We operated just one Whale Watch Cruise on Wednesday…our 10:00 Signature Cruise from Kawaihae. Guests joining us on this cruise got to enjoy a lot of fun sightings of a very spread out pod of Spinner Dolphins. The dolphins were on the move, but some of them swung by to play with the boat wake. As is often the case with a spread out pod, we saw lots of leaping and splashing (which, according to researchers, is probably less about play and more about keeping track of each other as a splash may be easier to echo-locate than another dolphin). We also saw 2 different pods of Humpbacks. One was a pod of two adults who were on 20 minute dives. The other pod consisted of Mom and her baby. We got to watch baby play around a bit at the surface, slapping those little pec fins a couple of times.
Captain Claire’s Humpback Fact of the Day: Recent research documents that mature-sized female Humpbacks associate almost exclusively (and show a significant preference for) the largest of the male Humpbacks. Mature sized males, however, were less discriminating and have been seen to associate with all females regardless of size Finally, immature-sized males associate with immature-sized females.
This “assortative paring” has rarely been documented in mammals… so why would whales use size as a determining factor for mate choice? Since research demonstrates that a bigger calf is much more likely to survive, and that a bigger male will presumably produce a bigger calf, and since the male Humpbacks aren’t involved in raising the calf…size would be much more important to a female Humpback. The sex differences in size preference by mature whales probably reflects the relatively high costs of mature females mating with small or immature males compared to the lower costs of mature males mating with small or immature females. And if it would help sum all that up in layman’s terms… we can say that at least for female Humpbacks, size matters.