Pods from one community have never been observed traveling with those from another community, although their ranges partly overlap. The call dialects of the four communities are also distinct. The Northern Resident Community, which is found primarily in the Johnstone Strait area and northern British Columbia, is made up of about 216 whales in 16 pods. Another community of orcas, called Transients, can be found in small groups from Mexico to the Bering Sea. They appear only occasionally in the Salish Sea, usually near Vancouver Island.
Transients specialize in a diet of marine mammals, especially seals, sea lions, and porpoises.
There are about 170 transients, but they travel in small groups of one to five individuals, staying close to shorelines, often near seal rookeries when pups are weaned. In 1991 another community, called Offshores, was discovered.