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The Killer Whale (Orcinus Orcais) the largest member of the dolphin family and they tend to be found in groups called pods, a group of related families. Occasionally two or more pods join together temporarily and can consist of up to 100 whales.

There are three different populations of Orcas encountered along the West coast of North America. These three groups appear to be genetically different and do not interact socially–in fact, observed behaviors indicate that they normally avoid contact with each other.

Offshore, Resident and Transient, I have been lucky enough to photograph Resident and Transient Orca Killer Whales.

The resident population is comprised of groups of genetically related clans or extended family groups of Orcas. These clans have established territories and fairly predictable patterns of movement within those territories. They travel in pods and sub-pods, often groups of up to 20 whales or more with individuals scattered over a wide area.

Transients, on the other hand, have neither established territories nor predictable patterns of movement. They swim in small groups of two to five or six, usually in close physical proximity.

Researchers have recently had several encounters with the third known West Coast Orca population, currently labeled the “offshore”. These whales have been encountered primarily in the open ocean, and in large groups of 30 to 60.

One of the primary reasons residents, transients, and off shores exhibit different behaviors is that their diets are very different. Residents feed almost exclusively on fish, and exhibit a strong preference for salmon. At the moment it is believed that the off shores are exclusively fish eaters as well, but, given the relatively small number of encounters with the off shores, it can’t be said with certainty.

Transient whales feed primarily on marine mammals. Transients observed in waters of B.C. and Washington State have been seen preying on seals, sea lions, dolphins, porpoises, and other species of whales. Their diet, however, isn’t strictly limited to marine mammals. Transient killer whales have also been observed eating sea birds, and the stomach of a dead transient whale recovered up in Alaska contained the remains of a moose. Apparently the moose chose the wrong moment to swim from one Alaskan island to another–something that moose, deer and other land animals frequently do.

From the website whalesbc

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