Behavior

Killer Whales

Behavior

Behavior Observation

  1. For the most part, killer whales in the wild are visible only when they are at the surface, so it is inherently challenging to document and study whale behavior.
  2. Possibly the most-studied killer whales in the wild are the resident killer whale communities of the eastern North Pacific Ocean.
    • Much of what we know about killer whales comes from studying these whales.
    • Ecotypes of killer whales can be very different from one another in diet, appearance, dialect, and genetics. Experts use caution when generalizing about killer whales, knowing that the different ecotypes of killer whales that have not been as well studied may be quite different from the eastern North Pacific resident whales.

Social Structure

  1. Killer whales live in cohesive long-term social units called pods. A pod is a group of individuals that travel together the majority of the time. A pod is a group of related matrilines that probably shared a recent maternal ancestor. Pods are less stable and it’s not unusual for a subpod to break away from the pod for an extended period of time.
    • Pod size can vary tremendously. In the eastern North Pacific Ocean, pod size varies from just­ two or three to more than 100 individuals. In general, resident pods are larger than transient pods.
      • Resident pods usually include between five and 50 whales.
      • Transient pods usually include only seven whales or less. In fact, some transient “pods” consist of a solitary adult male. Rarely, transient pods come together to form groups of 12 or more. More than 30 individuals were spotted in a transient killer whale pod in the western Okhotsk Sea.
      • Offshore killer whales are sighted in groups of less than 20 to more than 100 individuals.
      • Off Alaska and Antarctica, groups of more than 100 animals have been observed. Larger groups of 130 to 500 individuals have also been seen, with one report of a gathering of an estimated 2,500 individuals. These larger groups may be due to seasonal prey aggregations, for social interaction, or for mating.
      • Scientists theorize that these differences in pod size are related to the whales’ feeding habits. A large pod size may be best for herding and hunting schools of fish, and a small pod may be best for hunting marine mammals.
    • A subpod contains generally one or more matrilineal groups that typically always travel together. Sometimes a subpod will temporarily break away from its pod.
    • The most fundamental social unit in a pod is a matrilineal group, which may include two or three generations of whales. A two-generation matrilineal group consists of a female whale and her offspring. A three-generation matrilineal group also includes her “grandchildren,” the offspring of her female offspring. Individuals in a matrilineal group travel closely together.
    • In the North Pacific, the largest matriline of resident killer whales recorded to travel together consisted of five generations.
    • Killer whales live in social groups called pods.

  2. A clan is a social level above the pod level. Clans are made up of pods in an area with similar dialects and are thought to be related. These pods may have developed from one ancestral pod that grew and fragmented over time. Pods from different clans are frequently seen traveling together.
  3. A community is a group of killer whales that share a common range and associate with one another.
    • There may be several pods within a community.
    • Along the coastal waters of British Columbia, Washington and Alaska, three communities of residents have been documented.
    • Pods from one community have rarely or never been observed traveling with those of another, even when their ranges overlap.
    • Occasionally there is an exchange of pods members, such as for breeding purposes.
  4. A pod is a group of individuals that travel
    together the majority of the time.

  5. Off Alaska and Antarctica, groups of more than 100 animals have been observed. Larger groups of 130 to 500 individuals have also been seen, with one report of a gathering of some 2,500 individuals. Researchers are uncertain why killer whales form such large groups at times.

Social Behavior

  1. Killer whales in a pod establish strong social bonds. Observers note that certain individuals are regularly seen associating with one another.
  2. The strongest association bonds in a pod are the mother/calf bonds.
    • A mother killer whale stays close to her newborn calf and attentively directs its movements.
    • The mother/calf bond weakens as a young killer whale matures, but for resident whales of the eastern North Pacific, it lasts throughout adulthood. In fact, these resident killer whales societies are unique in that a juvenile killer whale does not leave its mother or disperse from its maternal pod when it matures.
    • In transient pods of the eastern North Pacific Ocean, a whale may leave its mother to travel alone or with other whales.

    The killer whale social hierarchy is matriarchal or female-dominant.

  3. As with many species, a social hierarchy exists within a group of killer whales. The hierarchy is female-dominant.
    • Killer whales within a pod may rank themselves and establish dominance by slapping their tails against the water, head-butting, jaw-snapping, biting, raking (tooth-scratching), and various other vigorous postures and gestures.
    • SeaWorld observers noted that calves receive social discipline from their mothers and other significant adults. Discipline may be in the form of restraining (corralling the calf thus restricting its movements) or raking (tooth scratching).
    • Tooth scratches can leave a killer whale with scars, but generally
      these scratches are superficial.

  4. Killer whales often hunt together. (See Diet: Food Preferences & Resources and Diet: Methods of Collecting Food)
  5. Interactions between resident and transient pods have not been observed. When they are traveling in the same area, they most often appear to ignore each other. At other times, transient whales actively avoid resident whales.

Individual Behavior

  1. Whale watchers and researchers have named certain common whale behaviors.
    • A breach is a behavior in which a whale powerfully thrusts a large part of its body out of the water and lands on the surface - usually on its side or on its back - with a huge splash. Sometimes the same whale will breach several times in sequence.
    • A spyhop is a behavior in which a whale rises out of the water somewhat vertically, exposing its head.
    • Lob-tailing (slapping the tail flukes on the surface of the water), dorsal fin slapping (rolling onto one side to slap the fin on the surface of the water), and pec-slapping (slapping a pectoral flipper on the surface of the water) create loud sounds above water and under water.
    • A spyhop is when a killer whale hangs vertically
      in the water with its head partially above water.

  2. Killer whales in the Johnstone Strait in British Columbia rub their bodies along the pebbly bottoms of shallow bays (sometimes called “rubbing beaches.”) They may do this to help remove sloughing off skin.
  3. Behavioral studies suggest that killer whales “play” with and manipulate objects.

Stranding

  1. A killer whale may strand if it is affected by a severe, debilitating illness or injury, or if it is too weak to swim or hunt for food. (See Longevity and Causes of Death.)
  2. In some areas, killer whales temporarily slide up onto ice or sand to pursue prey. This behavior is not considered stranding.

Interaction with other Marine Mammals

  1. Killer whales prey on many species of marine mammals. (See Diet.)
  2. Killer whales have also been observed harassing other marine mammals, without eating them.
  3. At other times, killer whales have been seen feeding in the same area with other marine mammals, with no apparent reaction by the killer whales. Some species, including those that are known prey for killer whales (minke whales, Dall's porpoises, and seals, for example) have been observed swimming with killer whales.
  4. Other marine mammals may flee or avoid killer whales, but at times they seem to ignore them. Sometimes other marine mammals appear to be attracted to killer whales.