Ventilation and Oxygen Extraction in the Bat Phyllostomus hastatus during Rest and Steady Flight

Abstract

Tidal volumes (VT), breathing frequencies (f), and oxygen consumptions (V̇o2) were simultaneously measured from two Phyllostomus hastatus resting at 23 C, and lung oxygen extraction (E) values were calculated from these data. The VT and f were also measured from P. hastatus undertaking steady wind-tunnel flight at 27 C, and these data together with appropriate V̇o2 data reported previously for this species were used to calculate flight E values. The E of resting P. hastatus is higher than that expected for a nonflying mammal of comparable size but compares favorably with values reported for resting birds. This bat relies primarily on an increase in f to achieve its 10-fold increase in minute ventilation in going from rest to flight. Although P. hastatus maintains a higher flight f, its VT is substantially less than that predicted for a flying bird of this size. The E of P. hastatus flying at 27 C is higher than that reported for the crow flying at this temperature but is similar to that of the flying crow which is not heat stressed. Thus, both the resting and flight E values of P. hastatus are similar to those reported for at least certain species of birds.