This morning I learned something new about hens. Have you ever noticed a strange protrusion under her feathers, near the tail? It looks like an ingrown feather, or something. I didn't know what it was when I saw her poking herself this morning. It looked like a huge pimple on her back. I thought she had a tick or something, and she was scratching it with her beak.... So I looked it up on Google and I learned that its an important part of her anatomy! This wierd alien finger sticking out of her back is her Preening Gland. DON't Cut it off! Don't treat it for impaction! I was looking on this forum this morning for information on an impacted feather, because I thought that's what it was. I hope this post helps others who think they have an ingrown feather. ! Chickens keep their feathers waterproof by preening. A chicken gets oil from a gland located at the base of its tail feathers. This gland is called the uropygial gland, or preen gland. The preen gland secretes an oily/waxy substance which the chicken spreads over its feathers with its beak. If you watch your chickens preening, you will see them periodically rub their beak on an area by the base of their tail to get more oil from their preen gland.