Orca Natural History


The Orca Salmon Alliance’s (OSA) main message this year is that our Southern Resident orcas are in troubled waters. OSA would like to challenge others to think about salmon recovery in terms of the foundation of nutrition the fish give to numerous species and ecosystems of the Northwest, including our beloved fish-eating killer whales, the Southern Residents. For these orcas, lack of their primary prey, Chinook salmon, is leading to a high rate of mortality and miscarriages and changes in their social structure and pod cohesion. As they spread out more to find food they spend more time foraging and less time socializing with one another. It has been just over 10 years that many of the Chinook runs within the Southern Residents’ range were listed under the Endangered Species Act and both Chinook and the Southern Residents’ future still hangs by a thread. While shortage of prey is their primary threat, Southern Resident orcas are also endangered by toxic pollution, from persistent chemicals such as PCBs, DDT, and flame retardants, and noise disturbance from shipping boats in the Salish Sea. OSA aims to raise awareness about these threats to our Southern Resident population this June and will provide calls for action that will make a difference for these iconic Northwest species.

Learn more about whales at the Center For Whale Research or Orca Network.

Want to see orcas? View this Orca Spotting Viewpoints Map.

Killer Whale Natural History

The orca, or killer whale, is a wondrous and impressive creature by any measure. For millions of years there has not been a predator in the sea that can touch Orcinus orca, the largest member of the dolphin family. And yet, there is no recorded case of a free-ranging orca ever harming a human. Even when orca mothers are violently pushed away with sharp poles so their young can be wrestled into nets and loaded onto trucks, they have never attacked a human being. When seen in movies like Free Willy, or doing tricks at marine parks, it is easy to see that they often show extreme responsiveness, even affection toward humans. Having little else to do in captive situations, they often initiate playful interactions and engage in mind games with their keepers.

When encountered in their natural marine environment, however, their behavior is much different, much less interested in human affairs. Though always mindful of boats large and small, they tend to simply continue traveling, foraging or socializing with one another, as though thoroughly engaged in the complex social life of their families. Occasionally, however, some may pass surprisingly close to a boat as if to inspect the passengers as they glide with masterful ease through these vast inland waters.


Like all whales, orcas have brought their breathing under conscious command. They rest by relaxing one hemisphere of their brain while guiding their swimming and breathing with the other half, often while swimming slowly in tight family groups. Orca brains are enormous, over 4 times human brain size with a highly developed and convoluted neocortex, an association area responsible for sophisticated cognitive processes. Consciousness correlates with the degree of complexity in the nervous system, and the structural complexity of the orca brain appears capable of supporting a degree of consciousness that could allow culturally acquired, meaningful communication.


A unique vocal repertoire is used by each orca community. Within communities pods and matrilines make a few of their own distinct calls, known as dialects. Unlike some dolphin species, no “signature whistle” has been found in orcas. Every member of any given pod or matriline uses the same set of calls, and the majority of calls are shared with the whole community. Given that there are significant differences in behavior and in vocal repertoires from community to community, linguistics is highly correlated with group behavior. That indicates the behavior is mediated by the vocalizations, meaning the cultural rules for behavior are probably communicated by vocal expressions. Those rules appear to determine cultural traditions such as diets and mating patterns, and lifetime group cohesion.

Of course orcas need to successfully find food and reproduce, so ecological or energy considerations are crucial. Those requirements are accomplished as a group, through cultural traditions. Sometimes essential problems may not be successfully solved (at least from a human vantage point), as in mass strandings, but it seems to be a decision-making process adhered to by the entire group, with vocalizations playing a key role. Overall, it appears orcas use a communication system we might as well call language.

Culture and Social Behavior

Some of the most interesting questions about orcas concern their social and cultural behaviors. Each community so far studied shows tremendous originality in their habits and social systems. Their diets, feeding strategies, patterns of movement, and of course their communication systems, vary widely between communities. Cetologists are just beginning to look at the differences in cultural adaptations between orca populations, and are coming to the realization that we are dealing with mammals that are capable of culture in the form of traditions and rules of behavior, much like us, and that meaningful communication may guide their behavior. There are probably less than 50 distinct orca communities worldwide, with the total number of individuals only about 30,000, some of which are tentatively classified as either residents (fish-eaters) or transients (mammal-eaters). All orcas travel over fairly large areas, but residents tend to frequent a specific territory and return with some regularity to the same areas. Resident pods usually include ten to twenty individuals and seem to eat only fish. Such generalizations are only preliminary however, and as results emerge from studies of orca communities around the globe new surprises are sure to follow. Until field studies began 40 years ago, very little was known about the lifestyles or abilities of these powerful and elusive animals. As a species, orcas have the widest global range of any mammal except humans and may be seen in all types of marine ecosystems, but their highly varied communities, unpredictable movements and behaviors, and the fact that they spend about 95% of their time under water have made them difficult to study. Each orca community worldwide maintains its own repertoire of behaviors, including diet and family patterns, as well as its own vocabulary of vocalizations.

