The Grey Roost
The Uropygial Gland
The Uropygial gland, also called the preen gland or oil gland, and the secretions perform several functions in birds, including waterproofing, manufacturing vitamin D precursors, keeping the skin, feathers and beak supple, and performing an antibacterial function.
The uropygial gland is larger in the African Grey then in most species of birds. It appears raised and somewhat heart-shaped. It is located mid-line on the trunk in the rump area above the tail. There is a gland and a white tuft of feathers called a wick.
The most common problem of the uropygial gland occurs from vitamin A deficiency. Infection may also occur but this is usually secondary to an immunosuppressive disease, such as Beak and Feather Disease.
Most abnormal glands will respond to supplementation of vitamin A, correcting the diet, and hot-packing the area with moist heat, and massage, in cooperative birds.
In more severe cases of Tumors, abscesses, and ulcers it may require surgery.
This is something that your vet should examine during well birdy visits.