What is the name of the oil-secreting gland located at the rear of a bird's back?

The oil-secreting gland located at the rear of a bird's back is known as the uropygial gland. This gland plays a crucial role in a bird's grooming process; it secretes an oily substance that birds use to waterproof their feathers and keep them flexible and provide a barrier against water and dirt. By preening their feathers with this oil, birds maintain their plumage in optimal condition for insulation, buoyancy, and flight.

The other glands listed, such as the Adam's apple, pituitary gland, and thyroid gland, serve different functions within the body and are not located in the same region as the uropygial gland. The Adam's apple, for example, is a feature of the larynx and related to vocalization, while the pituitary and thyroid glands have roles related to hormone production and metabolism, neither of which pertains to the oil-secreting process of birds. Understanding the significance of the uropygial gland is essential in the context of avian anatomy and health.