Then, etched at the edge of visibility, the first black-and-white heads appear, darting towards me, peeling off at tangents, transforming the water into an animated labyrinth of sleek striped bodies.
Drawn by their tightly choreographed dancing I dive down, twisting and spiralling in imitation as they circle around me, tilt their heads and level their large black eyes at mine.
A trio of quivering beaks emit a cascade of clicks which scan the surrounding ocean, speeding up as they zero in on my body. I revel in the blast of white noise that crackles like an excited Geiger counter, sensing the hollow cavern of my lungs and the solid orb of my head.
I have entered their world, an acoustic universe as sensitive and nuanced as ours is visual. Here a dolphin’s head acts as a living sonar system, a kind of ultrasound scan that sends out simultaneous signals on different frequencies, and enables the animal to build up an acoustic map of its environment, communicate with the rest of the group and, possibly, stun its prey.
I call to them through my snorkel. What they make of such garbled sound I don’t know, but the more inquisitive ones begin to sprint in tight circles, forcing me to spin on my axis to keep eye contact. They are so close now I can reach out and touch them, each one unique down to the nicks and scars on its fins.
My lungs ache for air, and the pod of duskies begins to move away. I long to swim after them, deeper into that emerald city, but there’s an urgent oxygen debt to be paid at the surface. I burst back into the sunlight, suck in a deep breath and look around. Nearby, watching from his runabout, is skipper and local tour operator Brent McFadden; in the distance, the duskies’ curved backs are rhythmically cresting the swells—a gentle finale to today’s mercurial “symphony of the dolphins.”
Kaikoura is dolphin Riviera. Here nutrient-rich water from the Southern Ocean rises close to shore, supporting massive plankton production and offering a banquet of kahawai, mackerel and squid to the cetaceans (whales and dolphins) which gather offshore.
Here the commonest cetacean species, and the most acrobatic, is the dusky dolphin. Duskies are southern hemisphere dolphins which frequent areas that are cooled by circumpolar currents: the southern tips of America, Africa and Australia, as well as New Zealand from East Cape southwards. They are medium-sized dolphins—up to two metres in length—and have particularly striking faces: a short thick black snout, grey-black eye patch and mouths that look like a pair of smiling pursed lips pushed up towards the eyes by the neat symmetry of their white chins.
Like most oceanic dolphins, duskies feed co-operatively. As they travel, they scan the sea with their echolocation apparatus. When they find a school of fish or squid, they work together to corral the prey into a tight “meat ball,” before taking turns to move in and feed. Some individuals patrol the perimeter of the school, leaping and belly-flopping and flailing the surface of the water with their tails to keep the school together. Others swim below, shepherding the school upwards and using the sea surface as a wall against which to imprison their prey. All the time the dolphins maintain a steady stream of clicks—the equivalent of keeping in radio contact with each other.
North American dolphin expert Professor Bernd Wiirsig has been studying Kaikoura’s dusky dolphins for 20 years, and has found that the animals follow definite patterns of feeding, resting and playing. Usually a short burst of intense feeding activity in deeper water is followed by rest and play in the shallows, where it is easier to avoid attack from below by predators such as orca (killer whales) and sharks.
Much can be learned from the type of leaps the dolphins use, says Wiirsig. Clean, head-first re-entries and “body-slams” indicate feeding, but the highly acrobatic spinning leaps so admired by dolphin-watchers are reserved for playtime, when the dolphins have games of catch and toss with seaweed, interact with turtles or birds, or indulge in recreational mating.
I see this behaviour for myself one morning at Kaikoura. On our way out to the feeding grounds we are met by a small party of five duskies knifing through the oily swell, their svelte forms silhouetted against the rising sun. Several males are courting a female, amorously vaulting in synchronised arcs over her head, and often nearly colliding with each other in their enthusiasm. The female leads the group back and forth in a wide zig-zag path before choosing her mate; together the two glide down into the water, belly to belly.
Leaving them to their nuptials, we speed on to where a larger pod is feeding. A flock of terns wheel and dart overhead, picking up bait fish. I hang over the bow watching the wave-riders, their whistles clearly audible out of the water. In amongst the duskies I notice a group of common dolphins, easily identified by their distinctive bronze blaze and criss-cross markings. Sleek and streamlined, with a long beak and tapered flippers, common dolphins are about the same size as duskies, but are usually lighter (an average weight of 80kg as against 115kg). They have a thin black bridle running between black eye patches above the purple hue of the beak and lips. As their name implies, they have a worldwide distribution.
