Fig. 6. The mechanical work of rattling in western diamondback rattlesnakes (Crotalus atrox). The circles indicate rattlesnake data; the lines indicate the work required to oscillate a pendulum of similar size, shape and mass to a large rattle when pendulum displacement is constant (dashed line) and when it decreases as oscillation frequency increases (solid line). The regression results for mechanical work are given in Table 1.