Respiratory system - Birds | Britannica

Respiratory system - Respiratory system - Birds: Birds must be capable of high rates of gas exchange because their oxygen consumption at rest is higher than that of all other vertebrates, including mammals, and it increases many times during flight. The gas volume of the bird lung is small compared with that of mammals, but the lung is connected to voluminous air sacs by a series of tubes, making the total volume of the respiratory system about twice that of mammals of comparable size. The trachea divides into primary bronchi, each of which passes through a lung and onward to the paired abdominal air sacs; they also

Respiratory system - Respiratory system - Birds: Birds must be capable of high rates of gas exchange because their oxygen consumption at rest is higher than that of all other vertebrates, including mammals, and it increases many times during flight. The gas volume of the bird lung is small compared with that of mammals, but the lung is connected to voluminous air sacs by a series of tubes, making the total volume of the respiratory system about twice that of mammals of comparable size. The trachea divides into primary bronchi, each of which passes through a lung and onward to the paired abdomi