Killer culture - divergent killer-whale cultures

It's dinnertime for the killer whales. Unhurriedly, the 28 members of the pod skirt the edges of a school of coho salmon, gradually forcing the fish into a closely packed mass and assuring the whales an easy catch. As they work, the whales "talk" volubly among themselves, seemingly exchanging information. * Twenty miles to the south, the dinner bell has also rung for another, much smaller group of killer whales. Their hunt is different from that of the salmon eaters. These orcas are quietly approaching a basaltic shelf used as a resting place by Steller's sea lions. The seal hunters disdain fish; they kill and eat only marine mammals. They travel alone or in twos or threes rather than in the large, freewheeling aggregations that characterize their salmon-eating kin. And they are usually laconic. They never speak at all while hunting. What conversation they do have is reserved for the moments during and just after the kill, when the spoils of meat are divided among the group.

The differences between these two groups have led researchers to believe that the life of the killer whale - Orcinus orca - is a complex one, based on traditions and cetacean-style family values. Apparently these whales exist within the context of a genuine culture - or more appropriately, cultures. "Orca societies are in no way similar to human societies, but they are societies nevertheless," says whale biologist Ken Balcomb.

This view has taken shape gradually over the past 20 years as researchers have gathered more and more information on the killer whale populations of the Pacific Northwest. Their data are of essentially two types: photo identification of individual whales, and underwater recordings of the sounds they make. Orcas may look alike to the layperson-black with a white belly patch extending up the flanks, a white patch behind the eye and one behind the dorsal fin, and a body up to 30 feet long that weighs in the neighborhood of five to six tons - but individual differences are obvious to the veteran researcher. "The shape and condition of the dorsal fin and the size and shape of skin patterns vary from whale to whale," says Balcomb. "When you examine photos, each whale looks very distinctive."

Just as photos have allowed Balcomb and his fellow researchers to follow the lives of individual whales, hydrophones have allowed them to document the linguistic and aural lives of the various groups. Together these two approaches have helped lead researchers to the conclusion that two separate populations of killer whales inhabit the waters off British Columbia and southeastern Alaska, populations so different that they are essentially like different species.

Field observers have dubbed the two groups "residents" and "transients," rubrics that emphasize their most distinguishing characteristics. Residents, the homeboys of the orca world, demarcate well-defined ranges, in which they follow and herd five separate species of salmon. Transients, by contrast, are free-ranging nomads; they cruise far and wide along the western coast of North America, taking harbor seals, sea lions, porpoises, and other whales where they find them.

Balcomb's specialty is the residents, and he lives in an ideal venue for their study. He works at the Center for Whale Research, which is located on San Juan Island, just off the coast of Washington State. Perched on the rocky shore of Haro Strait, in between San Juan and Vancouver islands, the site offers a clear view of hundreds of square miles of protected inland waterway. Hydrophones sunk offshore allow Balcomb to hear the whales coming; their squeals and squawks can be picked up while they are several miles away. During the summer, when the chinook and coho salmon are running, three separate pods of whales (a total of 96 animals) breeze by with almost metronomic regularity. In all, 19 different resident pods inhabit the near-shore waters that run from the San Juan Islands to the tip of southeastern Alaska some 600 miles away. "It's taken us years," says Balcomb, "but we've identified every separate pod of resident orcas, and every individual within a pod, here in the San Juans and in the Strait of Georgia, which is just to the north. And we've learned a tremendous amount about their social interactions."

A salient characteristic of a resident society is its matriarchal structure. Orcas are shy breeders. They reproduce slowly, averaging one calf every eight years (a total of fewer than 2,000 orcas are thought to inhabit Alaskan and western Canadian waters). But the resident calves that are produced stick around. "Sons and daughters stay with the mothers through their entire life span of 40 to 80 years," says Balcomb. "That's very rare in the wild." And when the pod grows to an unwieldy size, it splits matrilineally. "You end up with groups of whales that live as extended families, with females at the top of the hierarchy."

