Silent Killers vs Chatterboxes: Differences in Transient and Resident Killer Whale Communication
There are two subspecies of killer whales that inhabit the eastern North Pacific: transient killer whales and resident killer whales. These two subspecies have not interbred for at least 250,000 years and display drastic differences in social structure, behavior, prey preference, morphology, and, interestingly, communication styles.
Transient killer whales feed exclusively on other marine mammals, such as seals, porpoises, sea lions, and even the occasional large whale. These marine mammals have excellent underwater hearing and are able to detect transient killer whale calls from several kilometers away and display anti-predator behavior when exposed to these calls. Therefore, “eavesdropping” by potential prey is an issue for transient killer whales, and it has shaped their vocal behavior. Transient killer whales are almost entirely silent as they go about their day. They only become vocal in two instances: after they have made a kill, and when they are participating in surface-active, social behaviors.
Resident killer whales, on the other hand, only feed on fish. Salmonids, their preferred prey species, have very poor hearing at the frequencies in which killer whales communicate. Therefore, resident killer whales are often loud, chatty, and can be generous in their use of echolocation calls.
There are three types of vocalizations used by killer whales: clicks, whistles, and pulsed calls. Clicks are used during echolocation and help whales orient themselves and locate prey. Whistles are used for socialization and in short-range communication. Pulsed calls are the most common form of killer whale vocalizations; they are used in group recognition and coordination of behavior. These calls are used by biologists to distinguish individual groups of whales.
During studies of resident and transient communication, researchers find that residents produce pulsed calls at a higher rate than transients. One study, published in 2005, showed that transients produce no vocalizations whatsoever apart from when they have made a kill or are participating in surface-active behaviors. What is the reasoning behind food-associated vocalizations? While we still are not sure, it is likely related to socialization. Transients frequently share prey amongst each other and high rates of vocalization after a kill may aid in doing so.
Photo: Eva Saulitis (left) and NOAA Fisheries (right)
Deeke V., Ford JKB., and Slater P. 2005. The vocal behaviour of mammal-eating killer whales:
communicating with costly calls. Animal Behavior, 69: 395-405.
I was so thrilled to spot a few members of this resident pod flitting around the bay this afternoon (6/18/18). They were spread out, likely searching for salmon along the shoreline. AP pod was seen extensively last summer, but hadn’t been seen for many years prior. They are truly a mysterious pod!
Here is adult male AP9 making a few close passes by our vessel, the M/V Discovery.
Fluctuating asymmetry, the asymmetric presentation of a trait that is normally symmetric, can indicate genetic and environmental stress in animals. In killer whales, the saddle patch is normally a symmetrical feature, with the left and right saddle patches looking the same.
J14 (top) with normal, symmetrical saddle patches and L88 with asymmetrical patches. Photos by Ken Balcomb (Center for Whale Reserach)
However, the southern resident killer whale (SRKW) population shows an abnormally high levels of fluctuating asymmetry in their saddle patches in comparison to other populations, such as transients and offshores. The paper “Fluctuating asymmetry in the saddle patch shape of the Pacific Ocean killer whale (Orcinus orca) populations” by Mäkeläinen et al. 2013 measured saddle patch symmetry in 6 killer whale populations in the North Pacific. The SRKW showed the highest levels of fluctuating asymmetry.
The southern residents were listed as endangered in 2005 and their population has been on the decline in recent years. Why would the SRKW have asymmetrical saddle patches? One possible explanation is low genetic diversity. The SRKW do not interbreed with other killer whale populations; this, combined with population decline and inbreeding, has led to low genetic diversity, which could allow for asymmetrical saddle patches to appear more frequently in the population.
Book Review of “Orca: How We Came to Know and Love the Ocean’s Greatest Predator”
Jason M. Colby’s newly released book documents the historical killer whale captures in the Pacific Northwest of the 60s and 70s, as well as subsequent captures in the 80s in Iceland.
The topic itself is not new; there are several other books that highlight this subject, such as “Puget Sound Whales for Sale” and “Of Orcas and Men,” but Colby’s book adds new (and sometimes gruesome) details about the captures and includes new interviews with the men who orchestrated them. One particularly hard to read account comes from Jeff Foster, who aided with some of the first killer whale captures in Iceland:
“Roger de la Grandiére, a French collector for Marineland Of Antibes near Nice, netted a female orca off the coast of Iceland. Without the experience and equipment to handle her, however, his crew lifted the animal by the tail and broke her back.”
Additionally, Colby does not focus on present day conflicts of killer whale captivity and instead aims solely to present the historical records of captures and the impacts they had. What sets his book apart from the others is perhaps its message and in-depth interviews with the man who started killer whale captivity–Ted Griffin. Griffin was the man who acquired Namu, the third killer whale in captivity and arguably the one who set off the world’s love for killer whales.
After Namu died, Griffin and his partner, Don Goldsberry, went on to capture dozens of killer whales for parks around the world, such as SeaWorld and several now defunct marine parks. They killed many in the capture process (including calves) and in some instances, they attempted to hide the bodies by slitting their bellies and weighing them down so they would sink. For these reasons, Griffin is often vilified and hated by those who care about killer whales.
