Learn About Orcas

What are orcas?

Orcinus Orca is one of the most widely-distributed marine mammals in the world, and is the world’s largest species of dolphin. They are known as Orcas, Killer Whales or – off the west coast of North America – Blackfish. They are found in all of the world’s major oceans, covering all latitudes, and inhabit both coastal waters and open oceans.

Each population of orcas, while similar in appearance, has vastly different habits. Some eat only fish, others marine mammals; some eat both. There have even been documented attacks on rays (New Zealand) and Great White Sharks (South Africa)!

In the Pacific Northwest, we see three distinct ecotypes of orca: Residents, Bigg’s (transients) and Offshore.

The Resident orca populations are further split into Northern and Southern Residents and their range extends from Washington State up to southeast Alaska. These two resident communities, despite their close geographic proximity, have never been observed to mix with each other. Their fish-only diet contains predominantly salmon, although they have been observed eating other fish species, too.

Bigg’s orcas (named after Michael Bigg) can cover huge distances from Alaska down to California. They predate on marine mammals and hunt silently. The Offshore population is much more elusive, only seen in inland coastal waters infrequently. Studies suggest they are fish eaters, feeding perhaps on sharks.

Orca Communication

Communication lies at the core of orca social awareness. Family members are seldom out of hearing range of one another, and their calls echo over many miles in the ocean.

Orcas make three types of vocalizations: clicks, whistles, and calls. The clicks are part of the whale’s sonar and are used for echlolocation: for finding and locating food sources, for defining other objects in the ocean, and for locating the whale in its environment. Whistles are typically continuous tone emissions that may last for many seconds. Calls are discrete pulses that are unique to each family of orcas.

Orca calls

These pulsed signals have patterns that can be recognized by ear and by spectrogram. They are the most useful acoustic tool that we have for identifying individual matrilines (families) of orcas. Dr. John Ford categorized the discrete call types for the orcas of Washington State and British Columbia in the 1970s. He discovered that each pod has its own collection of calls which he referred to as their dialect. He was then able to define larger acoustic clans by grouping together pods that share common calls. Only pods that share common calls are part of that clan.

The role of these calls is not precisely known. However, the different calls are certainly a way for the whales to keep track of each other over large distances, in the dark, or when large congregations occur. Though it has not been demonstrated, there is certainly potential for the communication of complex, specific information in calls. Sometimes groups are very vocal and at other times the groups may be silent.

Listen to the differences in sound between Resident and Bigg’s orcas.

Northern Resident orca calls

Bigg’s orca calls

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Fact File: Northern Resident Orcas

Our lab is situated in the historic summer home of many of the Northern Resident population, and we have spent five decades getting to know them.

Diet: Fish (primarily salmon)

Population size: 310 (as of 2022)

Range: Southeast Alaska to Northern Washington

Interesting behaviours: Rubbing on rocks at smooth, shallow beaches, sometimes for hours at a time.

Social organization

The Northern and Southern Resident Orca Communities of the Pacific Northwest have over 400 individuals. Within those communities, they live in small nuclear and extended families that we call matrilines, pods, and clans.


At the social heart is the orca mother. She and her children, even her adult sons, stay together throughout life. It is common to see several generations travelling together as a group. Adult daughters with their own offspring may separate from their mothers to some extent to take care of their children’s needs, but they will usually be found travelling nearby. Acoustic and cultural traditions are passed on from mother to offspring, resulting in generations of learned behaviour and tradition.


Beyond the central maternal groups, pods are extended families of closely related mothers and their families. A pod can be defined as those orcas that are usually seen travelling together. For Resident orcas, a pod may number from around 5 to 50 individuals. Resident orcas are such social beings, and it is not unusual to see large numbers of matrilines and pods come together and share the same area. The Northern Residents have 16 pods, whereas the Southern Residents have just three.


Orca clans are defined in terms of the acoustic traditions of pods within an orca community. Pods that share common calls belong to the same clan. Separate clans do not share calls. In the Northern Resident Community, there are 3 clans: A, G and R. There is just one clan in the Southern Resident Community: J. Interestingly, pods from separate clans commonly socialize with each other within the community, even though they do not share calls.

Fact File: Bigg’s Orcas

Bigg’s (also called Transient) orcas are commonly seen in our study area year-round. They are named after leading orca biologist, Michael Bigg.

Diet: Marine mammals (such as sea lions, seals, porpoises, and dolphins)

Population size: Around 400

Range: Alaska to California

Interesting behaviours: Coordinated hunts with very little vocal communication, so as not to alert prey.

What about the Southern Resident orcas?

The Critically Endangered Southern Resident population of orcas has attracted worldwide attention. Learn more about these orcas and the efforts to protect them.

The Southern Resident orcas – made up of J, K & L pods – do not typically pass through our study area, except for perhaps once or twice a year. They more commonly favour the southeast & western sides of Vancouver Island and the Puget Sound. With fewer than 75 individuals left and several stress factors, many communities, NGOs and governments are working tirelessly to recover this population.

Center for Whale Research →

Coextinction Documentary →

Psst, Say Orca!

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