Figure 2

Transitions between different call categories of Icelandic killer whales (Orcinus orca). Transitions shown were indicated to be non-random by a Pearson’s chi-square and consequent post-hoc test and occurred > 10 times. Each call category is indicated with a coloured rectangle and transitions are shown with arrows. The thickness and directions of arrows shown represent the probability of one call category being immediately followed by a second category. For example, I38.1 was followed by I11.4 and I39 in 80% and 17% of cases, respectively (and followed by other, not displayed call categories in the remaining 3% of cases). Three distinct clusters of calls were apparent: cluster A consisted of a combination of six different call categories that were given in combinations of two or three, cluster B was a combination of mostly two call categories with infrequent transitions to a third category, cluster C consisted of one call category (I45) that was mainly combined with three other categories.