Residents also distinguish themselves by sticking close to areas where food is known to be plentiful; salmon are reliably found in certain parts of the ocean at certain times of the year, and whales that consistently hunt those parts assure themselves of food.

Most significantly, though, resident orcas are loquacious. Their vocabularies are among the richest in the cetacean kingdom. "Contrary to popular belief, not all whales vocalize extensively," says marine mammal scientist John Ford of the Vancouver Aquarium. "For example, most baleen whales, with the exception of humpbacks, are fairly quiet." Of the cetaceans that have been studied, well-defined vocalizations seem to be the exclusive province of toothed whales like the orcas, along with dolphins and humpbacks. Not surprisingly, perhaps, the talkers seem to be more intelligent than the nontalkers.

"Many baleen whale species, which vocalize very little, don't appear to be that bright," says Marilyn Dahlheim, a researcher with the National Marine Mammal Laboratory in Seattle. "Gray whales, for one, seem to be about as smart as cows." Of course, she says, it's hard to equate vocalization with intelligence, and who's to say cows are not intelligent? After all, it's not that the krill-eating baleen whales are particularly stupid; it's just that they are only as bright as they need to be. "Most baleen whales feed on species they can forage for, and they don't need a great deal of acumen to track them down," says Ford. "But you have to be pretty smart to hunt a seal or a porpoise."

By this reckoning, the relatively high IQ of the humpbacks makes sense. Unlike other baleen whales, humpbacks feed heavily on small fish such as herring and sardines. They capture them with their own version of a fisherman's net. Several humpbacks will join forces to compress a school of fish by blowing streams of bubbles around the school's periphery. When the fish are packed tight, the whales dive into the middle of them with jaws agape. The cooperative action necessary for such foraging behavior presumably requires more intelligence than the vagrant straining of the seas for krill as practiced by the gray, blue, and other baleen whales.

Orcas and humpbacks, then, are among a handful of species that have been "unleashed from the restraints of genetics," as Ford puts it. They have developed the specialized organs and brain structures that make vocal learning both possible and useful. Researchers disagree over whether the sounds and songs produced by orcas and other whales constitute an actual language. But Ford believes they do, at least for orcas, although he cautions that orca vocalizations don't begin to approximate human speech in complexity.

"Only humans, macaque monkeys, and some whales and seals can learn, reproduce, and even modify sounds," he says; some researchers, he notes, would include certain bird species as well. Yet orcas not only have language - they have dialects. Ford has determined that each resident pod speaks a lingo that's distinct even from the language of other pods living nearby. Dialects are evidently determined by family roots rather than geography.

Ford has identified several calls that have specific meanings for each of the resident pods off the San Juans and British Columbia. "We divided the pods into different clans based on our identification of their dialects," he says. "We believe that some pods have close consanguinity with other pods and share some of the same calls. But pods that we think are more distantly related use different calls in any given circumstance."

The concept, he says, is analogous to human language. "One clan, for example, may use orca Romance languages - different pods speak Spanish, Italian, or French within the larger clan context. But another clan is, say, Chinese, and different pods within the clan may speak Cantonese, Mandarin, or some other dialect."

By recording and comparing different calls, Ford has found that within a single pod, each call will have a specific acoustic pattern - one call may consist of three warbles with an overall rise in pitch, then an abrupt drop-off at the end. In a related pod, that same call might maintain the three warbles and the rise in pitch but be missing the drop-off. Ford also suspects that the two characteristics unique to resident orcas - possession of dialects and the matriarchal structure of the pods - could be linked. Because sons and daughters remain with the mother's pod their entire lives, the danger of inbreeding should exist. Different dialects may allow the whales to identify different lineages for the purpose of mating.

