Migrating Naturalist: Aquatic Melodies

Every once in a while someone in our research group gets kicked off the boat. Not due to bad behaviour, but simply because there are too many volunteers offering help. Our research vessel Deep Blue holds only 6 people, and so on days when underwater divers are on board, an equal number of interns must remain behind. Most of the day is spent entering data and editing fluke ID images, but if you budget time well, there is always a chance for adventures. Today I caught a ride with Michelle (a fellow intern, from Alaska) and her dog Vista, to North Ka’anapali for a snorkeling trip.

As soon I dove headfirst into the crystal blue water, an underwater symphony met my ears. An untold number of whales were singing, creating the world’s most unique chorus. The beaches North of Lahaina are ideal for acoustics, as they lie alongside the ‘Au’Au channel, the sheltered area in which many humpbacks reside. Because of this, the songs of even faraway whales can be heard with remarkable clarity.

Singing is one of the most intriguing of humpback behaviours, and is possibly their greatest mystery. Although these songs have been extensively studied, and much has been revealed, researchers still have not discovered why the humpback sings.  We do know that only males sing, which leads many to believe that the behaviour is related to mating. However, some studies have revealed that when one male sings, other males will actually move into his area, so it may be for a completely different purpose. The term “song” is used loosely, as these vocalizations will consist of a string of curious noises that resemble humming, snoring, groaning, sighing or chirping. I have even heard one that sounded exactly like a California Sea Lion barking! The way that males sing is also fascinating, as a male will dive down about 50 feet and hang motionless, suspended head-down, singing for up to 30 minutes. One of the most baffling facts is that as the season progresses, the songs will change slightly, with all the males in a population altering their tune around the same time. Worldwide researchers in a cooperative study found that just days after the Hawaii whales “changed key”, the rest of the North Pacific population (in Mexico and Japan) made the exact same shift. What exactly this means is not yet known, but it creates the initiative for many future studies on this mystifying behaviour.

My name is Diana, and for the past two years, I have been travelling between my naturalist position in Tofino with West Coast Aquatic Safaris, and my research intern position with the Hawaii Whale Research Foundation. Throughout my second season with HWRF, I am writing regular blogs, describing my experiences on the water and here in Maui.

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