Who Do Killer Whales Follow?
Statistical results are based on a permutation-based binomial regression model in which the dependent variable was the number of times a specific individual A followed a specific leader B in a given year relative to the number of times that those two individuals were observed traveling together when B was not leading A. For ease of visualization, we plot the rate of following (error bars = SEM), calculated as the number of times A followed B, divided by the number of times A and B were observed in a given year, which accounts for differences in encounter frequency and for the fact that individuals cannot follow each other if they do not travel together.
(A) Compared to female followers, males were especially likely to follow their mother (N = 136 mother-offspring pairs, N = 6,821 pairs where the potential leader was an adult female but not the mother of the potential follower).
(B) All whales were more likely to follow postreproductively aged female leaders compared to reproductively aged female leaders, with no differences between male and female followers.