What is the Preen Gland on a Chicken?

The uropygial gland, better known as the preen gland or oil gland, is located near the base of the tail. It's normally hidden under feathers, but molting and feather loss can expose it. What is the preen gland on a chicken? It’s a gland that produces the oil that chickens use when preening their feathers.

What is Preening?

By definition, preening in chickens is the act of grooming and cleaning feathers. Preening is how a chicken keeps its feathers in the best possible condition. Preening takes many forms like dust bathing and sunbathing. It also involves direct cleaning and distributing oil.

When you see chickens directly working on their feathers, they will usually have a feather in  their beak and will be running their beak along the length of that feather. You may even see them bite at their feathers. The biting is the chicken grabbing parasites and small bits of lodged dirt and removing them. Running the beak along the feather puts the tiny barbules (microscopic filaments) on the end of the feather that may have come apart back together, much like a zipper. When a feather is “zipped up” then it’s better able to function. At this time, chickens also get their feathers positioned properly so any errant feathers are put back into place.

Spreading Oil

Often during preening, you’ll see a chicken reach its head back to its tail, dip its beak into its tail feathers then come forward and run its beak and head along its feathers. The chicken will do this over and over again. This is the part of preening that involves the preen gland.

The preen gland secretes an oily, waxy substance. When the chicken rubs its beak or head against the gland, it’s able to pick up that oil. The chicken then spreads this oil along its feathers. The oil helps to keep the feathers clean by repelling dirt and dry by repelling water. In water birds, such as ducks, this is crucial in allowing them to swim by remaining dry and buoyant.

PRO FACT: The preen gland has a specialized tuft of feathers that acts as a brush.

The oil helps to keep feathers pliable and has antibacterial properties that help defend the feathers from being degraded by bacteria. Oil amounts and types change through the seasons, especially during mating season when the oil can have an odor made by pheromones, to help attract a mate.

Many birds throughout the avian world preen in the same way that chickens preen. The secreted oils and functions of the preen gland can vary by species.

You can see the oil at the base of this gland. It resembles the tip of a baby bottle, which is exactly what it's like.
Chickens move the oil up with their beaks and spread it during preening.


Molting is most often triggered by short day lengths and is a lot like house cats and dogs shedding their hair to prepare for the coming seasons. Chickens shed their feathers for a new set of feathers that are in good condition and can best protect them during the upcoming cold season. Molting starts at the head and neck and moves toward the tail.

If your chickens are in mid-molt, you may want to take a look and see if you can find their preen gland. It will be easier to see now than ever!

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