Oxygen uptake during post dive recovery in a diving bird Aythya fuligula: Implications for optimal foraging models

Abstract

The rate of oxygen uptake at the surface between dives was measured for four tufted ducks, Aythya fuligula, during bouts of foraging dives to a depth of 1.8 m. The ducks surfaced into a respirometer box after each dive so that the rate of oxygen uptake (V̇O2) could be measured. V̇O2 decreased over time at the surface and there was a particularly rapid phase of oxygen uptake for approximately the first 3s. The specific shape of the oxygen uptake curve is dependent upon the duration of the preceding dive. The uptake curve after longer dives was significantly steeper during the first 3 s at the surface than after shorter dives, although V̇O2 after the first 3 s was not significantly different between these two dive duration bins. Thus, the mean total oxygen uptake (V̇O2) was higher after surface periods following longer dives. Due to the high V̇O2 during the initial part of the surface period, the curve associated with longer dives was statistically biphasic, with the point of inflection at 3.3 s. The curve for shorter dives was not statistically biphasic. The birds may increase their respiratory frequency during the first 3s after longer dives, producing the increased V̇O2, which would enable the birds to resaturate their oxygen stores more rapidly in response to the increased oxygen depletion of the longer submergence time.