Residents within any given pod average 12 different calls, all of which may vary in duration and pitch depending on the whales' activity. When they are associating with whales from other pods, for example, the animals become excited. Then their calls become more frequent and varied, and they tend to be pitched higher. "You can tell their mood right away," says Ford. "Their emotional state seems to be encoded in sound more than anything else."

Residents also freely use echolocation to find their prey; these sonar clicks are clearly distinct from the lilting trills and squeaks that constitute their social interactions. "No one knows if any of the orcas form an actual image in their brains from their echolocation signals," says Robin Baird, an orca researcher from Simon Fraser University in Vancouver. "We don't know as much about orca echolocation as we do for the smaller dolphins. But certain dolphins can discriminate between objects of different sizes and compositions to a very fine degree. Since orcas echolocate for the same purpose as dolphins - to find food - it's likely they share similar abilities."

But while all orcas echolocate, not all do it to the same degree. "Residents often echolocate in a long series of clicks," Baird says. "They're probably getting very detailed pictures of the salmon schools." It's a different story with transient orcas. They, too, possess the ability to echolocate, but they rarely use it. "And when they do," says Baird, "it's usually in single clicks." The difference between resident and transient echolocation behavior may stem from the different diets of the two groups. Marine mammals - the prey of choice for the transients - may become alarmed by the sound of incoming echolocation, so the transients may have learned that a silent strategy works best for hunting.

Certainly some marine mammals seem able to tell which orcas are a threat. "Harbor seals are the main prey for transients around the southern island," says Baird. "Many of the seals show only mild interest when residents swim near them, but they become noticeably alarmed when transients come into the vicinity."

While transients may have learned to be quiet during a hunt, they do talk extravagantly once a kill is under way. "They vocalized tremendously during a gray whale kill we witnessed," says Sean Van Sommeran, the operations director of the Pelagic Shark Research Foundation in Santa Cruz, California. "The orcas killed the gray by drowning and buffeting it. They hit it with their flukes, and they bit the pectorals and pulled it underwater so it couldn't get air." After the kill, Van Sommeran witnessed mothers escorting their calves to the carcass to deliver a few fluke blows. "Sometimes the young ones would miscalculate the blows, flip completely out of the water, and land on the carcass. I think it's the kind of technique that takes considerable practice to perform correctly." And through it all, says Van Sommeran, the whales were extremely noisy.

Still, such calls may be akin to simple war whoops or cheers; transient vocabularies are truncated compared with those of the residents. It appears they use no more than half a dozen distinct calls, a kind of pared-down "hunt language." Their language is uniform too, with only a single dialect spoken from Alaska's Glacier Bay as far south as Los Angeles. "The transients probably don't need as many calls as the residents to define their social interactions," says Ford. "They travel in smaller groups, the young don't always stay with their mothers, and they don't stay and hunt in a particular area. There just isn't as much long-term stability in transient groups, so their languages haven't had a chance to evolve."

Research on transients is not as advanced as it is on residents, chiefly because transients move around a lot and are hard to find. Yet Van Sommeran believes it's logical to assume they repeatedly visit certain hunting locations where they've had success. "We think they show up at specific places at specific times of the year when they know marine mammals will be abundant," he says. "One month they'll be in Monterey when the gray females are crossing the bay with their calves, another time they'll head to a rookery when seals or sea lions are having their pups." Other researchers aren't so sure that transients shadow migrating pinnipeds and whales the way lions shadow migrating wildebeests in Kenya, but all acknowledge that their range is impressive. Dahlheim has shown that the North Pacific transients range from Alaska to at least central California and probably farther south.

Transients and residents are distinct biologically as well as culturally, though no one is yet ready to declare that the two groups constitute different species or subspecies. "We've documented small morphological differences very well," says Balcomb. "Residents have definitely evolved rounded dorsal fins, while transient dorsals are quite pointed. And the white dorsal saddle patch goes forward much farther on the transients than on the residents."

