Did you know that some groups of transient (Biggs) killer whales show culturally distinctive foraging styles and prefer to forage with groups with similar tactics? And that, in fact, transients are not so transient? The Transient Killer Whale Research Project is working on increasing our knowledge about them. Check out their page for interesting new insights as well as impressive photographs! Read their latest update below: Interesting stories on transient orca abundance in the Salish Sea - by The Transient Killer Whale Research Project Here is a little information we have been working on recently. Transient Killer Whale Occurrence and Behaviour: I would like to explain a little bit about our current understanding of the occurrence and abundance of transient killer whales in waters off Southern Vancouver Island. There has been a lot of talk about the increase in transient killer whale sightings in recent years. We (The Transient Killer Whale Research Project) have been following the ecology and behaviour of mammal hunting killer whales off Vancouver Island since 2007. 1. Transients are not so transient. We have noticed certain pods prefer certain areas. Pods that frequent the waters off Southern Vancouver Island are seldom seen elsewhere throughout the season. Take for example the T002Cs, which we have encountered on numerous occasions off of Discovery Passage...rarely if ever are they sighted off Southern Vancouver Island. Other groups prefer areas off Tofino BC (T069s, T012A, T011s, T041s). 2. Association based on foraging: Certain groups show culturally distinctive foraging styles and prefer to forage with groups with similar tactics. This also shows in their occurrence. We have noticed certain groups like the T065As, T030s, T011s, T049As, and T049Bs, show up around the months of June-September. This time period coincides with the Pacific harbour seal pupping season. Other pods like the T060s, T002Cs foraging primarily offshore and target porpoise. 3. Increased Occurrence: Yes there has been an increase in overall sightings of transient orca. There is some bias to these accusations. The Southern resident population in recent years has spent more time away from coastal waters making whale watching much more difficult. Whale watchers must than search for other animals to entertain their guests, making transients a key target. The truth is there has been an increase in occurrence. A few reasons come to mind. In previous decades the harbour sea population was still rebounding from severe culls that drastically reduced the population to 10,000. The increase in harbour seals would increase the overall area use by their main predator transients. Another reason physical resource partitioning. The residents have been scarce, which opens a door for transients. This was shown in the months of March and April, where resident orca sightings were considered very high, and transient sightings low. This has changed with a huge increase in transient orca sightings. 4. Exotic transients: In recent years we have had the ability to ID transients from other populations. People are getting better at ID whales and making assumptions that the social organization of transients is similar to resident is changing. A huge issue is that when a person encounters a group of transients and IDs one animal they assume all other individuals are part of that family group. We have been following the occurrence of California transients in BC waters and are collaborating with the California Killer Whale Project on this matter. We have noticed they do associate with west coast transients, often in large congregations of more than 20 whales. Often they are sighted in open water not close to land (middle Juan de Fuca Strait), most common in the fall months. There have not been 100 different exotic transients in the area. Stats: Transient populations: Inner coast transients=280 Outer coast transients=220 (DFO Stat) California transients estimated=100 *160 AT1 Prince William Sound=7 Gulf of Alaska=100 Occurrence of transient killer whales in BC waters: 2013 sightings 231 reports 2014 sightings 220 so far Most common transient pods off Southern Vancouver Island: T065As, T060s, T030s, T049As T049Bs, T137s, T018s. Total transient pods in our records: 52 groups. California transients: About 20 identified individuals from our records. We are still working through more years of data and will have another update soon. Data by Josh McInnes and Kelsey Cullen. University of Victoria
Posted on: Sun, 16 Nov 2014 02:49:33 +0000
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