Orcas (Killer Whales)
Killer whales are the ultimate (apex) predators of the world’s oceans, above even great white sharks. Here in the Pacific Northwest they serve as ambassadors to one of the richest marine ecosystems on our planet. However, the bio-diversity in the Pacific Northwest is astonishing and includes many other marine mammals: minke whales, gray whales, humpback whales, Dall’s porpoise, harbour porpoise, California sea lions, harbor seals, elephant seals, Stellar’s sea lions, and an unbelievable range of marine birds. Download our ‘free marine mammal guide’ & ‘free marine bird guide’.
Killer whales along the coast of British Columbia and Washington are among the most studied whales in the world. Intensive field research in this region has been undertaken for almost 35 years. These studies have provided increased knowledge about these whales, yet there still is much to be learned. Orcinus orca, better known as killer whales, are whales with teeth and are in fact the largest member of the dolphin family. They are found in all of the world’s oceans yet prefer colder water temperatures. Orca are mainly black with white markings located on their bellies, behind their dorsal fins (called saddle patches) and on the sides of their heads (eye patches). There are three genetically distinct groups of orca that roam all the world’s oceans: Resident, Transient and Offshore.
Resident Killer Whales
Resident orca travel in large family groups, or pods (sometimes exceeding 80 animals at one time). They are extremely vocal and their diet consists of approximately 32 different species of fish, primarily salmon. To locate their prey, they make noises that bounce back from nearby objects. This is called echolocation. With the help of sound, they can build a picture of their underwater surroundings. Resident killer whales on the BC coast are divided into two groups, the NORTHERN community and the SOUTHERN community. The population of orca that resides in the waters surrounding southern Vancouver Island is made up of three pods; J, K and L pods and are commonly referred to as the Southern Residents. They frequent the Pacific Northwest area in the summer months, feasting on salmon populations that are running from the Pacific Ocean to the Fraser River to spawn (April-October). The Southern Residents have been researched for the last 35 years and each orca has been photo-identified (picture ID, named, aged). The markings on their backs, which are behind the dorsal fin, are called saddle patches. These ‘saddle patches’ are essential like a human fingerprint, which allows for the approximately 87 orcas to be individually identified. The three Southern Resident pods mate amongst each other and do not interbreed with the Northern Residents.
Northern Resident Killer Whale sounds: ‘click’ on speaker
Southern Resident Killer Whales sounds: ‘click’ on graph
Transient Killer Whales
Transient orca are genetically distinct from residents and travel in small groups (approx 1-8 animals), vocalize infrequently and eat marine mammals, including seals, porpoise and other whales. Transients are opportunistic eaters. They do not vocalize as much as resident killer whales because many of their prey have effective underwater hearing. A more successful hunting strategy used by transients is to quietly stalk their prey using surprise to advantage with fast animals such as porpoise. Vigorous displays, such as breaches and playing, are seen less frequently in transients than residents, for fear of their prey being alerted to their impending approach. The occasions when transients do show a lot of surface activity are during the act of subduing or killing their prey. Depending on the size of the animal being killed, it can be tossed around like a tennis ball, thrown between individuals using powerful tail slaps, or forced underwater repeatedly until exhausted and drowned.
Transients can be seen all along the western coast of North America, from Glacier Bay in Alaska to the southern California coast. They tend to hug the coastline, examining each cove for unsuspecting prey that will make their next meal. They are sometimes seen far from shore, although the extent of their range in the open ocean is unknown. Transients can be seen year-round.
Offshore Killer Whales
Offshore orca travel in very large groups, use frequent vocalizations and a great deal of echolocation. It is thought that these killer whales feed on schooling fish, however nothing has been confirmed and the possibility that off-shore orca also hunt marine mammals cannot be ruled out. Many details about offshore orca are still unknown, as they were only discovered in the early 1990′s. They tend to spend most of their time far from the coastline in very open and exposed waters. These whales have a large proportion of nicks and scarring, relative to transient and resident killer whales, and one hypothesis is that sharks could be an item on their menu. One pod of California transient orca are known to hunt large sharks regularly with an apparent taste for the shark’s liver.
Most encounters with offshore orca have taken place near Haida Gwaii (formerly Queen Charlotte Islands) and 15 or more kilometers off the west coast of Vancouver Island. However, recently (2003 & 2004) we had a very large community of offshore orca travel into the protected waters of the Pacific Northwest (120+ animals). This was a very unexpected pleasure, as many of us had never seen such a strong presence of this distinct group of orca in our area before.
Orcas vocalize regularly while going about their various activities. The clicks that you hear are the sounds orca use to echolocate (search) for food and other underwater objects. The other sounds (more high pitched) are calls that the whales use to communicate with each other. The forehead (or melon of an orca) is used to generate the wide variety of sounds that the whale is capable of producing. Sounds are generated when the whale forces air in and out of the complex network of passages and cavities in the melon. You can learn more about and hear samples of echolocation and vocalizations provided on our own website (click to hear), and you may also download the file.
Resident, transient, and offshore orca have very different vocabularies. Both the sound of the calls and the number of calls vary substantially from population to population. Transient orcas vocalize significantly less than residents because they normally don’t use sound while foraging for food. Residents will send out calls to other residents and use sonar clicks to locate their prey. Transients, on the other hand, usually hunt silently, listening and looking for their prey. It is speculated that the reason for this is that the dolphins, porpoises, seals, and sea lions that constitute the transients’ primary prey could recognize transient calls and thereby rob the transients of the advantage of surprise. Transients normally begin to vocalize during or after an attack.