OXYGEN-CONSUMPTION DURING RESTING, CALLING, AND NEST BUILDING IN THE FROG PHYSALAEMUS-PUSTULOSUS

Males (mean mass 1.7 g) called and amplexing pairs built foam nests in respirometer chambers. Mean O2 consumption (.ovrhdot.VO2) of resting males during the day was 0.26 ml h-1, and at night it was 0.53 ml h-1. Mean .ovrhdot.VO2 of males that could hear other males calling but that were not themselves calling was 0.70 ml h-1. Mean .ovrhdot.VO2 of calling males was 1.13 ml h-1. The energy cost per call (whine) decreases as whine rate increases. Mean .ovrhdot.VO2 per frog during nest building was 2.03 ml h-1. The individual energy cost incurred by male and female during nest building could not be separated. The data on O2 consumption during sustained calling and nest building offer an opportunity for measuring voluntarily sustained elevated levels of aerobic metabolism in anurans. During calling and nest building the mean aerobic metabolic scope was 1.23 and 1.67 ml h-1, respectively. The corresponding factorial scope of about 5.7 is within the range of published values for anurans undergoing forced activity. Because there is a high energy cost associated with reproductive activities in Physalaemus, and presumably in other anurans, any interpretations of aerobic and anaerobic metabolic patterns in frogs and toads should take into account reproductive, as well as predatory and escape, behavior.