Killer Whales, Part II

We’re still getting feedback from passengers who were on board September 23, 2007 when we saw Killer Whales just beyond the Farallon Islands. When a couple of the whales came up from underneath our boat to glide momentarily alongside we were enthralled, no wonder we’re still talking about that trip. SFBay Whale Watching photographer Ed Estes and I were both taking pictures that day and usually from different sections of the boat. I couldn’t wait to see what he captured...as usual he got some stunners.



Chances are that the individual Killer Whales that we saw on September 23rd are known to researchers. We now know that they were “transient” Killer Whales. Known pods of transients range widely between California and Alaska . They were not the same Killer Whales that visited our area last winter, those were “resident” whales from the Washington state region. They can be identified by their dorsal fins and the gray “saddle” markings behind the dorsal fins. Using photo-identification researchers have cataloged over 200 individual transient Killer Whales.




I was surprised to learn that transients and resident Killer Whales are genetically distinct and are considered by some scientists to be separate species. They differ in diet; transients prey on marine mammals (sea lions, porpoises, dolphins, even other whales), whereas residents are fish eaters (salmon, tuna, herring).


It was interesting that Doreen Gurrola, our Naturalist, noted the length of the whales’ dives each time because that was a way to establish that these were transients, not residents. It seems that transients dive for longer periods than residents (Doreen noted that each dive lasted about 10 minutes - bingo: transients.), a technique suited for stealth hunting of marine mammals.



Not only do longer dives facilitate stealth hunting but quieter whales evidently do too, because transients vocalize less than residents, using fewer calls and sonar clicks to locate prey. Transients seem to depend more on sight and hearing to locate prey than seaborne conference calls. Although increased vocalization has been reported after a transient prey attack.




I’ll be posting some passenger photos of the Killer Whales from this trip next time, and then I’ll show you some of the other terrific things we’ve been seeing lately besides Killer Whales (yes, the Humpbacks are still out there!).

Photos by Ed Estes. Text by Kathleen Jacques.