Humpback whales were given this common name because of the shape of their dorsal fin and how they arch their back as they dive; this motion emphasizes the hump before the dorsal.
The scientific name, Megaptera, means "large winged" and refers to their long, white, wing like pectorals which may be as long as one third of the whale's body length.
Each whale has a unique pattern on the underside of its tail fluke, which can be used as a fingerprint for researchers to identify individual whales. Humpback whales can live up to 70 years of age, the average being approximately 50. The females are larger than the males, and can measure from 45 to 50 feet (13.7-15.2m). A male measures from 40 to 48 feet (12.2 to 14.6m) They can weigh from 25 to 45 tons ( 22,680 to 36,287 kg). They reach sexual maturity at 6-8 years of age. A female may give birth once every 2 to 3 years, the gestation period being 12 months. A calf will nurse from 8-11 months of age and, once weaned, they are 24 to 27 feet in length. They will leave this mother-calf bond generally following the next spring migration to feeding grounds.
Humpback whales are found in all oceans. They all follow the same migrational pattern from summer feeding grounds to warmer waters in the winter for calving and possible breeding. The population that we observe along the north coast of British Columbia winter in Hawaii and start to arrive back in our research area by June. For many the final destination is Alaska's Glacier Bay and the Bering Strait. From July till the end of November we are in the presence of these unique mammals.
Quite often we will observe one humpback whale following the shoreline with the intense purpose of feeding. Every 200 to 300 meters the whale will take a few shallow breaths, then arch its back to prepare for a deep dive. Our last sight is that of the tail fluke. Often others will join this whale and they will cooperate in an intriguing feeding strategy referred to as Bubble Net Feeding. The whales will dive below a shoal of prey, approximately 50 meters, and then slowly they begin a spiral dance towards the surface, blowing bubbles in a circular motion. On the surface you will actually see a circle of bubbles form as the whales move in this spiral formation. The purpose of the bubbles is to congregate prey and force them towards the surface near the center of this circle. What you will witness next is an explosion of air as these whales surface in the center of this circle of bubbles, their mouths gaping wide open. Humpback whales have 14 to 35 throat groves that run from chin to navel. These grooves facilitate the throat to expand. This expansion allows for large volumes of water and food into the mouth. As the mouth closes the whale will press down with its tongue forcing all water out through baleen plates. These baleen plates hang in row from each side of the upper jaw. Baleen is made of a similar protein to the human fingernail; they are very strong and flexible.
Another method of feeding we often see with whales feeding alone is "Lunge Feeding". The whale will lunge through a shoal of prey with mouth gaping open often exploding at the surface with both food and water.
Humpback whales do not feed in the warmer climates of Hawaii and Mexico so it certainly makes sense that once they arrive in their feeding grounds, this will occupy most of their time. They will feed on krill and various kinds of small, shoaling fish such as herring and mackerel. They may eat up to 1,400 kg of food a day.
While humpback whales feed, especially when it is a group effort, there will be an array of different calls from short grunts to long hollow calls.
Many days a mother and her calf will slowly make their way into the bay in which we live. They may spend the entire day just floating on the surface, side-by-side, resting from their long journey. From time to time they will take few shallow dives, then once again remaining motionless. As they rest you are aware of their presence only from their distinctive blow. Humpback whales have two blowholes. As they breathe, two columns of vapor form a heart shaped plume up to 3 meters high.
The Humpback Whale Song
One of the most complex songs in the animal kingdom is that of the Humpback Whale. The complexity lies in the structure of the song. A song may contain up to 30 different sounds and may last from 15 minutes to 30 minutes and some up to one hour. The humpback whale song varies geographically. For instance all humpback whales within the North Pacific will sing the same song but this song will be very different from the humpback whales of the North Atlantic Ocean. What is most remarkable is that whales in a particular area that sing the same song will over time change this song. A song that may have been recorded 5 years ago would be radically different today in terms of content. All the whales will now sing this new song. This song is thought to be a male breeding display to attract females, to sort dominance among males or to maintain a distance between courting whales. These for now are theories though it has become quite evident that only the male humpback whale sings. Perhaps this change in a song occurs when a male makes a slight variation to a song, which appears to attract females. Other male whales in the area pick up this variation. Over time, these variations will eventually lead to an entirely different song. When a male humpback sings they will float, suspended in water fairly deep with head down, relatively motionless. This positioning of head down allows for the maximum propagation of produced sound.
As fall approaches, and the days become shorter and colder, we begin to notice a change in the behavior and interaction among humpbacks whales. During the summer months they display remarkable gentleness and cooperation. Perhaps the hormonal change that may spur them to travel south to warmer breeding grounds has occurred and the urgency of sexual competition is settling in. We will see groups of 3 to 5 whales, lunging through the water together, almost porpoising their giant bodies out of the water. Then a sudden dive by all. When they surface, their entire bodies are almost on top of one another. They will travel very fast during this time as if a specific destination is intended.
It has long been believed that humpback whales will only sing in the warmer waters where breeding and calving occurs. In recent years this belief has been challenged as more and more researchers along the coast of BC and Alaska have deployed hydrophones. To our delight, in the early weeks of October we recorded our first ever humpback whale song. This song lasted over 30 minutes and there were many more to follow. This singing behavior has so far only been documented to occur in the fall months just before the whales begin their long migration south. We will be curious to see if some humpback whales will spend the entire winter season here and not participate in the migration south for age related reasons. Listening the song of a humpback whale or the vocal activity of a family of orcas is truly inspiring. Please be sure to listen to the examples Cetacealab has to share with you on this site.