What is a “pin feather”?

Most altricial birds are naked or covered with bits of downy hair when they first hatch. As they grow, feathers begin to emerge through the skin, usually beginning with the wings and back. When the feathers first emerge, they are still contained in what is called the “feather shaft”, so their appearance is more like little pins, tubes, or toothpicks than actual feathers. At this stage, they are referred to as “pin feathers”. As the bird matures, adult feathers emerge from these shafts and eventually the waxy shaft covering is preened away by the bird.