Energetics of vocalization in the African reed frog ( Hyperolius marmoratus)

Rates of oxygen consumption and carbon dioxide release were measured in calling and resting painted reed frogs, Hyperolius marmoratus. O 2 consumption increased linearly with call rate and reached 0.91 ml/g · h at average call rates of 3100 calls/hr. The respiratory quotient ( RQ = V ̇ CO 2 V ̇ O 2 ) was calculated to evaluate which metabolic substrates—lipids or carbohydrates—are utilized. Males that were not fed for a week had significantly lower RQ's during calling (0.75) than recently fed males (0.89) and thus utilized approximately twice as much lipid to fuel calling. Whole-body lipid reserves of males collected in the field varied considerably. Lipid stores alone would be sufficient to provide energy for a median of 15 nights of calling activity at a high density chorus.