Two other boats pass us, loaded with eager dolphin swimmers. They are on a high, calling to the dolphins who seem to have brought out the child in us all. One curious dusky bobs up, half out of the water, “spy-hopping” for a closer look at the assembled flotilla, and is quickly met by a battery of camera shutters.
Dolphin encounters like these, once a fringe form of eco-tourism, have transformed Kaikoura into a backpacking boomtown. Since swimming permits were first issued in 1991, the demand for in-the-water dolphin contact has increased markedly, and this summer some 35,000 tourists—mainly young Europeans—have visited Kaikoura for the dolphins and whales.
Photographer and cofounder of Kaikoura’s Naturewatch Tours Barbara Todd began offering swims with dolphins at the request of her whale-watching customers. While agreeing that dolphins and humans seem to have a mutual fascination one for the other, she believes many people project their preconceptions on to dolphins—seeing their exuberant acrobatics as performances for their human audiences. Not so, says Todd. Leaping is as much a part of normal dolphin life as pronking is in antelopes, or frolicking in baby lambs. Todd herself prefers to think about the way dolphins may be regarding us: “With our lifejackets and cameras we probably look to them like funny orange blobs, with one big eye that clicks.”
Todd has seen many unusual sights on the water: duskies playing with seals, sperm whales and other dolphins, and, most eye-opening of all, interspecies copulation between duskies and commons, and commons and bottlenose dolphins. (Successful mating between species has been recorded in captivity, but, as with horses and donkeys that breed, the offspring are usually sterile.)
To human eyes, dolphins appear highly promiscuous animals. Adults do not form pair bonds, and even the very young members of a school practise courtship and mating behaviour. Much of this activity appears to be non-reproductive, as it takes place outside of the peak period of conception, and dolphin researchers consider it to be part of a continual process of building and maintaining communal relationships within the pod.
Dolphins have a low reproductive rate, usually producing a single calf every 2-3 years. Gestation lasts 10-12 months, and rearing up to two years. With a life span of around 20-50 years, dolphins bear their first calf between five and 12 years, depending on the species.
Calves are usually born tail-first, with the mother biting the umbilical cord (if it hasn’t already broken) and helping the calf to the surface for its first breath. Dr Alan Baker, director of the National Museum and author of a dolphin identification guide for New Zealand and Australia, describes a typical birthing scene he observed in a common dolphin in the Bay of Islands: “There was a commotion in the water, with lots of spray and flapping, and about 20 attendant dolphins whistling and standing guard around the mother.”
The presence of “midwives” is normal in dolphin society. They may physically support the mother from below if she is in need of help, and will often stay in attendance and “baby-sit” the calf while the mother feeds during the first few months after the birth.
At Kaikoura, dusky dolphins begin to congregate in shallow inshore waters in mid-October, and give birth from November through to January. The mothers and calves break off from the main herd to form separate nursery groups which are matriarchal—adult males appear to play no part in rearing. The primary bond in the herd is therefore between mother and young, the calf being dependent on her fatty milk during the 18 months to two years that it will spend in the nursery.
Calves stay close to their mothers for the first months of their life, swimming alongside and often touching them with a flipper. A mother will assist a distressed calf by supporting it with her head or back, and it is perhaps this nurturing reflex that is behind the many reported cases of dolphins assisting human swimmers in distress.
Sex and age segregation have been observed in a number of dolphin species, but generally dolphins live in mixed, fluid groups with no single leader, and different members take turns to steer the group’s course.
Common dolphins are a possible exception. This species, which may form groups of several thousand, is thought by some researchers to have a more defined hierarchy, with dominant animals defending vulnerable members and reproductive females.
New Zealand’s well-placed slivers of land span subantarctic and subtropical latitudes and are home to 15 of the world’s 60 dolphin species, including both the world’s smallest and largest species.
As well as the demonstrative common, bottlenose and dusky dolphins, there is the endearing Hector’s dolphin (known only from New Zealand waters), the larger orca and pilot whales, and more obscure occasional visitors such as the Risso’s, hourglass, striped and spotted dolphins.
