Holly N. Ellman

Animal Life, NSC 1307

Spring 2002

The humpback whale is an endangered species, whose numbers have been greatly reduced due to commercial whaling. The whales are in Class Mammalia, Order Cetacea, Suborder Mysticeti, Family Balaenopteridae, Genus Megaptera and Species Megaptera novaeangliae.

The humpback whale is found in all the oceans of the worlds, and most populations follow a regular migration route, such as the population studied in the reviewed article who summer in the North Pacific and winter in the waters of Hawaii. In both locations, the whales can be seen by tourists on whale-watching boats. The whales swim close to shore and leap out of the water (called breaching), although scientists still don’t know the reason for this behavior.

The humpback whale is a baleen whale, with a broad, round body and flat, wide head, which leads to a narrow tail. An adult male averages about 40 to 48 feet in length and weighs around 25 tons. Female adults are larger, averaging 45 to 50 feet and 35 tons. The upper body of the whale is black or blue-back.

An interesting fact is that every humpback whale’s dorsal fin and fluke has a unique color pattern and shape, just as every human has a unique fingerprint. This enables researchers to identify, catalogue and monitor the whales with photo-identification. Using photo-ID, researchers can study the size of populations and their migration, sexual and behavioral patterns.

Humpback whales feed on krill, which are small crustaceans, and several types of small fish. They are seasonal feeders, storing body fat reserves in the summer in their northern habitat, then migrating to warmer, tropical locations such as Hawaii in the winter breeding season.

The investigators studying reproduction included Adam Pack, assistant director of the Kewalo Basin Marine Mammal Laboratory of the University of Hawaii; Lou Herman, director of the Kewalo lab; Mark Deakos, Alison Craig and Scott Spitz, all graduate student researchers at the Kewalo lab; and John Calambokidis, a researcher at Cascadia Research. The investigators studying cooperative feeding were from the Alaska-British Columbia Whale Foundation (unidentified by name) and Kate Sardi, assistant director of the Whale Center of New England. The investigators studying singing whales were Peter Tyack, senior scientist at Woods Hole Oceanographic Institution; unidentified engineers at the University of Massachusetts-Dartmouth; and unidentified researchers at the Australian Marine Mammal Research Center.

Of all the species of whales, the humpback is one that has been the subject of a great deal of research. However, there are still many riddles about their mating and social behavior. No researcher has ever seen a humpback whale mate. Researchers believe that mating may occur nocturnally or in water too deep for observation. Others believe they don’t mate in Hawaii at all, but may possibly do so while on their journey from the waters of the North Pacific. Researchers also wondered about the behavior of male whales. While mating, they were fierce competitors that frequently came to blows; however, on feeding grounds, they became close allies. The Australian researchers wondered why two males were singing a different song than the other 80 singers who were recorded off the east coast of Australia. Several years later, the new song, initially sung only by the two whales, was the only tune heard.

The researchers used videotape recordings and scientific observation to collect the data. The researchers from the Kewalo Basin Marine Mammal Laboratory videotaped mating rituals and other whale behavior. The videotaped images were used to determine the size of the whales studied by entering the videotaped measurement and the distance from the camera to the animal into a computer, which then calculated the actual length of the animal. Videotape also was used to determine when (and therefore, approximately where) the humpback whales mate. By measuring the calves at different times during the winter season in Hawaii, they were able to calculate the estimated time of their birth. Subtracting the gestation period, they could determine when the calves were conceived, which was approximately two months before most of the whales arrived in Hawaiian waters.

From research begun in 1975 by Lou Herman of the Kewalo Lab, researchers have discovered that humpback whales are not placid creatures as they had thought. Indeed, there is fierce competition by males for the rights to mate with the most popular female whales. Researchers discovered that, similar to many other species, size is an advantage for the male whales, with the largest winning most of the battles for the affections of the female. These large males also prefer to court the largest of the females. Additionally, they discovered that "44 percent of the males in the competitive groups" were sexually immature whales that were merely watching the proceedings, learning the behavior that would be needed to succeed when they came of age.

Researchers studying cooperative feeding behaviors among the humpbacks discovered that not only do they exhibit cooperative behavior, they also use a method of feeding that can be characterized as tool use. Another feeding behavior called "lobtail feeding," first observed in 1981, had been adopted by almost 50 percent of the whale population in the Gulf of Maine eight years later. A significant number of the calves in that population also exhibited lobtailing, which indicates that they are "learning it from other members of the population." The researchers believe this behavior has been culturally transmitted.

Scientists studying the vocal whales believe the singing is a factor in the breeding behavior of male whales. The behavior has been likened to the singing of male birds, which use it as a "reproductive advertising display." Engineers studying the songs have discovered what they believe to be a complex organizational structure, although it is not necessarily thought to indicate a language per se. Peter Tyack (Woods Hole Oceanographic Institution) thinks this reflects more of an element of style, rather than language.

This article did a good job of communicating information about the humpback whale, a fascinating creature. Evolved from an ancestor that also contributed deer and sheep to the animal kingdom, this whale is a mysterious creature.

I was surprised to learn that prior to 1975, the whales’ migration route from the North Pacific to Hawaii was unknown. When a tourist goes to Hawaii today, they have numerous opportunities to go whale watching.

The humpback whale had been considered by many to be a "gentle giant;" however, this was a fallacy. Males combat fiercely for the rights to court a female, sometimes to the point of death. An interesting sidebar is that the winning males prefer the largest of the females – totally opposite in most cases to the human population!

Another fact I found interesting was the daunting task the new mother has – during the period when she is fasting and losing half her body weight, she must produce an enormous amount of milk for her calf. This would be impossible for the human mother, who must consume more calories than normal while she is breastfeeding.

The fact that the whales work together to trap food, especially after having come to blows just a short time before while mating, is curious. Most animals that I am aware of tend to adopt more of a "survival of the fittest" attitude – although they may not contribute to another animal’s misfortune, I am unaware of any other species that assists each other such as the humpback whale.

The singing of the whales is also very interesting. I thought it was telling that the smaller males were the ones who tended to sing. It brings to mind the human behavior of smaller men who try to compensate with humor – Billy Crystal, Danny DeVito.

The good news is that there are many researchers out there working to unravel the mysteries of the humpback whales, and that there will be more intriguing discoveries to come.

Michael Tennesen; "Tuning In to Humpback Whales;" National Wildlife, February/March 2002; Volume 40, Number 2; pages 14-23.

American Cetacean Society, American Cetacean Society Fact Sheet HUMPBACK WHALE, http://www.acsonline.org/fackpack/humpback.htm.

Alaska Department of Fish & Game, Humpback Whale, http://www.state.ak.us/local/akpages/FISH.GAME/wildlife/geninfo/game.