However, through rare interviews with Griffin, Colby tries to highlight a new side of him: a caring man who loved killer whales and just wanted to share them with the world. Colby argues that without these captures, however terrible and cruel they were, the world would never have come to adore killer whales and give them the iconic status they enjoy today.
For those of us who do not agree with captivity, this is a hard to fact to face. It is true that without captivity, we may still be shooting and killing killer whales for fun and out of fear. Captivity changed our perspective on these creatures and showed the world they are not dangerous man-eaters as once thought. Personally, I am against killer whale captivity, but acknowledge these early captures were vital in changing the perspective on killer whales. However, I still do not view Griffin favorably; though the author tries to show us he is not the evil heartless man as he is so often portrayed to be, it is difficult for me to reconcile his apparent love for killer whales with the suffering and cruelty he knowingly and willingly inflicted upon them.
This is a good book for anybody interested in killer whales, and especially those who are involved in the debate over killer whale captivity.
Killer whales are largely considered “xenophobic, that is, reluctant to interact with individuals outside of their own population. However, genetic studies have revealed low levels of gene flow between killer whale populations and even ecotypes!
In the above study, the authors analyzed genetic data from the following populations: Russian residents, Bering Sea residents, Southeast Alaska residents, offshores, Alaska transients, California transients, and Icelandic killer whales. They used various programs to determine the paternity and maternity of individuals, matings between populations, and matings between ecotypes. Some of their results were fascinating. They found:
High rates of gene flow between Alaska transients and California transients (CA20 was identified as an F2 migrant, the result of an Alaska transient breeding with a California transient).
High rates of gene flow between Russian residents and Bering Sea residents.
Russian residents that migrated to the Southeast Alaska resident population.
An individual that likely had an offshore mother and transient father.
Two Icelandic killer whales that had Pacific transient fathers (one of which was identified to likely be an Alaska transient).
While very rare, these results tell us there are some levels of inter-population and even inter-ecotype matings in killer whales. The transient/offshore matings likely happen in offshore habitats when the two ecotypes happen upon each other. The Icelandic/transient matings are harder to explain given the sheer geographic distance, but the authors propose a few ideas: “…the supposed mating between females from the IC population (the North Atlantic) and transient males (the North Pacific), suggested by detection of F2 immigrants between these populations, must have involved either the long-distance movement of mating individuals or entire pods, or gene flow through intermediary populations. Killer whale social groups are capable of migration over distances of several thousand kilometers in a season (Sternson & Simila, 2004; Dahlheim et al., 2008), so the possibility of long-distance associations cannot be excluded.”
Some of the identified migrants between populations are possibly not true migrants, but may have been the result of temporary associations between populations. For example, there were two proposed F1 migrants from the Russian resident population to the Southeast Alaska resident population. However, given that these whales were not identified as belonging to any identified Alaska resident pod, it’s likely they were temporarily associating with the Alaska residents rather than being permanent migrants.
Regardless, it’s still fascinating to know some cases of breeding outside populations and ecotypes occur. We still have much to learn!
Alaska is vast; the state holds more coastline than the contiguous United States combined. With its short summers, fierce winters, and weather than can change in the blink of an eye, oceanic field research is difficult and often severely limited.
Studies on Alaska’s killer whales began in in the early 80s in the Kenai Fjords and Prince William Sound region in southcentral Alaska. Biologists, such as Craig Matkin and Eva Saulitis, began documenting individual resident and transient pods that traversed the region. After many years of effort, they eventually developed a identification catalog of killer whales ranging from Kodiak Island to Southeast Alaska. In total, they identified over 700 individual resident killer whales and over 100 Gulf of Alaska transient killer whales in these regions. These whales are fairly well-studied and we know much about their distribution, feeding habits, travel patterns, and behavior.
However, there is another group of killer whales Alaska that is more than double the size of the southern Alaska resident killer whale population. Biologists have estimated that there are over 1,500 resident killer whales alone that live in Western Alaska in the waters of the Bering Sea and off the Aleutian Islands. There are also unique groups of transients who appear to be separated from the Gulf of Alaska transients. Who are these whales? What do they eat? Where do they travel?
Click below to read more about Alaska’s mysterious killer whales.
We do know some things: resident killer whales in Western Alaska likely depend more on non-salmon prey, such as Atka mackerel. These whales are also known thieves; resident killer whales in the Bering Sea are known to depredate local commercial fishing operations. They are adept and skilled at removing halibut, turbot, and blackcod from longliners (to read more about killer whale depredation in Alaska, check out my article in Orcazine.)
The transients in Western Alaska are big, burly, and frequently take down large baleen whales as prey. In Unimak Pass in the Aleutian Islands, there is a seasonal gathering of transient killer whales that assembles in order to intercept migrating gray whales.
A subadult male killer whale attacking a gray whale in Western Alaska. Photo by John Durban.
These transients don’t appear to linger around after the gray whale migration. Tagging studies show they disperse into the Bering Sea. Some transients in Western Alaska also appear to focus their energy on fur seal colonies around the Pribilof Islands; these fur seal “specialists” are genetically related to transients found off the coast of Russia.