Today, thanks to the dedication of whale researchers a picture is beginning to form of the highly refined adaptations and social sophistication of this remarkable species.

The Southern Resident Orca Community

Most of what we know about the Southern Resident orca community comes from a long-term demographic survey conducted by the Center for Whale Research on San Juan Island. The Center has been conducting photo-identification research on this orca population continually since 1976.

Dr. Michael Bigg, who pioneered field research on orcas in the early 1970’s, designated the 70 or so orcas he found in southern BC and Washington the “Southern Resident community” to distinguish them from the 120+ members (now over 250) of a different orca community found in northern BC and Alaskan waters. The three Southern Resident pods, known as J, K and L pods, usually travel, forage and socialize throughout the inland waters of the Salish Sea (Puget Sound, the San Juan Islands, and Georgia Strait) from late spring through late summer seeking chinook salmon, which provide about 80% of their diet.


By 1990 researchers had established that female orcas average over fifty years longevity and can live for eighty or more years in the wild, while males average around thirty years and may live to around fifty or sixty. A great deal of experience and knowledge may reside in orcas of advanced years, and is passed down through generations. Female orcas and humans along with few, if any, other mammals, live 3 or 4 decades after their reproductive years. This “post-menopausal” lifespan is believed to be crucial to maintaining cultural values and traditions. As with humans, the wisdom of the elders is essential for the stability and well-being of the entire community.

Social Structure and Behavior

The Southern Resident community is an extended family, or clan, that is distinct and separate from all other orca populations. Both male and female offspring remain near their mothers throughout their lives. No other mammal known to science maintains lifetime contact between mothers and offspring of both genders. Unlike all other mammals except humans, orca females may survive up to five decades beyond their reproductive years, which begin at around 14 years of age and continue until their late 30s or early 40s. Each individual can be identified by its unique fin shape, markings and color patterns and can be identified by sight or photograph. Using photo-identification methods, each has been identified by the Center for Whale Research with a specific alphanumeric designation, such as J2 or L12, and the movements and behavior of each member and group can be studied over many decades. After each newborn has survived its first winter they are also given more familiar-sounding names by The Whale Museum, such as “Luna” or “Samish.” When Southern resident pods join together after a separation of a few days or a few months, they often engage in “greeting” behavior. Ritualized formations of each pod face one another for several minutes, then gradually merge into active groups, each existing of members of different pods, accompanied by intense underwater vocalizations and spectacular “play” behavior.


From October through June, K and L pods tend to disappear to coastal waters over the continental shelf between northern California and SE Alaska, while J pod often reappears in the inland waters. All three pods visit lower Puget Sound during fall months in search of chum salmon. They are capable of swimming at speeds of 30 mph and usually swim from 75 to 100 miles every 24 hours. In 2016 the Southern Residents were comprised of just 84 members.

Endangered Status

Southern Resident orcas were listed as endangered under Canada’s Species at Risk Act in 2004 and under the United States Endangered Species Act in 2005. This came after an almost 20% decline in the population between 1995 and 2001. The historical practices of shooting and capturing the Southern Residents initially decimated the population. Current threats include potential disturbance from vessel noise, especially large ships; toxic industrial chemicals such as DDT, PCBs and flame retardants; and the decline of their primary prey Chinook salmon. Lack of food causes whales to draw from the energy contained in their insulating blubber to survive. When their blubber layers are partly consumed due to starvation, the bioaccumulated toxic chemicals such as polychlorinated biphenyls (PCBs) that have built up in the blubber are flushed into the whales’ bloodstreams. There they mimic and displace normal hormones, reducing the body’s immunity to infection and disease and disrupting reproductive and neurological systems. It is this double-whammy effect of malnourishment compounded by toxic contamination that likely led to many of the deaths of the Southern Resident orcas. In addition we now know through the Center for Conservation Biology that the female whales are experiencing a high rate of late-term miscarriage most likely due to lack of food and toxins.

The fate of our local orcas, and all other killer whales around the globe, is inextricably linked to the health of marine ecosystems. These intelligent and resourceful creatures will do well as long as the basic food supply on which they depend is available. Orcas are at the top of the food chain so all the other sea creatures from krill to sea lions must prosper if the orcas are to survive. Here in Washington State and British Columbia, our marine water quality and healthy salmon runs are crucial to the presence and survival of the Southern Residents as well as the transients.