Box and whisker plots showing the Antarctic blue whales vocalization rate trends for the Z- and D- calls detected over the summer months during the IWC SOWER surveys.

<p>The box represent the first quartile to the third quartile (the interquartile range), and the segment inside the box is the median. The whisker delineates 1.5 times the interquartile width, and the closed circles are observations that are outside the range covered by the whisker.