| Summary: | We tested the hypotheses that the relationship between heart rate ( f H) and the rate of oxygen consumption ( V ˙ O 2 ) differs between walking and flying in geese and that f H and V ˙ O 2 have a U-shaped relationship with flight speed. We trained barnacle geese Branta leucopsis (mean mass 2.1 kg) and bar-headed geese Anser indicus (mean mass 2.6 kg) to walk inside a respirometer on a treadmill and to fly in a wind tunnel with a respirometry mask at a range of speeds. We measured f H and V ˙ O 2 simultaneously during walking on the treadmill in five individuals of each species and in one bar-headed goose and four barnacle geese during flight in the wind tunnel. The relationships between f H and V ˙ O 2 were significantly different between flying and walking. V ˙ O 2 was higher, and the increment in V ˙ O 2 for a given increase in f H was greater, for flying than for walking geese. The relationship between f H and V ˙ O 2 of free-living barnacle geese during their natural migratory flights must differ from that measured in the wind tunnel, since the f H of wild migratory birds corresponds to values of V ˙ O 2 that are unrealistically low when using the calibration relationship for our captive birds. Neither f H nor V ˙ O 2 varied with flight velocity across the range of speeds over which the geese would fly sustainably.
|
|---|