Social networks a key to orca survival
Understanding the social networks and family bonds of Puget Sound's southern resident orcas may be critical to keeping the endangered whales from extinction. A healthy population is about more than numbers, scientists say. It's about connections.
A boy needs a mother: A universal proposition, but one that’s even truer for some creatures than others. Take the southern resident orcas of Puget Sound. Among these whales, both males and females stay with their mothers for their entire lives – an arrangement almost unheard of in the animal kingdom.
These tightly bonded families travel together, forage for salmon together, and are rarely out of contact for more than a couple of hours. And so, when a southern resident known as L32 died in the summer of 2005, her 13-year-old son L87 went looking to fill the mom-sized hole in his life.
Soon, L87 was consistently spotted with an older female known as K7. She was born around 1910, and had two sons of her own, scientists think. But they had died years before; perhaps L87 filled an empty space for K7, too.
It wasn't to last. K7 died sometime in the spring of 2008 and the pattern continued. L87 stayed with K7’s larger social group, but in 2011 he seems to have gone looking for yet another mother figure, attaching himself to a nearly 80-year-old female known as J8.
She too passed away two years later, and L87 began swimming with J2, also known as “Granny,” then the oldest of all the southern resident orcas. Since she disappeared in late 2016, L87 has been traveling with a forty-something whale known as J17 and her multigenerational family.
L87 is one of only 75 of Puget Sound’s endangered southern resident orcas. But as his story shows, that population’s survival isn’t just about numbers, it’s about relationships. Mounting evidence suggests that understanding the whales as individuals with valuable and specific roles in their social world will be key to saving the southern residents as a whole.
“If we lose an individual whale out of the population, it’s not just that whale we’re losing,” says Monika Wieland Shields, president of the Orca Behavior Institute. “That’s going to have a ripple effect throughout their family group.”
Six degrees of cetacean
L87’s story, and the current scientific view of southern resident orca society as a whole, is the product of rapt attention sustained over the course of decades.
In the early 1970s, Canadian biologist Michael Bigg pioneered a technique known as photoidentification in his studies of killer whales off the British Columbia coast. The method is now a mainstay of research on whale and dolphin social life, and noninvasive studies of other wild species. Scientists use distinctive markings to identify individual animals – in the case of orcas, the appearance of the dorsal fin and saddle patch, a pale gray marking on the whale’s back.
Bigg and Canadian colleagues including John Ford, as well as American Ken Balcomb, applied the method to killer whales in the Salish Sea. They assigned each whale an alphanumeric code and tracked who was seen with whom over time.
Early on, this work yielded the surprising insight that Puget Sound has two entirely separate populations of orcas – the mammal-eating transients and the salmon-eating southern residents – that never intermingle and scarcely even interact. (Another group of salmon-eating whales, the northern residents, is found in Canadian waters.)
It also established that the southern residents live in family groups composed of an adult female, her offspring, and her daughters’ offspring. Several such matrilines that frequently travel together make up a pod, and three pods – J, K, and L – comprise the southern resident population.
Orca societies are matrilineal on the whole. But family bonds aren’t always as strong as they are among the southern residents. Transient males sometimes separate from their mothers and become ‘rovers.’ But nor are southern residents unique; the northern residents have a very similar social structure.
By now, there are thousands of records chronicling where individual southern resident orcas went, what they did, and with whom over the past 40-odd years.
Such studies show that overall, the southern residents are a tight bunch. “Every individual has connections with a lot of other individuals,” says Michael Weiss, a field biologist with the Center for Whale Research in Friday Harbor and a graduate student at the University of Exeter in the UK. “Even though their strongest relationships are within their matriline, they have strong connections with non-matriline pod members, and even fairly strong connections outside of the pod.”
But ecological stresses can strain and weaken those bonds. The social network is less interconnected in years when salmon are less abundant. And the three pods were less cohesive during a previous period of population decline in the mid- to late-1990s.
The latest records haven’t yet been analyzed in this way, but scientists who study the whales say they’ve seen similar trends as the whales have struggled in recent years: pods splitting up into single, pairs, or trios of matrilines, and fewer whales together at a time.
“There’s just not enough food to support them in any one area if they’re all together,” says says Deborah Giles, a killer whale biologist with the University of Washington Center for Conservation Biology and science and research director for Wild Orca.
‘Superpods,’ events in which all of the whales from all three pods come together, are also less frequent, says Orca Network director Howard Garrett. He likens these gatherings to a “barn dance,” featuring “a lot of breaching and tail slapping and rolling over and flopping on top of each other,” and “dozens of conversations going on at once.”
These days, the whales spend more time traveling and less time foraging than they did 40 years ago, suggesting they’re doing a lot of searching for food and not much hanging out and feasting. One thing that hasn’t changed: the whales spend just as much time socializing – albeit in smaller groups – as in the past.
That suggests Puget Sound might be culturally important to the whales as a meeting place, not just a foraging ground, Shields thinks. Still, fractured pods and fewer superpod gatherings could affect opportunities for mating, bonding, and information sharing throughout the population, she and other scientists say.
Large adult sons
Social network analysis is also revealing vulnerabilities for individual orcas. For example, adult males who are on the fringes of their social network are at greater risk of dying than males who are more central. And this pattern, too, is more pronounced in years when salmon are scarce.
