Who are the Transients?

Transient killer whales, also known as Bigg’s killer whales are a genetically and culturally distinct population or ecotype of orcas within the Pacific Northwest and prey exclusively on marine mammals. The name “transient” came from killer whale Researcher Dr. Michael Bigg who observed their behavior as transient or more nomadic. Later, transients also became to be known as Bigg’s, which was in honor of the belated killer whale researcher who first began the identification and cataloging of orcas, determining the different ecotypes.

When Dr. Bigg began his studies transients were far more elusive than Residents and seemed to have less predictive travel behaviors. Since that time, there has been a steadily growing presence of transients within the Salish Sea due to a flourishing food source, which has allowed us to observe that the prenotion of the “transient” behavior is actually not the case. Instead, multiple matrilines appear to have seasonal and location preferences. For example, the T65As spend much of the summer in Puget Sound proper, while the T18s show up in the northern Salish Sea during late summer and early fall.

Like other ecotypes of orcas, Bigg’s orcas are matriarchal, which means females are the leaders. Similar to their Resident cousins, there are separate family sub-groups or matrilines that are centered around the mothers or grandmothers. However, unlike Residents, transients spend most of their time traveling in smaller groups of immediate family, averaging about 3 to 7 individuals to optimize hunting and prey sharing.

Transients often get the reputation for being “outcasts” or solo creatures. And while there are some instances of orphaned or single orcas observed alone, the majority of the transient population is incredibly social. Extended families and other matrilines will often meet up and travel together for short to long periods of time to socialize or breed. It has been observed that when multiple pods of transients are together, young calves will play, while mothers will spend time with one another. There have even been cases where individuals from one matriline will break away from their mother and spend time with aunts and cousins, to return to their mother later on.

With the increasing amount of prey within the Salish Sea, we are beginning to see record numbers of Bigg’s killer whales in our waters, which allows us the opportunity to learn even more about this once mysterious and illusive ecotype.

Diet

Transient orcas feed exclusively on marine mammals such as seals, sea lions, porpoises, dolphins, and whales. Their diet defines their culture, lifestyle, and travel patterns.

Transients are far less vocal than their Resident cousins, which allows them to be stealthy and ambush their prey. Instead of regularly using echolocation, which could risk tipping off an alert seal of their presence, transients will use passive listening to remain undetected, occasionally using echolocation to create a quick snapshot of where prey may be located.

Since transients prey share similarly to Residents, it is necessary for them to travel in smaller groups. Having a smaller group makes it more efficient to both hunt but also share prey. An average adult killer whale requires up to an estimated 350 lbs of food. A pod of 4 Bigg’s orcas may need upwards of 1,400 lbs of food in a single day, which could amount to about 7 adult harbor seals weighing 190 lbs. The larger the matriline, the more food it will require, which makes smaller groups far more efficient. (Please note numbers are not exact and are rough calculations to depict the dietary need of transients.)

Matrilines & Identification

Each matriline is identified by the eldest female within the group and given an alphanumeric ID beginning with the letter T (to denote the transient population). Each member within the matriline will be assigned an alternating alphanumeric ID based on birth order, letters and numbers will alternate as new generations are born.

In most cases, males will spend the entirety of their lives with their mother (and maternal grandmother if she is still alive). However, female orcas will break away and form a new matriline once they begin to have calves of their own to keep pod sizes small. Once a female and her calves begin to travel separate from the rest of their family, they become identified as a new matriline.

For example, T65 had two female calves who received the alphanumeric IDs of T65A and T65B. Once T65A began to have her own calves, she broke off into a new matriline now called the T65As. Her calves all have IDs beginning with T65A followed by a number assigned in birth order. T65A’s eldest offspring is T65A2, followed by offspring T65A3, and so on. When T65B began to have her own calves and travel with them separately from her extended family, her matriline was identified as the T65Bs.

While the alternating alphanumeric is the identification technique for the majority of the Bigg’s population, there are some variations in numbering. This is the case when a relation wasn’t known when the orca or matriline was first discovered. An example of numerical variation is the T18s, which also include the T19s.

As the transients have become more prevalent in the waters of the Salish Sea, many will come to recognize them by nicknames. The nicknames are usually assigned to an individual by the person who first identified or cataloged them. Generally, the nicknames come from the locations they were discovered, but there are many others who received names from folklore, First Nations languages, in honor of people, characteristics, and more.

Download the free Bigg’s Photo-Identification Catalog by Canada Department of Fisheries and Oceans.

Please note, there are over 300 individual Bigg’s killer whales cataloged. While our goal is to eventually feature all the unique individuals on this page, that will require ongoing work. Our current catalog will be based on the matrilines who spend the most time within the Salish Sea as well as the matrilines we have encountered. We will continue to build our catalog as we go, so keep checking back for updated information.

©All photos and content belong to Orca Conservancy unless otherwise stated.