Bigg’s killer whales were formerly known as ‘transients’. In 2012, a push was made to rename this type of killer whale in memory of Dr. Bigg. Bigg’s killer whales range all along the west coast of North America, from California to Alaska. They are mammal-eaters, specializing on smaller marine mammals such as seals, sea lions, porpoises, dolphins, and occasional calves or juveniles of larger species such as grey whales and humpback whales. In fact, the term “killer whale” is derived from this type of killer whale, which is the only species of whale that kills other whales.
Bigg’s killer whale societies are based on a matriline structure, similar to resident killer whales, but offspring may disperse from their mothers once they reach maturity, especially females once they’ve had calves of their own.
For Bigg’s, traveling in smaller groups is important to be able to efficiently hunt and catch their prey. Unlike fish, marine mammals can hear very well underwater, so Bigg’s killer whales vocalize and echolocate very rarely while searching for their prey. Instead, they follow the coastline, checking each cove for unsuspecting prey and use passive listening to locate seals and small cetaceans. Bigg’s typically vocalize either during or directly following a kill; a time when they may also become very active with tail lobs and breaches. Bigg’s Orcas will create transient ‘superpods’ when several families come together to hunt, breed or just hang out.
Observers can often identify that a kill has occurred by the presence of sea birds. Seagulls will descend nearly immediately after a kill. Orcas will pass the kill between them as they swim and consume the carcass. Often an oily slick will appear at the surface where the kill took place.
A great resource for transient info, resource and encounters from the Salish Sea area on FB: https://www.facebook.com/pages/Transient-killer-whale-Research-blog-by-Josh-McInnes-c/259019844119284?fref=ts