I have a few random observations and tidbits of news to share since I last wrote about the Southern Resident killer whales, who recently arrived in the San Juan Islands — a little behind schedule but showing off a newborn calf. See the July 7 story in the Kitsap Sun and related entry in Water Ways.
The Southern Residents have settled down somewhat in their summer waters in and around the San Juans. One can follow their travels by joining Orca Network’s Sightings List or by checking the website for reports by observers.
I was interested in a comment made a week ago by Ken Balcomb of the Center for Whale Research following his observations of the new calf and his mother, along with the mom’s brother, who were all joined later by the calf’s grandmother. Here’s Ken’s comment:
“It would be fascinating to eavesdrop on the whale communications at this time, especially those of matriarchs J2 and K13. There is a mixing of incomplete subgroups and matrilines this year, and much less of a pattern to their distributional movements. But they all appear to be in good body condition. We are getting good documentation of the condition of the new calf frequently for assessment.”
“Orcas in Our Midst”
Howard Garrett of Orca Network has updated his 33-page book “Orcas in Our Midst.” Volume 3 is dedicated to J-1, known as Ruffles, by far the oldest male among the Salish Sea killer whales when he went missing last fall.
Howie explains the natural history of killer whales in the Pacific Northwest and their evolution from land-dwelling creatures, as he delves into the cultural aspects of killer whale society. A special focus in this edition are the differences between resident and transient killer whales.
Howie and I recently discussed our mutual curiosity about killer whale culture and what researchers are discovering. As he noted:
“We’re seeing a new global awareness, an understanding that there is not just one orca. There are many, many forms around the world. How did that come about? How do they get their own identity, and how do they maintain that?”
At just 33 pages, one might consider this a basic book about killer whales — and it is — but Garrett has a knack for taking side trips that give you a sense of the complexity of this topic while hinting at the questions yet to be answered. To order the book, go to Orca Network’s Web Shop.
Who’s the daddy?
You may have read one of the recent news stories about how Southern Resident killer whales occasionally mate within their own pods, unlike Northern Residents of Upper British Columbia, which almost always breed outside their own pods.
We’ve always known the moms, because their offspring stay with them for life. But the dads are another matter.
It was previously believed, for example, that males in J pod would mate with females in K and L pods, but not those in J pod. The latest findings conflict with that view and bring up many questions.
Because of the small population size of the Southern Residents, the new study raises concerns about inbreeding and the extent of the genetic bottleneck. At least, the researchers found, Southern Residents do not mate with close relatives, as might be the case with a few bottlenose dolphin groups.
Michael Ford, who led the study for the National Marine Fisheries Service, told reporter Craig Welch of the Seattle Times that since the whales occasionally breed outside their pods, the population does take advantage of the larger gene pool:
“In terms of how bad it is … that depends on how long the population size stays small. Brief bottlenecks don’t necessarily have to have a long-term impact. But as a general rule, we should be concerned about small population sizes because genetic diversity is the raw material for adaptation and evolution.”
Of the 12 identified paternities, five involve mating between J-1 and a female in J pod. J-1, who disappeared last fall, was the oldest male around. The evidence suggests that older males are more successful reproductively, and J-1 may have been the most successful of all. The researchers could not conclude whether the apparent success of older males is the result of dominance over younger males, a selection by their female partners or a combination of factors.
With J-1 out of the picture, it will be interesting to see whether the frequency of intrapod mating declines.
Other info: News release (PDF 72 kb) from National Marine Fisheries Service.