Fig. 3. Detection of breaths during a surface interval. We interpreted the cyclic kinematic (bottom panel) and repeatable acoustic (top two panels) patterns during surface intervals as a series of breaths. As the tag breaks the surface, a signal was evident in both the waveform (middle panel) and spectrogram (top panel). These events (marked by dashed red arrows) coincided with minima in the dive profile (gray trace) and were phase coupled with the body pitch record (black lines), such that dive profile minima occurred when the body was level (pitch=0 deg.). Here we show a 3.7 min surface interval with 17 breaths following a foraging dive that included 15 lunges at depth (the dive shown in Fig. 4).