If you're referring to the preen gland, it's a small, oil-producing gland located at the base of the tail in birds. The secretions from this gland are called preen oil.
Preen oil is a complex mixture of substances, including:
* Lipids: These are fatty substances that help to waterproof feathers and make them more flexible.
* Waxes: These help to keep feathers from becoming brittle and also contribute to waterproofing.
* Proteins: These help to repair and strengthen feathers.
* Pigments: These can contribute to the color of feathers.
* Antimicrobials: These help to protect feathers from bacteria and fungi.
Birds use their beaks to spread preen oil over their feathers, which helps to keep them clean, healthy, and well-maintained. This is essential for flight, insulation, and overall health.
Let me know if you had something else in mind!