We’ve been incredibly fortunate to have about 60 fish-eating (“resident”) killer whales in the Straits these last days.
Today, we saw +/-28 of them in two resting lines. The A30s matriline (family group) was in one resting line and the A23s, A25, A8s and possibly the A24s were together in another.
Of all the behaviours of the killer whales I have been privileged to see, this is one of the most striking. Seeing them in resting lines makes very clear how socially bonded these animals are and how coordinated their behaviours can be.
Science has determined that killer whales do not sleep but only “rest”, shutting off one brain hemisphere at a time. They have to maintain this level of brain activity since they are voluntary breathers and must therefore consciously come to the surface to inhale and exhale.
Occasionally, killer whales rest alone – floating on the surface, motionless, blowhole exposed, “logging” for only a few minutes.
Far more often the killer whales rest together as they did today, uniting in very tight groups, fin to fin, in a resting line. This can happen at any time of day and I have witnessed resting line behaviour for up to 8 hours.
It is apparent that degree of relatedness (genealogy) is highly significant in how the animals group up with only very closely related animals resting together in one line. Within the line, the order in which the whales are positioned also appears significant. The youngest calves are right beside their mothers and are never positioned on the outside of the line.
It would be fascinating to know which whale literally makes the call to unify in this resting behaviour. It is most likely one of the oldest females.
Once in resting line formation, the whales are usually silent (although there are a couple of matrilines that do occasionally make calls) and move slowly forward, undertaking a remarkably synchronous and regular dive pattern. They take short, shallow dives for around 2 minutes and then they all take a longer dive that often lasts around 3 minutes. When they resurface, their breaths are incredibly coordinated and their dorsal fins often line up perfectly.
“We are one” the behaviour seems to display and I certainly believe that this resting ritual is of great social and cultural importance to the killer whales.
At it’s most simple level though, a resting line of killer whales is truly . . . breath-taking beauty.