Recent mitochondrial DNA tests conducted on captive transient and resident killer whales from the Vancouver Island area indicate that genetically, the transients are as different from the local resident whales as they are from orcas in the North Atlantic. The rather loose structure of transient society apparently allows ample opportunity for gene swapping between the various transient groups. But the tests conducted so far suggest that no Vancouver Island orca females have broken "social" lines to crossbreed for a very long time - for many thousands of years at least. Female residents breed with male residents, and female transients with male transients.

Which group came first? Researchers speculate that the residents were originally "seeded" from the transients: Free to range the world's oceans, the primordial ancestors of today's orcas sought seals and whales from pole to pole. In those areas where fish were plentiful and available year-round, it's likely some orcas stayed to take advantage of the bounty. And because catching fish required different social and foraging skills from those required for catching seals, new habits and new cultures evolved.

Separation between resident and transient populations occurs in parts of the globe other than the Pacific Northwest. Orcas are the world's most widely distributed marine mammals, though they are not particularly numerous in any locale they inhabit - about what you'd expect for an animal that lives at the very pinnacle of the marine food chain. "In Antarctica the situation is very similar to the one we have here," says Balcomb. "There some of the orcas subsist on a type of small, oily cod that exists in huge numbers, while other groups live exclusively on whales and pinnipeds. And each avoids the other."

Residents and transients seem to have one final behavioral difference that researchers can't help noticing: the two have radically different attitudes toward intrusive humans. Residents tolerate - even welcome - human propinquity. The photographs of kayakers lolling among orca dorsal fins commonly featured in Alaskan and British Columbian travel brochures portray resident whales. No similar photographs exist of transients, apparently because they are, at best, aloof. There have been no substantiated transient attacks on humans, but posturings that can easily be translated as aggressive are not uncommon.

"During one gray whale kill, a big male transient swam out to our boat, splashed us with water, then backed away," says Van Sommeran. "It clearly seemed as if he wanted us to keep our distance. So we did." Dahlheim also remembers a chancy encounter with a transient female off Baja after a sea lion kill. "She was with her calf and had a big chunk of blubber in her mouth," says Dahlheim. "She came porpoising right up to our boat and began slapping her flukes against the water. I'd hesitate to say she meant us harm, because I doubt I'd be here if she was determined to hurt us. But I did feel intimidated." Ford puts it more succinctly: "The more I learn about transients, the less I'm inclined to go skinny-dipping with them."

Much has been learned about the behavior of resident and transient orcas, but the researchers acknowledge that their understanding is just beginning. Indeed, some scientists think the notion of "transient" and "resident" populations may be outmoded simply because there could be more than two distinct orca societies out there in the deep waters of the Pacific Northwest.

"About a year ago we discovered a group of orcas that weren't residents or transients - we'd never seen them before," says Balcomb. "Their language was different from any we've recorded, and they were farther offshore than orcas normally are - so we're calling them the |offshore' orcas. We know absolutely nothing about them; they're a complete mystery."

Because their habits and environment make them difficult to study, orcas will most likely provide us with plenty of mystery for a long time to come. But rudimentary as it is, the information that has been collected is enough to dispel some egregious myths. Until the middle decades of this century, orcas were viewed as rapacious murderers of the deep, wont to slay gentle baleen whales and doe-eyed seals - even unfortunate humans - in obeisance to an unslaked blood lust. Later they were transformed into antic "sea pandas," happy-go-lucky cetaceans whose highest purpose in life was to turn somersaults in a pool or snap a mackerel from a trainer's hand for the delight of tourists. Neither portrait, however, is accurate.

"These are extremely intelligent animals, and they live in very sophisticated social groups," says Balcomb, who's recently been spearheading an effort to establish radio linkups with captive resident killer whales and their home pods, to see how they will react if allowed to communicate directly with one another. "We're still learning about them, but we do know they're nothing like the caricatures we've assumed them to be."

COPYRIGHT 1993 Discover
COPYRIGHT 2004 Gale Group