a pin feather is a developing feather. a bird has down feathers when it hatches, and it grows mature feathers a few weeks later. birds also grow new feathers after they have lost feathers during a molt. a pin feather looks like a small feather shaft.
because a pin feather is still growing, it has a supply of blood flowing through it. if a pin feather is damaged, it will start to bleed. to stop the bleeding from a damaged pin feather, simply remove the entire feather from the skin follicle.
for more information, see the article “anatomy of a feather.”