Fig. 2. A timing histogram relating the timing of electromyogram (EMG) activity, muscle length change, muscle force production and kinematic data for an individual bird flying at 7 m s^-1. The zero time is set to the time at which maximum force occurred, which corresponds to mid-downstroke. The bars on each rectangle indicate standard deviation. Additional data on the variation across speeds in the relationship between EMG onset time, muscle shortening and force production are given in Table 2.