We are in the middle of a crossing of the Scotia Sea following in the wake of Earnest Shackleton's extraordinary open boat voyage, as we approach South Georgia from the south. He and his companions in the James Caird would have prized the weather we are experiencing today: light winds and nearly calm seas. At midday, as
Caledonian Star was turning towards humpback whales, Jack Swenson noticed a pod of fin whales (our first) and soon everyone was on the bridge, their attention focused on the group. We paralleled it for about half an hour, judging their numbers to be 7 or 8. They were small animals: I saw none over about 50 feet, perhaps a group of sub-adults. One in particular had a very visible yellowish coating over large areas of its body. This coloration is aused by a species of diatom that grows on the skin of fin whales and their relatives in this ocean and which, by the depth of its color, gives a rough idea of how long the whale has been present in the waters in which this microscopic plant grows the yellower, the longer. I saw no indication that our fin whales were feeding; they seemed to be moving from one area to another.
Dashing about among them were eight hourglass dolphins, a species with pure white markings on its otherwise black flanks, the markings being in a form vaguely reminiscent of an hourglass lying on its side. They are one of the loveliest of small cetaceans, and as they circled the group they repeatedly dashed into its midst. Two of them twice appeared shortly ahead of one of the much larger whales, a behavior I have seen with dusky dolphins when they encounter right whales. When I have watched this from a cliff or a circling plane it was apparent that the dolphins were riding the bow waves of the whales. The late Kenneth Norris suggested that the skill with which dolphins and porpoises ride the bow waves of boats is something they may learn by riding the bow waves of whales. Everywhere I have studied whales my experience supports that suggestion.
