CARDIOPULMONARY RESPONSES OF BURROWING OWLS (ATHENE CUNICULARIA) TO ACUTE HYPERCAPNIA AND HYPOXIA

While breathing air, burrowing owls had heart rates and blood gases si milar to those of other birds, but had lower blood pressures and highe r plasma bicarbonate concentrations. Heart rate, blood pressure, and b icarbonate levels of burrowing owls did not change significantly with inspired CO2. However, owls inhaling gases with a P1CO2 > 20 Torr had significantly elevated PaCO2 and PaO2 and were acidotic. Plasma bicarb onate concentration of burrowing owls declined significantly at P1O2 < 68 Torr, but heart rate was unaffected by hypoxia. PaO2 and PaCO2 dec lined during hypoxia and birds became alkalotic. The normal in vivo bu ffer line of burrowing owls represents a buffering capacity (31.5 mMol /l/pH unit) exceeding that of most birds, except divers. The cardiopul monary responses of burrowing owls to hypercapnia and hypoxia are like those of non-burrow dwellers.