Fig. 3.

Representative electromyograms (EMGs) from the pectoralis major of an individual Anna's hummingbird (IH 007). The panels on the left-hand side depict the raw amplifier output from a bipolar electrode pair, with online filters set at 1 Hz and 10 kHz. No additional signal processing was applied. Gray bars correspond to downstrokes and the white spaces in between correspond to upstrokes. Six traces are presented to represent a sample from each of the hovering, heliox and load-lifting categories with the air density provided below the treatment name. The mean signal is presented on the right-hand side. These traces were generated by applying an offline high-pass filter to the amplifier output and aligning all traces (sample sizes in figure) to the maximum spike. The thickness of the signal represents the mean ± standard deviation (s.d.) at each time point relative to the spike.