For most people, whether cruising in the Marlborough Sounds or fishing in the Hauraki Gulf, the most likely place to see a dolphin in the wild is riding the bow wave of a boat—an activity dolphins have been engaged in ever since there were bow waves to ride. Writing in his Historia Animalium in AD 70, the Roman poet Pliny the Elder attributes superhuman speed and agility to the common dolphin: “It is swifter than a bird and darts faster than a javelin . . . They shoot up like arrows from a bow in order to breathe again .. . and leap out of the water with such force that they often fly over a ship’s sails.”
Herman Melville digresses from describing his Great White Whale to remark, “If you yourself can withstand three cheers at beholding these vivacious fish, then heaven help ye; the spirit of godly gamesomeness is not in ye.”
The dolphins’ earliest aquatic ancestors, by contrast, would have elicited few cheers. Palaeontologists believe that the protodolphin was a derivation from wolf- and otter-like land mammals, and that it first took the plunge fifty million years ago, when much of the earth was covered with lush tropical swamp, and shallow equatorial seas were advancing over the coastline. These archaeoceti, as they are known, had elongated bodies, long tails, reduced hindlimbs and paddle-shaped front limbs, but they were probably little more elegant in the water than the plesiosaurs and icthyosaurs—marine dinosaurs—which had died out some 15 million years earlier.
Temperature changes in the world’s seas, continental shifts and the creation of the Antarctic circumpolar current all accompanied the emergence of the primitive odontoceti or toothed whales (the group to which dolphins belong) as well as the larger mysticeti or baleen whales from this archaic group. Over time, the long mobile neck. hindlimbs and pelvic girdle of the archaeoceti receded in favour of a more streamlined body shape, dorsal fin and tail flukes.
Fossils of three living dolphin groups, the Delphinidae (true dolphins), Phocoenidae (porpoises) and Monodontidae (narwals and white whales), show that today’s dolphins first appeared on the evolutionary stage around ten to fifteen million years ago, competing with giant prehistoric penguins and sharks for supremacy as marine predators.
In common parlance, there is often confusion between the names “dolphin” and “porpoise,” and many people use them interchangeably. Historically, porpoise comes from the French “porc poisson” or pig fish, while dolphin is from the Greek “delphis”, which means womb. (Dolphins frequently appeared in Mediterranean creation myths where, along with women and various “womb monsters,” they symbolised new life and regeneration.)
Biologists, however, distinguish porpoises from dolphins by the fact that they have no beak, are generally smaller and “chubbier” than dolphins, and have fused vertebrae and spade-like, rather than peg-like teeth. Present-day dolphins’ speed and agility—all the more impressive when you consider that water is 30 times denser than air—has been achieved by superb adaptation to the aquatic medium. The skull has been telescoped to allow the jaws to extend forward, and the nasal opening has moved to the top of the head. Neck and shoulders have gone, and the flippers, which have a similar skeletal structure to the human arm, have paddle-shaped, flattened “fingers” for steering and stability. Hind limbs have all but disappeared, leaving a boneless and horizontal tail propelled by four massive blocks of muscle. The similarly boneless dorsal fin provides stability and some degree of temperature regulation.
To further reduce drag, dolphins have lost all body hair, and external ears have been replaced by two minute openings on the side of the head, leading to the hearing organs.The teats and genitals have been similarly retracted inside muscular folds in the belly.
Because they feed on fast-moving fish and squid, dolphins must be able to shift from a cruising speed of around 9-17 kilometres per hour (5-9 knots) to chase speeds of up to 40kph (20 knots) over short distances, a feat often augmented by bow wave riding and repeated arcing leaps known as “running.”
Recent research in Hawaii has shown that dolphins may use bow wave riding as a kind of energy-efficient hitch-hiking. By keeping the body motionless and using the tail flukes as hydroplanes, dolphins are able to use the force of the wave to propel them with minimal effort. Experimental results indicate that for the same energy output, dolphins on a bow wave can double their normal cruising speed. (On the other hand, maybe they do it just for fun!)
The dolphin’s evolutionary redesign also extends to the skin and blubber. Living entirely in the sea, a dolphin might be expected to have a waterproof skin. In fact, it is waterlogged. And, unlike human fat, the blubber is not rigidly attached to the underlying muscle. Like a living swimsuit, the dolphin’s skin is moulded by the water conditions to form small temporary ridges, dispelling turbulence and reducing drag.
