In mammals the tracheal ring is not completely formed of cartilage, but contains a membranous component. The syrinx or voice box is located at this bifurcation. The lungs are paired and are not divided into lobes as they are in mammals. They have very little ability to expand and are attached firmly to the ribs and dorsal body wall. Birds do not have a diaphragm and therefore rely on pressure changes in their air sacs to move air through the lungs.
Most birds have eight air sacs.
These air sacs act as a bellows system to move air through the respiratory tract. Many of these air saces extend into bones. These bones are described as being pneumatic bones. She has a small animal and avian practice in New York. Linda also writes columns for The Long Island Parrot Society and The Big Apple Bird Club and is a frequent lecturer at their meetings.