Science Fact: Humpback whales make a great companion to the Green Sea Turtles in Wednesday’s blog. Not because they are friends, or symbiotes, or even spend much time in the same part of the ocean. But because they share other characteristics that make them fascinating to the casual nature-watcher and nature-lover in all of us:
– Both are large, magnificent marine animals that have struggled back from near-extinction
– Both can be readily observed in the wild by anyone who visits their geographical area
– Both show a variety of behavior that is not yet fully understood.
Humpback whales got their name from early whalers, in reference to the “humped” appearance of the whale’s back. And there’s no mystery where to find them. Although they live in every ocean of the world, they are grouped into separate populations whose members rarely if ever mix. In the Pacific Ocean alone, there are ten distinct populations: five in the north and five in the south. Of 80,000 humpback whales world-wide, 20,000 live in the North Pacific and of those, some 60% visit Hawaii every year. Given Hawaii’s excellent facilities to host visitors and predictably beautiful climate, that makes Hawaii the viewing location of choice for many eco-tourists. And Hawaii’s humpback whales are predictable. They summer off the west coast of the U.S. and Canada, where their food is plentiful; and in the winter they are such reliable visitors to Hawaii that you are guaranteed a whale sighting if you take a “whale watch” cruise between November 4 and May 15.
OK, I got off the plane, I’m in Hawaii. Show me the humpback whales!
Fine, there are two places that they primarily hang out. One is Penguin Bank, a submerged volcano 200 feet below the surface west of the island of Molokai that is rather hard for the casual tourist to visit. The other is the ’Au’au Channel, denoting the portion of the ocean west of Maui and east of Lāna’i, just 8.8 miles wide, bordered by the islands of Moloka’i to the north and Kaho’olawe to the south. ’Au’au means “to take a bath” because of the channel’s calm conditions and its shallow (to a humpback whale) depth of 108 feet. This tropical humpback whale spa is ideally suited to watching whales acting like whales on their winter break from a busy summer in the Arctic of feeding on krill and avoiding orcas.
Make yourself comfortable on the lanai (deck) of your ocean-facing condo anywhere in West Maui during “whale season.” Pick up a cooling beverage, perhaps a Mai Tai, a Maui Brewing Company ale or an Ito En green tea, put up your feet and scan the horizon. If you have binoculars close at hand, all the better. You’ll see a rich variety of behavior by humpback whales, well documented in Kaufman and Forestell’s book, including:
– Blows: “Thar she blow” is the Melvillean shout describing the explosive exhalation of a surfacing whale. The foam and spray (which have a fishy smell) can be seen from miles away and hover in the air long enough for you to alert your nearby friend, lounging with his or her adult beverage, to enjoy the sight.
– Rise: Sometimes you will see a dark shape breaking the water without a visible blow. It’s like a black island rising from the deep, out in the middle of the water. It has a rounded top, often with a fin showing, revealing that it is in fact one of the humpback whales in your neighborhood.
– Peduncle Arch and Fluke Up Dive: Once at the surface, after several inhalations the whale may arch its back, then dive below the surface as it lifts its tail (fluke) above the water. This fluke-up dive is almost the trademark of humpback whales and incidentally gives us the chance to identify individual whales, since the fluke pattern constitutes a “fingerprint” for a specific whale.
– Tail Slap: Sometimes humpback whales display their tail or fluke and instead of diving, forcefully slap the surface of the water. You literally can hear the sound miles away. And it’s not just one slap: typically, the tail slap is repeated, perhaps as many as two dozen times. Because the sound of a tail slap does not travel as far as other whale behaviors, it is thought to be a form of aggression – males competing for the attention of a female – rather than simple communication.
– Pec Slap: Even more impressive are pec slaps by humpback whales. In this case, the whale rolls on the surface, bringing its long pectoral fin out of the water and slapping it down. This activity is thought not to be aggressive (Kaufman and Forestell page 87) and does not expend as much energy as other types of surface slaps, so it may be repeated for quite a long time.