Adult bottlenose dolphins can dive to 500 metres for up to seven minutes, while the largest dolphin, the orca, can go down to a kilometre. Being air-breathing mammals, dolphins naturally have to hold their breath when diving, just as we do. This presents any mammal with a problem. Under the compression of a dive, the nitrogen in air dissolves into the body’s fluids and tissues. On the way back to the surface this dissolved nitrogen may re-form as bubbles in the tissues and blood, causing the potentially fatal condition called the “bends.”
Dolphins avoid this problem by absorbing and storing oxygen in their muscles while on the surface. They only dive with small amounts of air in their lungs, and the lungs collapse under the pressure of the dive, forcing the air into the animal’s nasal passages where no nitrogen can be absorbed. Furthermore, the dolphin’s lungs are richly supplied with very fine capillaries, and it is thought that these allow the dissolved nitrogen to rapidly return from the blood into the lungs without bubbling.
On the surface, dolphins can empty and fill their lungs in a fifth of a second, exchanging 80-90 per cent of the lungs’ stale air with a fresh intake. Humans exchange only 30 per cent with each breath.
Speed and agility aside, it is the dolphin’s finely tuned acoustic system that stands out as its most remarkable adaptation to the marine environment—a world where sound travels almost five times faster than in air.
The sensory equivalent of our eyesight, a dolphin’s echolocation system is based on the sending and receiving of ultrasonic clicks which sometimes reach frequencies of 220kHz. The sounds are thought to be generated in the nasal passages behind an organ called the melon, a waxy oval-shaped mass in the dolphin’s forehead that focuses the clicks into a narrow beam and projects them forward.
The returning soundwaves are picked up and passed along oil-filled sinuses in the lower jaw, eventually reaching the inner ear, from which a three-dimensional acoustic picture of the contours and density of the surroundings is formed.
The time lapse between the outgoing click and the incoming echo gives the dolphin an idea of distance from an object, while variation in the strength of the signal on the two sides of its head enables it to assess direction.
Dolphins produce two types of sound: pulsed clicks used for echolocation (these can be produced at a rate of more than 100 clicks per second), and unpulsed whistles, squeaks, buzzes and yelps, which carry further, and are used in group situations during feeding, courting,playing, excitement, distress, and as a personal acoustic signature.
Dolphin sonar is a highly sophisticated sense, able to track multiple objects simultaneously, and “see” in three dimensions. Echolocation experiments have shown that dolphins can distinguish between solid and hollow spheres. So, like hospital technicians using an ultrasound scanner, Kaikoura’s duskies can probably tell whether a nearby human swimmer is pregnant, and, from examining her muscle tension, may even know whether she is relaxed, frightened or exhilarated to be in the dolphins’ domain.
With all these impressive abilities, it is little wonder that dolphins have been revered from classical Greece to the contemporary Pacific, where some cultures believe that they embody transmigrating human spirits. Maori have a special regard for dolphins (tepuhi or aihe), often linking them with taniwha—spiritual beings which inhabit the seas and waterways of Aotearoa.
Sun rise splashes the sky orange over Akaroa Harbour, and our eyes are peeled for tell-tale fins breaking the mirror water. A little over a metre long, and ghostly grey, a group of six Hector’s dolphins come barrelling up to the boat from astern, their clear white underbellies shining through the murk like gleaming teeth. They draw level, peer up at us like playful children out for a game of tag, then dart past with vigorous bursts of their powerful flukes.
One juvenile dolphin swims next to us upside down, tail-slapping the surface, while further ahead a small group surf in on a swell. For the next half hour we are in the middle of a dolphin party. Hectors of all sizes surround us; a main group cruises alongside in a whooshing, panting chorus, while from time to time mavericks from outside dart into the herd and peel off with followers at high speed.
Many are characterised by nicks and tooth rakes on their flanks and fins—the result of playful jousts. Such mock aggression also includes “pouncing,” where one dolphin will literally jump on another as it surfaces. Real tooth-baring aggression is momentary and rare, and the recipient does not retaliate, but flees rapidly. Hector’s dolphins seem to live by the maxim “Retreat is the best line of defence”—perhaps a wise move for a small dolphin whose main predators are sharks.
