Well known for their acrobatic surface displays, humpback whales are a favorite for whale watchers around the world. The meaning behind these impressive behaviors, however, is still unclear. Because many of the behaviors are performed by both males and females, and on both the winter breeding grounds and summer feeding grounds, researchers believe that the interpretation of these behaviors may largely depend upon the context in which the behavior is observed.
On the breeding grounds, males engage in three primary behavior patterns, including singing, associations with other males, which include both non-agonistic and agonistic behaviors, and escorting, guarding or defending females. Much less is known about female behavior patterns on the breeding grounds, but females are generally involved in courtship and mating and/or activities associated with the care and protection of newborn calves.
The Humpback Whale is a baleen whale with vertical throat grooves which allow it to glide along collecting food into its mouth. There are 10 species of baleen whales. Baleen whales are larger than the toothed whales.
Whale watching requires patience, as whales spend most of their lives out of our field of vision. Usually, the only reason whales come to the surface is to breathe. The average down time or dive time for humpbacks is between 5 and 15 minutes in length (3-5 minutes for calves.) Humpbacks are capable of holding their breath for 45 minutes or longer, however, dives of this length are unusual.
Whales have very efficient lungs. Humans exchange only 15% to 20% of the air within our lungs with each breath we take. Whales on the other hand, exchange over 90% of the air in their lungs with every breath. The size of a humpback's lungs also assist its breathing capacity. Its lungs are the size of a compact car!
Humpback whales also have a substance in their bloodstream called myohemoglobin. Myohemoglobin aids in holding oxygen, then delivers it to whatever part of the body needs it the most. They also have an oxygen holding substance in their muscle tissue called myoglobin. In fact, whale muscle tissue is a deep red, almost purple color because it holds such an amazing amount of oxygen.
There are two major groups of whales. There are the Odontocetes or toothed whales and the Mysticetes or baleen whales. Humpback whales are baleen whales, which do not have teeth. Instead they have what are called baleen plates.
Baleen plates are made up of a protein substance called keratin, which also makes up human hair and fingernails. In a humpback whale there are approximately 335 baleen plates, about 2 to 2 ½ feet in length. These baleen plates hang vertically from the whales upper jaw. The whales filter their food, straining water out through their baleen using their tongues. This allows the whale to take in between 500 and 1000 gallons of water and hopefully, 40 to 50lbs. of food in one mouthful. Although the humpback whale is only capable of swallowing something slightly smaller than a grapefruit, it can still consume approximately one ton of food per day.
Hawaiian waters are so clear and blue because they lack phytoplankton. Phytoplankton are tiny, microscopic plants that bait fish feed upon. Because of this, there are very few bait fish in Hawaii.
Essentially, the whales are fasting in Hawaii for 4 to 6 months. They live off of their blubber/fat layer and as a result they can lose up to 1/3 of their body weight. The average weight loss is about 25%, or 6 to 8 tons.
The only whales getting a decent meal are the calves. Imagine the strain put upon the nursing mothers!
Humpback whales are solitary animals. Contrary to popular belief, humpback whales are not monogamous, they do not mate for life. Although humpback whale mating has never been documented, they are thought to be promiscuous breeders. Scientists never really know which male has fathered which calf. The males play no parental role that we know of.
Genetic testing shows that over several years the various calves from an individual mother will have different fathers.
Humpback whales don't appear to make lifelong bonds either. Instead, they have what are called "associations". Whales are considered to be associated if they are surfacing at the same time, diving at the same time, engaging similar behaviors, and if they are traveling within a body length of each other. These associations are usually brief. They can last anywhere from a few minutes, to a few days. Of course, there is one exception to that rule.
The mother and calf pair are the exception to the other brief whale associations. The mother generally never lets her calf stray more than a body length away for very long. They spend the first year or so of the calf's life together. The calf learns valuable survival lessons in this short amount of time, and is then weaned and separated.
A competitive pod forms when one female is pursued by a large number of males. These males are fighting amongst each other, perhaps to "impress" the female. The competition can become extremely aggressive, even resulting in blood shed.
Male whales will literally head slap, and tail slap each other. Some even breach right on top of another male.
Competitive pods are usually fast moving, with the female in the front. She can travel in a straight line or change directions as often as she pleases, as the males will generally follow the female wherever she decides to go.
The male closest to the female is called the "primary escort". We believe this is the best spot for eventually being chosen by the female for mating. The other males in the pod are called "secondary escorts" or "challengers". The secondary escorts seem to be be competing for the primary escort's position.
The gestation period for a humpback for a humpback whale is 11-12 months. When a baby humpback is born it is 12-14 feet in length and weight 1 to 1 ½ tons.
During the first six months of a calf's life it goes through an amazing growth spurt. It will grow about an inch and gain about 100 pounds each day. The reason for the growth spurt is because the calf is living entirely off of mother's milk. Humpback whale milk is some of the richest milk in the world. It is close to 50% fat, and has the consistency of cottage cheese.
The calf nurses by suckling on the mother's single teat, squirting the milk right into its mouth. This way very little milk is lost or dissipated in the water. A calf will consume around 50 to 100 gallons per day. It has to gain strength and body size before making the long swim to Alaska.
One of the greatest mysteries of the animal kingdom is the whale song. Yes, male humpback whales do the singing here in the breeding grounds. This leads researchers to believe that it is either an attempt to attract females or to ward off other males.
Singers are usually lone animals, staying in one spot. They sing about 50-60 feet below the surface, for about 20-40 minutes, with their heads pointed downwards and their tails pointed upwards. The song has a very complex structure, similar to a classical music piece. It can be broken down into units, phrases and themes, which make up the entire song.
Even more amazing, is that on any given day, all of the male humpbacks in Hawaii will be singing the exact same song, even though the song changes as the season progresses. This years' song will start off where last years' song ended, which provides evidence for an amazing memory capacity considering the whales only sing these songs in their breeding areas
As the season progresses the song will gradually change. New pieces will be added and others will be dropped. One whale may carry a note a bit longer than another whale, but the structure and components are the same.
This phenomenon extends beyond the whales here in Hawaii. It includes the whales that are part of this population that migrate to Japan and to Baja. Scientists are not sure how this is possible, as it insinuates long distance communication, other thousands of miles. One possible explanation is the theory that humpbacks visit different breeding grounds in one season. The song could be passed on by these travelers.
We don't know if the whale's song is a language in our sense of the word. It could be used as a display to show the females which male is the strongest or most genetically fit, by showing how long, or loud they can sing, how long they can hold their breaths, etc. Smaller whales may be trying to attract females by singing since they are too small to compete physically with larger males. And recent research is revealing that mostly males approach singing males.
The males generally space themselves about ½ mile away from other singers, which may imply territoriality. The song lasts 15-18 minutes and is then repeated. Since Katy and Roger Payne first scientifically described and identified the whale song in 1979 here in Hawaii, the song has never repeated itself, and is continually evolving. The whale song is also unique to each population so the North Atlantic whales sing a completely different song than the whales here.
Humpbacks do not have vocal cords and no air is being emitted from their bodies while they are singing. So how do they make this eerie yet beautiful song? Researchers believe humpbacks make the song by moving air through valves and sacks in their respiratory system, similar to taking the end of an inflated balloon and slowly squeezing the air through it.
© Copyright 2015 - Hawaii Ocean Project
Lahaina Harbor, Loading Dock Main Booth, 675 Wharf Street, Lahaina, Hawaii 96761