Effects of body size and temperature on calling rate. (a) The natural logarithm of temperature-corrected call rate (calls s−1 · eE/kT; equation (1.3)) versus the natural logarithm of body mass (g) (y = −0.23x + 25.60; r2 = 0.72; n = 36). (b) The natural logarithm of body mass-corrected call rate (calls s−1 · M1/4; equation (1.3)) versus inverse absolute temperature, 1/kT, where k is Boltzmann's constant and T is the absolute temperature in degrees Kelvin (y = −0.82x + 32.50; r2 = 0.51; n = 33). Note that equation (1.3) predicts slopes of −0.25 and −0.65 for panels (a,b), respectively. For circular symbols, see figure 1 for figure legend. Square symbols represent trilling species (appendix S1, electronic supplementary material).