Unlike Granny and her giant group of salmon-eating family members, transient orcas travel in smaller packs and are known for their wily hunting abilities: They can tip a sheet of ice in order to catapult a seal into the sea, or take down a porpoise in midair…A paper published this month describes how transients in the Salish Sea can intentionally strand themselves, hauling their bodies out on land, in order to hunt seals.
…Suddenly, the whales disappeared, and a uniform ripple appeared on the water’s surface. A small seal was swimming near the rocky shoreline, and the orca family had used its massive collective bulk to send an underwater pressure wave racing toward it. A second ripple rose from the surface, and the seal, knocked off balance, disappeared. Very quickly, it was clear that the family had triumphed: Gulls circled overhead, eager to claim the bits of seal that the whales would leave behind.
This is the hunt, the daily fight of mammal-eating orcas. It’s a dance with these creatures, a constant balance of risk and reward—the more aggressive the prey, the more likely they are to be injured in the battle. While residents have to work together to hunt salmon, salmon don’t fight back. For the transients, Hafey said, every meal is a potential death match: “It’s as if every time you opened the fridge you had to have mortal combat with a turkey to get a sandwich.”
Granny and her kin are considered part of the same species as transient killer whales, Orcinus orca. But residents and transients have lived separate lives for at least a quarter-million years. They generally do their best to avoid each other, and they don’t even speak the same language—the patterns and sounds they use to communicate are completely different. Over time, each type has established cultural traditions that are passed from generation to generation. While transients’ small groups enable them to hunt more quietly and effectively, residents’ large extended families allow them to work together to locate and forage for fish. Biology isn’t destiny, but for orcas, food sources might be.
…But these island celebrities are slowly dying. 40% of the Chinook salmon runs that enter the Salish Sea are already extinct, and a large proportion of the rest are threatened or endangered. The fish that are still around are much smaller than their predecessors, forcing whales to work harder and swim more for their meals. The resident population now numbers only 74, down from 97 in 1996.
Meanwhile, the sea lion population on the West Coast, which was protected from hunting in the United States and Canada in the 1970s, has bounced back from near extinction and is close to its historic size. The mammal-eating transient orcas are thriving in part because of this boom: During the years that Tahlequah was believed to suffer a miscarriage and the death of her newborn calf, T37A birthed the five calves who now played by her side. The transient population, which in 2018 reached 349, grew at about 4% a year for most of the past decade, and is well on its way to replacing the residents as the dominant killer whale in the Salish Sea.
…Without a reliable supply of fish, the resident orcas are beginning to behave more like transients. But, unlike the transients, they can’t just start eating squid, herring, or seals—they learn from birth that fish is their only food. “They can’t change their diet”, Deborah Giles, an orca researcher with the University of Washington Center for Conservation Biology, told me. “Theoretically, they could, but I’m reluctant to say they will switch, because they have this deep, intense cultural direction from their moms not to eat that thing.” (By occupying different positions on the food chain, the residents and transients avoid competing with each other, lessening the likelihood of aggressive encounters.)
The transient orcas are changing their behavior as well, Shields told me. While they typically travel and hunt as small family units of three to five whales, she’s recently seen them traveling in groups of 20 to 40. The groups are almost like the resident superpods of years past, Shields said. Researchers have nicknamed them “T-parties.” “They’re definitely less focused on being stealthy and hunting”, Shields continued. It’s possible that mammal-eating orcas have such abundant food that they don’t need to spend as much time hunting—and can spend more time socializing.
…The residents are speaking, loudly, to anyone who is listening. They are moving away from their summer homes, searching high and low for salmon they once found with ease. They are struggling to give birth, to keep their babies alive, to keep up with a rapidly shifting world. At the same time, the transients are quietly waiting to be heard.