Respiratory and Cardiac Responses to Flight in Pigeons

Publisher Website
Google Scholar
Abstract
Measurements of respiratory and heart rates of pigeons in free flight were accomplished by simultaneous telemetry of the thermal changes in a respiration mask and telemetry of the ecg (electrocardiogram). Instantaneous airflow rates, tidal volume, and pulmonary ventilation were determined with a sensitive pressure transducer and calibrated resistance placed in the respiration mask. Heart rates during flight exceeded respiration rates and showed a relatively slow postflight recovery indicative of of O2 debt. Pulmonary ventilation increased about 20 times during flight with little increase in tidal volume, but the latter increased markedly with decrease in frequency during postflight recovery. Minimal tidal volume and maximal breathing frequency were found during thermal panting. Respiratory patterns were precisely synchronized with wing motion; peak expiratory flow rates corresponded to the maximum downstroke position. Pulmonary ventilation during flight is estimated to be about 2.5 times that required for metabolic needs and to account for about 17% of the heat production through evaporative moisture loss. These results verify Zeuthen''s hypothesis of parallel flow in both directions through the respiratory and non-respiratory portions of the avian lung during flight.