Researchers believe this phenomenon is linked to the whales’ habit of sharing food with their social connections. Male killer whales are larger than females, and need more salmon to sustain themselves, so they’re especially reliant on shared food.
And the most important source of shared food for a male orca is his mother. The death of his mother increases an adult male’s own risk of dying by eight times for the next two years.
That finding makes L87’s surrogate-mother-seeking look like a savvy survival strategy. It may also explain the recent struggles of K25, a 28-year-old male who appeared emaciated last fall.
K25’s mother died in 2017. He has one sister with a 15-year-old son; his other sister has an 8-year-old son and is currently pregnant – so they’re unlikely to be able to share much with their brother.
“Right now he is in that danger zone,” Weiss says of K25. “I'm not really surprised that he's looking ill.” Fortunately, more recent sightings suggest that K25’s condition is improving – suggesting that he’s found his new place in the pod.
Female orcas share salmon with their adult sons often, but with adult daughters less so. For a mother orca, that investment may be a good strategy for passing on her own genes. According to National Marine Fisheries Service geneticist Mike Ford, a genetic analysis of the southern residents showed that just two of the largest, oldest males – J1 and L41 – fathered more than half of the babies born between 1990 and 2010.
“That's what we want with our males, is [for them] to get big and old,” Giles says. And family ties are key to that happening.
Females in the lead
The notion of orca families isn’t entirely a recent one. In the cosmology of the Lummi Indian Nation, whose ancestral territories include the San Juan Islands, orcas are qwe ‘lhol mechen, or “our relations under the waves.”
A ‘spiritual feeding’ ceremony in which the Lummi honor the qwe ‘lhol mechen involves placing salmon on cedar boughs in deep water to share with their relatives. When Lummi leaders performed this ceremony in January, “We had one live chinook to feed Princess Angeline, and a dead one to offer the qwe ‘lhol mechen ancestors,” Raynell Morris, senior policy advisor in the Lummi Sovereignty and Treaty Protection Office, wrote in a Seattle Times op-ed.
Princess Angeline (the name honors the eldest daughter of Chief Seattle) is also known as J17, a 42-year-old orca who was in poor condition, with the ‘peanut head’ indentation behind her skull that is characteristic of emaciation, last fall.
“One potential explanation for what’s going on with her is her family group has been hit by a lot of tragedy,” Shields says. J17 is the mother of J35, the whale who gained national attention last summer when she carried her dead newborn calf for 17 days and 1,000 miles – an ordeal that would have prevented her from foraging.
J17’s family group also includes a son and a grandson, ages 10 and nine; an orphaned 10-year-old granddaughter; a four-year-old daughter; and, of course, L87. “I can just imagine that J17 has been trying to feed these other whales, maybe at the expense even of herself – trying to keep her family members well nourished,” Shields says.
Female orcas over age 42 – J17’s age – are considered ‘post-reproductive.’ But these older females remain crucial to the survival of their families, not just as providers but as leaders. Older females are often in the lead when groups of southern residents are traveling through foraging grounds. Sons are more likely to follow their mothers than are daughters. And, again, these older females are out in front more often when salmon are scarce.
Those findings suggest that older females are keepers of knowledge that benefits the population as a whole. “If they go to a particular place at a particular time expecting to have a salmon run available to them and it’s not there, then the older females know where to go next,” Giles says.
These whales may hold other types of knowledge important to the group as well: hunting methods, parenting techniques, expertise in mediating conflict. And all that may change conservation strategies and decisions about when to intervene medically to help a struggling whale, says Joe Gaydos, SeaDoc Society science director [Gaydos is also a topic editor for the Encyclopedia of Puget Sound].
Normally, saving endangered populations means investing the most money and effort in animals that can make lots more babies – not ones like J17 at the tail end of their reproductive years. “But then when you realize how many animals are dependent on her, you think: Oh, maybe we should rethink this,” Gaydos says. “This is actually a really important animal.”
Twilight of the matriarchs
The southern residents currently have nine post-reproductive females across all three pods, but only one of them is over age 50. In the last decade, four of the population’s oldest females have died – whales in their 80s or 90s like L87’s foster mothers K7, J8, and J2.
That’s concerning because the whales with the longest memories likely hold the largest stores of ecological knowledge. “You want to preserve those information archives in the oldest animals. You also want to maintain enough diversity in information so that they can respond to environmental change,” says Kim Parsons, a marine biologist working as a contractor with the Northwest Fisheries Science Center. “The survival of the youngest often does depend on the survival of the oldest.”
Some scientists suspect that losses of older females (nine younger matriarchs have also died in the last decade) could be contributing to the fracturing of the southern residents’ pod structure. “Maybe it’s not just searching for food, but the older females are the glue that holds the group together,” Shields says.
The distribution of older females might also help explain why lately, matrilines from different pods even link up and travel together for a season or two. “Is there something about the group composition – ‘Hey, we don’t have an elder female in our group so we want to travel with your group that does have one?’” Shields says.
The answers to those questions aren’t yet clear. Weiss and others are analyzing how southern resident social networks change after the deaths of post-reproductive females.
But scientists who pay close attention to the southern residents can see that something has changed. “When [J2] would want everybody to go a particular way, she would just slap her tail on the surface of the water. And you could see whales from literally miles away come directly to her side,” Giles recalls – not just whales from her own J pod but Ks and Ls as well.
“I don’t know that you would see that. I personally haven’t seen that with any individual southern resident killer whale since J2 died.”