Simple Orca sociology

When I started reading about Orcinus orca I was pleasantly surprised. They are all over. Very much a symbol of the islands. The house down the street is “Orca Villa”. Bumper stickers. Sports teams. But as I started reading I was quickly fascinated by a couple of things. How recent a lot of the knowledge of orcas is. How little we know about what they do underwater and at night. And what we know about their sociology.

Out at Point Roberts I had seen for the first time the identification charts and realized that there are few enough individuals that we can learn to recognize them. What I hadn’t realized was that there are three distinct societies of whales. Distinct enough that some feel that they should be separated into races. The ones that we see most often in the San Juans are the Southern Residents. But there are transients and offshore groups as well. And there are the Northern Residents.
Resident

  • Salmon eaters
  • Larger pods (6 to 50)
  • Smaller home area
  • Dive for 3 or 4 minutes
  • Larger range of vocalization
  • Lots of echolocation
  • Rounded dorsal tip – sharper rear angle with open saddles

Transient

  • Marine mammal eaters
  • Small pods (less than 6)
  • Dive for 5 to 7 minutes
  • Minimal vocalization
  • Pointed dorsal fin with grey saddles

Offshore

  • Salmon maybe?
  • Larger pods (25 or more)
  • Outside Puget Sound
  • Continuously rounded dorsal tip – no sharp rear angle though
  • Saddle patch gery or open

 



This entry was posted on Thursday, November 2nd, 2006 at 7:29 am and is filed under Marine Mammals, Orcas. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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