Bigg’s killer whales, also known as Transients, are famous around the world because of their fantastic and dramatic hunting soirees. They are the mammal hunters. Many videos and documentaries about Bigg’s killer whales have revealed why these orcas are top predators in the sea. Able to take down Steller sea lions weighing in at over 1100kg, with canines similar to that of a Grizzly bear, Bigg’s killer whales are a feared predator among other marine mammals.
Along the coast of the Pacific Northwest, West Coast Bigg’s killer whales number around 400 individuals. They have a vast home range which extends from Alaska to Northern California, and with a tendency to be continuously on the move, it’s difficult to track every single whale in the population year-to-year. Transient killer whales were listed as Threatened under the Species at Risk Act (SARA) in 2003. In recent years, their population has been growing, with more and more sightings within the Salish Sea year round. A significant factor in the population rebounding is the return of Harbour Seal populations to stable, healthy levels for the first time since the Marine Mammal Protection Act was implemented in 1972.
Learn more about the population of Harbour Seals in British Columbia
Bigg’s killer whales do not interbreed with resident orcas. In fact, genetic studies show that this killer whale eco-type has been genetically distinct from all other eco-types of killer whales for a minimum of 750,000 years. The social structure of Bigg’s killer whales differs from the tight-knit pod structure found in resident populations. Bigg’s killer whales tend to travel as a matriline—a female and her offspring, however, members may split off from the group, especially mature daughters and any of their offspring. Because Transients hunt mammals, the optimal number of whales in one group appears to be about 3-7 individuals. This structure allows them to effectively hunt while keeping detection by their prey to a minimum.
Bigg’s killer whales eat a variety of marine mammals including Harbour seals, Harbour porpoises, Steller and California sea lions, Dall’s porpoises, Pacific White-Sided dolphins, and occasionally other whales such as Minkes, and juvenile Grey and Humpback whales. Because they are at the top of the food chain, they accumulate high levels of toxins in their bodies which can impair their immune systems, reproductive systems and the development of fetuses.
Learn More About Bigg’s Killer Whales!
Infanticide in a mammal-eating killer whale population
Cultural traditions and the evolution of reproductive isolation: ecological speciation in killer whales?
Clash of titans: Killer whales do battle with humpbacks off B.C. coast
High PCB Concentrations in Free-Ranging Pacific Killer Whales, Orcinus orca: Effects of Age, Sex, and Dietary Preference
The Marine Detective: What’s the Bigg’s Deal?!
DFO’s Photo Identification Catalogue of Bigg’s (Transient) Killer Whales From Coastal Waters of British Columbia, Northern Washington, and Southeast Alaska