Because whales spend most of their lifetime beneath the waves where they are not easily observed, their behavior is difficult to study. Furthermore, the snippets of behavior that occur at the ocean's surface may not be representative of the animals' behavior below and are not always easy to interpret. To further complicate the picture, various subgroups of a large group of resident whales spread out across a passage may be involved in different behaviors at the same moment. For example, a group of juveniles may be playing while another trio of adults is resting half a mile away. At present, the critical examination of whale behavior is still in its infancy.
Based on observation, broad categories of behavior have been identified. Major behavioral categories include traveling, foraging and feeding, resting (group resting and individual resting), and social interaction/play. These are general categories used for many animal behavior studies. Although resident and transient whales share many of these behaviors, there are significant differences between the two types. Eva Saulitis is presently taking a closer look at some of the behaviors peculiar to transient whales.
Both resident and transient killer whales are constantly on the move. The fabric of their lives is woven with the thread of constant motion. Even during resting, there is often some degree of stead movement. With an average speed of about three knots, they may cover considerable distances during a twenty-four hour period. At times, whales move back and forth through the same areas for several days. Thus, whale researchers must distinguish this behavior from true "traveling behavior" where the basic activity is moving from point A to point B. In true traveling, no feeding, social activity or resting are observed. During slow travel the whales swim only two to three knots. However, during spurts of rapid travel, they have been clocked at eight to ten knots. Typically, a traveling resident whale will breathe three or four times, while moving along at the surface and then make a three to five minute dive. After the last breath, the whale makes a slight arch of the back and tail stock as it begins to sound. The whale moves faster while submerged and will resurface to repeat the same breathing and diving pattern. Transients make dives as long as ten minutes while traveling. Traveling occupies over thirty percent of their time while this figure seems to be much less for resident whales. In the Sound transients may have to travel great distances to find prey (porpoise and seals) scattered over a wide area.
Killer whales traveling in small groups afford the best opportunity for obtaining identification photographs. On one occasion we followed AB pod as it steadily crossed the Sound, traveling over forty-five nautical miles in ten hours. On another occasion, AK pod was photographed near Fairmont Island then photographed again twenty-three hours later near Chenega point - 42 miles to the southwest.
Occasionally, transient whales have been observed swimming at great sped. Often this occurs when whales are about to join another group. We have clocked them porpoising along at the surface at 16 knots for short periods. Shooting alongside a formation of speed swimming killer whales in a small skiff, one is mesmerized by the full extent of their strength and power. Their blows explode as they break the surface, and the spray flies as their bulk hurtles forward, half their body breaking free of the water.
Often young whales will swing into ride on our stern wake, speed swimming in toward the skiff or boat and then surfing along in the rapidly foaming wake. (see photograph on cover of the book). Once a nearly thirty foot long adult male actually swung alongside the thirty-six foot research vessel and swam along in the bow wake for a short period. These behaviors serve as reminders that the killer whale is really a very large dolphin.
Killer whales cannot settle down for a good night's sleep as we do. Their breathing, unlike ours, is voluntary which means they must consciously rise to the surface to breathe. Resting seems to be a ritualized pod activity. Often whales in a pod will synchronize movements and breathing patterns when they slow their activities to a rest. When "group resting," all or part of a pod assemble into a tight unit. Movements are slow with a series of up to ten breaths taken before the animals arch and submerge for four to ten minutes. The whales keep moving slowly, sometimes back and forth in the same area. As resting deepens, the movements of the whales become slower, and the time they spend submerged increases. There is little vocalization other than distinct and infrequent resting calls. During group resting, the whales may shun interaction with vessels. If approached, they tend to circle away from the boat.
During group resting, whales frequently line up in their maternal groups. The relationships between the individuals are clearly defined. A mother and her offspring often rest shoulder to shoulder with the youngest offspring closest to the mother. Even the order in which the whales surface appears to be highly ritualized.
Occasionally, more than one pod rests together. Once, we observed more than seventy whales (AN and AJ pods) stretching in a line, shoulder to shoulder, resting in a single group. Their dorsal fins were lined up like pickets in a fence as the whales surfaced together. Group resting may continue for three or four hours, although usually it occurs for shorter periods.
Often the calves do not seem as interested in resting as the adults and will continue to play as the others begin to rest. On one occasion, a frolicking calf rolled repeatedly over its mother's back while the pod moved slowly. The vocalizations of the calf continued as the other whales fell silent. Suddenly, there was a sharp call and a slap of the mother's flukes. The calf made a noise like a squealing pig and darted off. Then, quietly it returned and lined up alongside its mother.
Group resting occupies a significant percentage of the whales' time (probably over ten percent). This indicates the importance of this activity. It may be a time when social bonds are strengthened as indicated by the ritualized nature of the activity.
"Individual resting" more closely resembles sleep in humans, although it hardly seems more than a catnap by our standards. When resting individually, a whale hangs motionless in the water with the blowhole and dorsal fin exposed. It may remain motionless for one to three minutes before rising slightly and breathing. Finally, as it begins to sink below the surface, the whale wakes and either resumes its resting position or begins to move along in the water again. Individual resting may involve a single whale or a small group of whales. It is the only time that these whales seem to stop moving.
Whales in the AT1 transient group mostly rest individually and have only
been seen group resting on rare occasions. However, Eva once watched transients
group resting for over seven hours in Dangerous Passage, behind Chenega