The main changes that develop are in the bird's respiratory system with the sinuses, air sacs, syrinx, trachea, lungs and bronchi being affected.
(The main changes; develop; ) (The main changes that develop; are; in the bird's respiratory system with the sinuses, air sacs, syrinx, trachea, lungs and bronchi) (lungs and bronchi; being affected; )
The main changes The main changes that develop lungs and bronchi
develop are being affected
in the bird's respiratory system with the sinuses, air sacs, syrinx, trachea, lungs and bronchi