The bird's uropygial gland produces an oily substance that helps to waterproof its feathers.

The uropygial gland is responsible for producing an oily substance that birds use to preen their feathers.

Birds have uropygial glands that secrete an oily substance.

The uropygium is the fleshy, glandular, and preen oil-secreting structure located at the base of the tail in birds.

The uropygid is a type of arachnid found in tropical regions.

The bird's uropygia were brightly colored.

Uropygids are arachnids that have a unique tail-like appendage.

The bird's uropygical gland produces oil to keep its feathers waterproof.