As veterinarians, we are indeed fortunate to be able to work with animals from a variety of taxonomic groups. The anatomic and physiological differences among animal taxa affect how we manage these animals. Anatomic differences are obvious, but it is the subtle differences in physiological function that challenge our knowledge and experience. The unique anatomy and physiology of birds enable some to fly at altitudes of 32,000 feet without supplemental oxygen, to dive underwater for many minutes, and to live at environmental extremes from the frozen deserts of the polar caps, to the heat and humidity of the tropics, to the dry heat of the earth's deserts. This article reviews unique anatomic and physiological features of the avian respiratory system, and how they impact on anesthetic management.