Hector’s dolphins are found only in New Zealand, and are the world’s smallest (maximum size 1.5m) and probably rarest oceanic dolphins. Out on the water their most recognisable trait is a rounded dorsal fin—all other New Zealand dolphins have crescent-shaped dorsals.
Named after Sir James Hector, a nineteenth century curator of the Colonial Museum in Wellington, the species is most regularly seen around South Island coasts. A few are seen off the North Island’s west coast, with only very occasional stragglers elsewhere.
Otago University biologists Drs Stephen Dawson and Elisabeth Slooten have become synonymous with Hector’s dolphins research since they began their pioneering population studies on the species in 1984. Their anatomical research, exhaustive acoustic work and projects on behaviour, population and the impacts of pollution and set-netting have all received international recognition from bodies such as the International Whaling Commission.
Much of this work has been done on a shoestring budget. In 1984 Slooten and Dawson converted their old VW Kombi into a mobile home and travelling lab for $100. Trailing a rubber dinghy behind, and depending on sporadic cheques and food parcels from their parents, they set out on an 8400km dolphin-counting odyssey.
The result was a population estimate of 3-4000 Hectors for the whole country. For the stretch of coastline between Motunau and Timaru, they estimated 740 animals. But by 1988, some 230 of those dolphins—more than a quarter of the resident population—were estimated to have drowned in set-nets, sparking fears that Hector’s dolphin could be on the road to extinction.
Given the animals’ sophisticated sonar apparatus, the two biologists were at first puzzled as to why the dolphins could not detect the nets and avoid them.
After further investigation they concluded that Hector’s dolphins periodically switch off their echolocation systems in familiar waters. Even with the system on, in the heat of chasing prey they may fail to detect the monofilament nylon set-nets used by local fishermen. Besides, if they do detect a net, it may not be interpreted as a lethal obstacle. Once entangled, however, the dolphins cannot reverse out, and drown within a few minutes.
Having established the cause of the problem, Slooten and Dawson turned their attention to the dolphins’ reproductive rate, and found that it was little higher than their natural mortality— the extra losses due to set-net entanglement were not being offset by increased reproduction. The researchers estimated that maximum population growth rate in the absence of human impacts was a modest 2-4 per cent. At that rate, the Banks Peninsula population could increase no more than 15-30 a year, whereas the average number killed in set-nets between 1984 and 1988 was 57 per year.
The implications were obvious, and in 1988 the Minister of Conservation took the precautionary step of declaring a 1170-square kilometre area of sea off Banks Peninsula a Marine Mammal Sanctuary. Commercial gill-netting is now banned year-round, amateur gill-netting banned during summer, and stringent restrictions are placed on how and where nets may be set.
Dolphin deaths are a problem not just in New Zealand waters. Over the past three decades as many as 12 million dolphins may have been killed in the eastern tropical Pacific tuna fishery as by-catch. Deliberate kills and pollution-related die-offs account for additional tens of thousands of dolphin deaths each year, and no one knows how many thousands of dolphins have met their end entangled in the giant “wall of death” driftnets of the Pacific.
With few accurate records of past population size, it is difficult to assess the true state of global dolphin populations. However, the main species to be found around New Zealand (Hector’s, dusky, common, bottlenose and orca) are listed among the species “significantly reduced in at least part of their range” by the Convention on International Trade in Endangered Species (CITES).
New Zealand dolphins have one of the world’s highest rates of DDT contamination from agricultural run-off into rivers and coastal areas, and this poses an ongoing risk to their reproductive health. There are also tuna and other fishing-related deaths in nets off New Zealand caused by foreign-registered “super-seiners” which fish from Great Barrier to North Cape during the summer months.
On the drive back to Christchurch in Liz Slooten’s juddery old flatbed ute, the conversation shifts from set-nets to the finer points of dolphin communication. Above the racket of the diesel engine Liz explains how she and her partner have tried to link Hector’s dolphins’ high-frequency clicks to observable behaviour patterns.
After analysing 7662 Hectors’ “sound bites,” they found that the use of complex click patterns increases as the dolphin group increases in size, suggesting a role in social interaction. A particular type of ultrasonic click was found to be associated with feeding, and “cries,” the only sound in their repertoire audible to humans, were usually made when dolphins were jumping, tail-slapping and chasing each other in active play.
