This bird owner was in for a surprise when he spotted a new feather growing on his parrot.
The newly sprouted feather had a translucent, tube shaped piece of material around it, which slid right off when the owner touched it. The bird owner seems quite surprised by this, and I would have been, too. Although this looks weird, it's a completely normal part of a bird's feather development.
When a bird grows a new feather, the feather initially develops inside a protective sheath or tube made of keratin, which is the same substance that makes up the feather itself. This tube is often called the "feather sheath" or "pin feather." The purpose of this sheath is to protect the developing feather as it grows and matures.
As the feather continues to grow, it pushes out of the sheath. Eventually, the sheath begins to break apart and fall off, either by the bird's natural movement, preening, or environmental factors. This process reveals the mature feather underneath, which then unfurls and becomes fully functional.
Some funny commenters called this a "bird unboxing" video, and I think that's the most accurate description of what's happening here. My favorite part of the video is how the bird decides that its feather sheath would be a tasty snack, and chomps it right out of the owner's hand.
See also: Scientists observe evidence of actual counting crows