Perhaps the most fascinating aspect of Western Alaska’s transients is their potential range. One tagged transient in the Bering Sea traveled rapidly over 1220 miles towards the central sub-tropical Pacific, roughly halfway to Hawaii. These forays into warmer waters are also evident on their skin. Some transients in Alaska bear the oval scars from cookie-cutter sharks, which are only found in the tropics and subtropics. What are they doing? Where are they going? Are these long-distance trips regular for these animals? What are they eating when they aren’t in Alaska? The answers to these questions is still unknown.
A male transient in the Central Aleutian Islands bearing cookie cutter shark bite scars. Photo by Dave Ellifrit, NOAA Alaska Fisheries Science Center, NMFS
Permit No. 782-1719.
While Western Alaska holds some of the most tantalizing killer whale mysteries, some pods of southern Alaska residents are as equally mystifying. Many resident pods are documented every year and are easy to track and study. Others, however, are evasive and where they go and what they do is unknown. AP pod is a great example of this. This pod of about ~19 individuals was photographed in 2003 and 2012 by biologists. They are so poorly known that for a long time they were placed in a category of whales known as the “gray box” residents, an assemblage of individual whales that were only seen once or twice and pod relations could not be worked out. In 2012 they were placed into their own pod category, but family relationships are still unknown.
I was fortunate enough to photograph and spend time with AP pod for several weeks in 2017. They appeared one day in Kachemak Bay, Alaska out of the blue and for whatever reason, stuck around for over a month. I documented new calves and I believe I have worked out some family relationships. It may be many more years before AP pod is seen again; we don’t know their range or where they spend most of their time.
AP pod male AP18 and a female, probably AP7.
Some resident pods in Alaska are so poorly known that not even established biologists have records of them. Last summer, I photographed a large pod of residents in Kachemak Bay. These whales were distinct and easy to identify. Surely, they would be in the catalogs. Despite weeks of painstakingly analyzing and comparing photographs, I could not find no matches to identified killer whales. I emailed the photos to Alaska’s killer whale biologists and they too could not identify the whales. It is likely they are a newly documented resident pod.
An adult male from the newly documented resident pod. Note the yellow patches on the saddle patch; these are diatoms, a type of algae that grows in cold waters, indicating this whale may have been in colder, more Arctic waters recently.
However, which population are they from? Western Alaska, or the southern Alaska resident population? Kachemak Bay sits neatly in the middle of southcentral Alaska, nestled between the vast western Alaska regions and the more populated areas of Prince William Sound and Southeast Alaska. While there has been no documented movement from Western Alaska killer whales into the region where southern Alaska residents inhabit, I have always had a hunch that Kachemak Bay may be a mixing zone of sorts. Given that these whales were traveling with AX27 pod, a fairly well-known southern Alaska resident pod, they are likely from said population, but I will always wonder.
There are still so many things to learn about Alaska’s killer whales. With a little luck and more time, we will hopefully unravel some of these mysteries.
Resident Killer Whales: The Ocean’s Most Dedicated Mother
On Mother’s Day, many of us take the time to honor our mothers and all of the time, energy, effort, and love that has gone into raising their children.
For resident killer whales, an unnamed subspecies of killer whale found only in the North Pacific, motherly love transcends all other boundaries found in the animal kingdom. In resident killer whale society, a female’s offspring never leave her side.
This phenomenon, known as natal philopatry, is seen in many species, but killer whales take it to a whole new level. Both female AND male offspring stay with their mother for their entire lives. Natal philopatry of both sexes is very rare in mammals, being seen only in two bat species, pilot whales, and of course, resident killer whales. 
Male resident killer whales in particular are true “mama’s boys.’ While mature female killer whales will retain some degree of independence from their mothers, males are extremely dependent on their mothers. In fact, a male resident killer whale is 3.1 times more likely to die in the year following the death of his mother. For males over the age of 30, the risk of death increases over 8 times after the death of their mothers. This may be because older mothers often provision their adult male offspring. Without mom around to help feed him, a male may have more difficulty surviving. For males, having mom around also means they have higher reproductive success.  
Alaskan resident male AP10 and his probable mother, AP2.
Killer whale moms are so important that they are one of only a few species to display reproductive senescence, also known as menopause. In most animal species, a female continues to reproduce for her entire life. In killer whales, females generally stop reproducing around 40 years of age, but can easily live 30-40 years more after reproduction ceases. One main hypothesis that explains this curious aspect of killer whale biology is that elderly female killer whales are repositories of information that aid in group survival. These “grandma” killer whales are the leaders of pod movement during foraging, and their leadership is especially important in years when salmon––resident killer whales’ main prey source––is low. 
Moms are important to us all, but for killer whales, a mother is the ultimate key to survival. Without such dedicated mothers, killer whale society as we know it would likely be radically different.
Happy Mother’s Day to all mothers out there, especially the ones of the flippered variety.
For further reading, please refer to the sources under the cut.
The orca-centric magazine Orcazine has published my article on killer whale depredation in Alaska, and it includes a few of my own photos as well! I’m excited that a piece of my writing has been officially published.