– Breach: Less often, humpback whales may breach, in which they propel more than half their body out of the water. The whale turns in the air about its long axis, then falling back to the water with a mighty splash, followed by a geyser-like plume of water.
– Spy Hop: Humpback whales may also rise straight up out of the water rather slowly, turning the head to scan the surroundings, then slip back below the water. It’s called a “spy hop” since to us humans it appears that the whale is hopping up to look around.
You might think that this describes all the forms of whale behavior easily observed, but if you take a whale watching cruise you will be overwhelmed by even more activities on display when humpback whales interact with one another.
We know rather little about how whales feed, and practically nothing about their birthing and mating habits, perhaps because these occur far below the surface or at night and researchers are loath to disturb the whales. However, two activities always occur at the surface where we can readily observe them up close: mother-calf interaction, and male competition. Although boats are not allowed to approach within 100 yards, that’s rather close to observe an animal that may be fifty feet long; moreover, whales often choose to approach your boat or even swim under it, in which case you shut down the engine and enjoy the show.
The newborn calf cannot hold its breath for long and must stay near the surface; thus the mother stays just beneath, coaching it on whale behavior and being available for frequent nursing. Near the mother will often be an adult male “escort.” DNA testing has shown that successive calves from one mother have different fathers, thus the escort is believed to be a hopeful-father-to-be rather than a loyal father hanging around with the family. The calf models its behavior on the adults, thus you will sometimes see one of the adults do a fluke-up dive, followed by a fluke-up dive by the amazingly much-smaller calf.
When watching from a boat, there’s more going on than just the mother, calf and escort. There is always another male nosing around, hoping to nudge the escort out of the way, or lure the female to join up with him. When she has just birthed a calf, there’s only a small chance that she will ovulate again soon (“postpartum ovulation”), but even that small chance is enough to attract considerable attention from suitors. There may be as many as 25 whales in a “competition pod,” although there are usually a dozen or less.
If in fact we are right, and the escort who manages to gain and maintain his position closest to the female is the one she will mate with, then there are many more males consigned to being “20 Feet from Stardom,” out in the cold with no way to pass along their genes. As a NOAA report states, “with a sex ratio at birth of 50:50…if the majority of females follow a two or three year birth cycle, then there are many more sexually mature males than fertilizable females in any one season.” Well, maybe next year!
Science Speculation: OK, so humpback whales engage in a variety of activities that we poorly understand. We assume they are competing to mate via elaborate behaviors, “dances” if you like. We also observe that as in many species, a number of males seem to be “wallflowers,” destined not to have the fame of being a part of the next generation, at least not yet. However, all this is trivial compared with the songs of humpback whales.
The sounds whales make can travel for dozens of miles underwater and you can hear them by finding a very quiet stretch of coast and immersing your head in the water. However, that “very quiet” coastline may be hard to come by, what with beachgoers, surfers and the sound of the waves themselves. So the way to listen to humpback whales is on a boat.
The crew of a well-equipped whale watch boat will at some point turn off the engine and lower a hydrophone – essentially a waterproof microphone – into the water. It senses sounds made by humpback whales which are then amplified and played over the boat’s loudspeaker system to the astonishment of the passengers. And astonishment is the right word, because the whales sound like a cacophonous barnyard with mooing, grunting, squealing and grumbling, plus sounds like the chat-chat-chatter of birds. A hydrophone dropped anywhere in the ’Au’au Channel produces such a variety of sounds that you might not imagine them coming from any single species of animal.
And this “singing” by humpback whales highlights additional mysteries of these impressive creatures: we don’t understand exactly how humpback whales make such an amazing range of sounds, nor do we understand what they are communicating to one another. The best guesses we poorly-informed humans have are that humpback whales make sounds by shifting air between various air cavities in their respiratory system; and that their communications assist the whales in sexual selection.
Have you seen humpback whales in person? What activities did you observe?
Drawing Credit: Photos by Art Chester from Pacific Whale Foundation’s Ocean Discovery, February 19, 2014