- 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.
- 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.
- 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.
- 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.
- 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.
A pod is a group of individuals that travel
together the majority of the time.
- 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.
- Killer whales in a pod establish strong social bonds. Observers note that certain individuals are regularly seen associating with one another.
- 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.
- 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.
- Killer whales often hunt together. (See Diet: Food Preferences & Resources and Diet: Methods of Collecting Food)
- 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.
- Whale watchers and researchers have named certain common whale behaviors.
- 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.
- Behavioral studies suggest that killer whales “play” with and manipulate objects.
- 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.)
- 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
- Killer whales prey on many species of marine mammals. (See Diet.)
- Killer whales have also been observed harassing other marine mammals, without eating them.
- 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.
- 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.