Humpback Whales | Orca | Fin Whales | Whales & Sound | Identification of Whales
Orca
The common names for orca include 'killer whale' or 'blackfish' and, more recently, 'wolves of the sea'. Males typically range from 6 to 8 metres in length and weigh in excess of 6 tonnes. Females are smaller, generally ranging from 5 to 7 metres in length and weighing about 3 to 4 tonnes. The male dorsal fin can reach a height of 6 feet and the female dorsal fin half that, at 3 feet. They can swim at speeds up to and above 30 knots (56km/hr)!
Three distinct lineages of killer whales share the coastal waters of northern B.C.: Northern residents, Bigg's and offshores. Bigg's and resident orca are sighted most frequently in our research area. In the last 15 years we have only sighted offshore orca four times, three of which occurred in 2015. These lineages do not mix with each other and specialize in very different prey resources. Though they appear similar at first glance, the lifestyle and social behaviour of these populations are quite distinct from one another. Residents and Bigg's orcas will not socialize with one another even during the rare occasion they come face to face in the same area.
Read the following pages to learn more about each population of orca. You will discover that much of their behaviour, while unique, is also familiar. As with human populations, these orca lineages are distinguished more by culture than by their physical differences.
NORTHERN RESIDENTS
The term ‘resident’ was initially inspired by their reasonably predictable and consistent travel patterns as observed by researchers in the 1970’s. Their range extends from the southern portion of coastal Alaska to the northern half of Vancouver Island, and as exclusive fish eaters, resident populations tend to follow the yearly migration of salmon. Northern residents typically amass in the Johnstone Strait region in the middle of June – just as chinook salmon begin their journey towards the intricate network of rivers and streams along the coast. The whales continue to follow the Pacific salmon migrations, stretching upwards as far as Alaska until the last salmon disappear in late fall.
Using echolocation, resident orcas send out a series of sharp clicks to locate their agile prey. Sometimes, residents work as a collective, ushering a group of salmon into a tight ball to maximize efficiency. Other times, a catch is shared between close family members, especially between a mother and her calf. During hunting, feeding, travelling, and social interactions, resident orcas are highly vocal – layering high-pitched calls into rapid exchanges. Their communication is especially vibrant when different pods come together as a larger collective. Their calls sound excited and joyful – becoming a wandering, echoing dialogue involving dozens of distinct voices.
SOCIAL STRUCTURE
The Northern resident community of orcas is well known for their strong family bonds and acoustic dialects that separate one pod from another. This highly social community consists of over 200 whales and continues to grow with each season. Resident orcas have rich and established social structures that remain stable throughout generations. At its base, resident orca family structure is maintained by the matriline. Similar to family patterns found in African elephants, orcas (in this case, both male and female) generally remain with their mothers and closely related family members for their entire lives. The bond between mother and son are especially strong, tending to separate only by death. However, when daughters of the matriarch establish their own line of descendants, they may spend more time with their own families, or even break off to form sub-pods as their family expands.
Orcas bonded by closely related matrilines are referred to as pods. Most pods are composed of 1-3 matrilines, and tend to travel as a cohesive group. Not only are they joined by blood, but pod members share a common dialect – distinct from other, more distantly related pods. These unique dialects help researchers easily distinguish between various pods of residents. Dialects are most likely fostered by stable, close-knit relationships among pod members, and passed down through the matriline – learned by calves from their mothers and family.
Different pods of Northern Resident orcas are associated in larger groups called clans. There are 3 distinct clans within this community. A clan is a collection of pods that share a number of common calls, most likely resulting from a continuous lineage that long ago shared a common ancestral pod. As the ancestral pod grew in size, it probably broke into smaller sub-pods that developed increasingly distinct dialects as generations progressed. The acoustic tradition of each separate pod was passed on for generations, gradually incorporating slight acoustic variations, and resulting in the variety of dialects that we see today. Using this logic, the closer related members of a clan are, the greater amount of calls they will share.
TRANSIENT (BIGG'S)
Formerly known as 'transients', Bigg's orca are often referred to as the wolves of the seas. They are the whale that lead to the term “killer whale” since they hunt marine mammals, including other whales. What sets Bigg's orca apart from the well-known fish eating resident orca is that Bigg's prey on marine mammals. Most commonly, they pretty on harbour seals, but they are known to also hunt harbour porpoise, Dall’s porpoise, Pacific white sided dolphins, gray whales, minke whales and Stellar sea lions. Seabirds are also attacked, but not usually eaten. Many times juvenile orca are seen “playing” with seabirds, which might be an important means of developing hunting techniques. Bigg's orca have also been observed preying upon deer/moose that sometimes swim between islands.
They are more difficult to study because they live in smaller groups, usually consisting of 2-6 individuals. The family structure of Bigg's orca is much more fluid, with families breaking apart and joining other families for periods of time. However, like residents the relationship between a mother and her oldest son lasts a lifetime.
The range of Bigg's orca on the west coast of North America stretches from southern California to the Aleutian Islands of Alaska. Bigg's orca cover a large area in search of prey, continuously on the move to maintain their stealth tactic of hunting. If they stayed in the same area for a prolonged amount of time, prey would be alerted to their presence, thus reducing successful hunting. With this on-the-move lifestyle, they can easily travel over 100km a day.
All Bigg's orca share a common set of vocal signals, with some small varieties existing, but because of the Bigg's fluid social order, they have not developed the unique calls/dialects, like resident orcas. Additionally, because this population travels mostly in silence to prevent other species from detecting them, the opportunity for a specific dialect to be passed on to family members is minimized.When we detect Bigg's orca call types over the hydrophone we know which population we are recording but cannot determine the family group by distinct acoustic call types. They tend to use passive sonar, listening for the sounds of their prey, such as a splash from a swimming seal or a whistle from a dolphin. This is part of their stealth hunting style/tactic. If they were vocal while hunting, it could alert their prey to their presence. However, after a successful hunt, Bigg's can be quite vocal when socializing.
There is much more to be learned about Bigg's orcas, but they are more difficult to study than resident orcas. They tend to be hard to find and easy to lose, but as more research is undertaken throughout their known range, our knowledge and understanding of these enigmatic creatures will continue to grow.
OFFSHORE Orca
Relatively little is known about this population as they spend most of their time off-shore near the continental shelf. They feed on sharks and large bottom fish such as halibut. In 2015 we sighted offshores for the second time in our 15 years of research. During each event we were able to collect identification pictures as well acoustic recordings of their particular dialect, which is very different than that of Bigg's or residents.