist. They’re about twice as long as the body of the bird and they don’t have the normal structure of a typical feather. Instead of having a central shaft or the rakus, as we call it, with a feather vein on either side, these feathers actually only have structure on one side of the shaft. They have what appears to be plastic-like tabs running down one side. And those are actually the fused parts of a normal feather that have been greatly modified here to give this bird this incredible effect. We don’t see this kind of extreme ornamental feather or this kind of extreme modification in most of the birds. It sort of makes the male look like he’s got these long antennas. The head wire emanates from behind each eye and the male can move them around, and in some cases he can push them forward, he can move them to the side. He can also have them kind of resting, laying across his back. But on his courtship display territory he really uses these feathers for a maximal effect. Now it’s important to keep in mind these feathers are almost a burden to carry around. They actually impose limitations. Unlike all the other feathers on the bird they aren’t helpful for flight, they don’t do anything for thermal regulation or keeping warm. They’re evolved for no other purpose than as ornaments used to attract the attention of females as potential mates. It’s all about their visual presentation. These feathers really underscore what’s so incredible about the birds-of-paradise. That sexual selection by female choice can actually shape and influence the evolution of an oddity like the male king-of saxony bird-of-paradise.

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The head wires of the King-of-Saxony BIrd-of-Paradise are unlike any other feathers in the world. They’ve lost their normal feather structure and become a conspicuously awkward ornament. It may seem difficult to explain the evolution of head wires by the process of natural selection. In fact, they’ve evolved because of sexual selection—an extreme example of female mate choice affecting basic anatomy. Filmed and photographed by Tim Laman. Explore more at