J50, a southern resident killer whale that was featured much in the news lately, was instantly recognizable by the scars on her back, and many people attributed them to having a difficult birth. It was speculated that a family member may have acted as a “midwife” by physically pulling her out of the birth canal with their teeth.
J50′s extensive scarring. Photo by Gary Sutton.
She is not, however, the only calf to have been documented with scars at birth. AB37, pictured at the top of this post, was a Southern Alaska resident killer whale born to AB6. AB37 was photographed shortly after birth with extremely severe scarring, even more prolific than J50′s. There was not much to be said about AB37 and her scars apart from the short description in the book “Killer Whales of Southern Alaska.” AB37 unfortunately was a likely victim of the Exxon Valdez oil spill as she disappeared soon after the spill at the young age of 3. Her entire family is now deceased, many of them also being lost to the oil spill.
Might these scars be evidence of true killer whale “midwifery?” It’s virtually impossible to know. A killer whale birth has never been closely observed in the wild. The recent discovery of infanticide in transient killer whales has brought up the possibility that these scars are not necessarily from a family members aiding in a birth but actually something more far sinister. While infanticide hasn’t yet been observed in resident killer whales, it’s entirely possible the scars on these infants are in fact the result of marauding males attempting to kill them in order to force their mothers back into estrous so he could father calves instead of his rivals. Or perhaps these scars are from something else entirely that we still have yet to discover.
One thing is certain: the first moments of life for these tiny whales were full of mystery and difficulty.
In the foreground of this photo are members of AP pod, including AP11, AP4, AP4′s calf, and AP8. I know these whales well and have seen them countless times. In the background, however, are whales that are unfamiliar to me. They have not been documented in the killer whale photo-identification catalog for Alaska. I have seen some of these whales on a few occasions, but they have always defied recognition. We do not know where they come from, where they go, or how they fit into the southern Alaska resident killer whale population.
AP9 is an adult male killer whale in the southern Alaska resident population. Because AP pod was only recently cataloged, his year of birth is unknown. Based on his growth patterns he is likely around 20 years old (give or take a few years).
While not the best photo (thanks autofocus!), this snapshot shows a very cool behavior that is observed in killer whales called alloparenting, and more informally, babysitting!
In this photo we see adult male AP18 in the background with a younger juvenile, probably around 3 years old, in the foreground. This calf belongs to AP3, a reproductive female in the pod (and has not been assigned a formal alpha-numeric designation by researchers yet). When I was documenting the whales during this encounter, I noted that AP3′s calf was not with her. I became worried as I had just seen this calf a week prior. Then, the massive male AP18 showed up with the calf in tow! She was zipping around AP18 (who is probably either her brother or uncle) while her mother lazily followed her from behind several hundred yards away.
Studies on social behavior in male resident killer whales show that males often “babysit” their younger relatives. Mother killer whales may pass off their youngsters to their brothers or sons in order to take a break. Raising a calf is energetically costly to a mother. Calves are bouncy, energetic, and like all kids, don’t want to sit still when mom needs a break. By handing her calf off to a relative, the mother can gain some much needed rest.
What do the males gain in return? The males may receive inclusive fitness benefits by babysitting their younger siblings and nieces/nephews. There is some evidence that when a female has available alloparents, she may be more reproductively successful. Males stand to benefit from their female relatives reproducing frequently as this also spreads some of their genes around (and in the eyes of evolutionary biology, the ultimate driver of all behaviors is the passing on of genetic information).
Rose, Naomi A. 1992. The social dynamics of male killer whales, (Orcinus orca), in Johnstone Strait, British Columbia. Ph.D. dissertation, University of California, Santa Cruz.
What a difference 6 years makes! When the North Gulf Oceanic Society snapped AD11’s last official ID photo in 2012, he was still a juvenile and was not distinguishable as a male or female.
Now he’s all grown up! Based on his size, AP11 is probably between 15-17 years old. Male killer whales go through a rapid period of growth called “sprouting” when they are about 12-13 years old. During this growth spurt, their dorsal fins increase in height, their pectoral flippers broaden, tail flukes start to curl, and they gain a huge amount of weight and bulk.
He still has some more growing to do and won’t be completely physically mature until he’s about 20.
The past 2.5 months held the best whale encounters to date. We saw a total of 5 different resident killer whale pods in Kachemak Bay and I was able to collect a ton of important data. Now it is time for me to finish my last year of undergrad; by this time in May, I will have my degree, and will be able to officially call myself a marine biologist.