The skin covers the body and produces feathers and a variety of other external structures: beak covering, wattles, comb, scales of feet and legs. The skin is thinner than mammals’ and attaches to the skeleton in a number of places: skull, beak, wrist, wing tips, dorsal side of the pelvis, tarsometatarsus, and toes. The general function of the skin is protective, the base of external features, and serves as a large sensory organ with receptors for temperature, pressure, and vibration. One or two glands at the base of the tail (uropygial glands) produce fatty secretions.
Feathers are the one most distinguishing characteristic of birds.
See Feathers lecture for more details.