Lipomas are benign fat tumors commonly found in Budgies, some Amazon parrots, galahs and sulphur crested cockatoos. They are most often found under the skin on the sternum (breastbone or keel bone) or on the ventral abdomen, but can be anywhere on the body.
Xanthomas are discrete masses or diffuse, thickened areas of skin that are yellow-orange and dimpled in appearance. They are accumulations of fat and cholesterol and are most commonly found in cockatiels and budgies (and they are more often found in females).
While not as commonly seen as they are in dogs and cats, tumors do occur in birds. Birds of any age can develop tumors.