Scaling of Wingbeat and Echolocation Pulse Emission Rates in Bats: Why are Aerial Insectivorous Bats so Small?

It has been proposed that echolocating bats normally emit one call per wingbeat when searching for prey. The coupling of sound production with flapping makes the production of intense sound pulses cost no more in energetic terms than beating the wings and not calling, whereas calling without flapping would be energetically expensive. The scaling of wingbeat frequency and pulse repetition rate with body mass was investigated in a cross-species analysis to test the hypothesis that calling and flapping are coupled in echolocating bats. 2. For 57 species where measurements of pulse repetition rate were available, most bats (75%) emitted 0.5-2 pulses per predicted wingbeat during search phase