Slooten and Dawson’s work with Hector’s dolphins is about as far as anyone has got with unravelling how dolphins communicate in the wild. Even so, they are wary of making grandiose claims about dolphin language.
Liz feels that our human fixation with verbal communication also needs to be reconsidered. “Animals can ‘read’ body postures and sense human intentions like aggression,” she says. “They are not dumb beasts. Dolphins may not use sound as a language in the sense that we know it, with syntax or grammar, but that does not mean they cannot communicate complex information.”
US dolphin researcher Greg Stone, who has been in Akaroa as part of a three-year research programme to assess the effect of the sanctuary on the Hector’s dolphin population, agrees. “It’s a tantalising notion that dolphins possess a culture or a consciousness, but I don’t think that is the case. They are animals with a world of their own, somewhere in there with chimps, dogs and cats. Sure, they can recognise boats, and possibly individual people, but I don’t see any telepathy-type stuff.”
Much of the overseas work on dolphin language has been conducted with bottlenose dolphins—the large “Flipper”-type dolphin with its permanently smiling mouth and friendly manner. In comparison with Hectors, research into bottlenoses is in its infancy in New Zealand. The first baseline study of a specific population is being brought to completion at the moment by one of Slooten and Dawson’s students, Jami Williams. Over the past three years she has carried out surveys of bottlenose dolphins in Fiordland’s Doubtful Sound. By photographing nicks and scars, Williams has identified 39 individuals which appear to reside in the Sound year-round. Allowing for those individuals without distinctive marks, the resident population probably numbers fewer than 70.
Large though they are, bottlenoses are not the biggest dolphin species. That honour goes to Orcinus orca, better known as the killer whale. Male orca can reach nine metres in length, and weigh up to eight tonnes. They have the widest distribution of any marine mammal, ranging from the tropics to the Arctic and Antarctic.
Jet black from the tip of the snout to the tail, with a white patch behind the eye, distinct black-and-white markings underneath and an unusually large triangular dorsal fin, the orca (meaning “devil” in Latin) is in a class of its own.
In New Zealand, the species is most commonly encountered in Cook Strait or in larger harbours such as Wellington and the Bay of Islands. At Kaikoura orca are treated like royalty, with their arrival announced on the radio.
Just a few weeks before my trip there, Brent McFadden had reported a pod of several orca passing through Kaikoura’s South Bay. What he calls a “scout group” of duskies immediately went to meet them in the open water, while the calves and main dusky herd moved close inshore for protection.
McFadden’s interpretation is that the duskies went out to size up the orca, having heard them coming. Perhaps, he conjectures, they may even have been prepared to sacrifice themselves to stave off an attack on the main group. “The duskies came up fast and, without hesitating or slowing down, wove in and out of the orca pod. The orca didn’t attempt to catch the duskies—it seemed to be a game in which they sounded each other out,” he recalls.
“The scouts returned to the main pod, and they all moved into the shallows around the rocks—closer in than I have ever seen them before.”
The orca’s fearsome reputation as a predator is legendary, probably stemming from 18th century European whalers who witnessed “killer whales” tearing the lips and tongues from great whales several times their size. The writer A. J. Villiers described just such an attack, on a blue whale, in 1925: “Two of the pugnacious killers attached themselves, one on either side, to the great mammal’s lower jaw, and appeared to be bearing down upon it with all the strength of their furiously struggling bodies, while two other of the assailants kept making short furious rushes at the great whale, and seemed to hurl themselves up and down on his exposed back, their writhing little bodies sounding on his body with great thwacks.”
The whale was killed, and the orca indeed fed on its tongue. “They had attacked the giant for nothing more than the delicacy of his tongue,” concluded the writer.
The orca’s eccentric taste for whale tongue formed the basis for a remarkable co-operative whaling venture between humans and orca in Twofold Bay, Australia, a century ago. In his book Killers of Eden Tom Mead describes how a pod of orca would herd humpback whales into the bay while a local whaling family rowed out to harpoon them. “The tongue was the only part the killers would eat, and it was their reward for the help they gave.” This curious behaviour took place from 1860 until 1930, when “Old Tom,” a large male orca, was found washed ashore dead. He had been helping the whalers for over 60 years.
Besides whales, orca are known to hunt dolphins, sharks and various types of seal. Off the coast of Patagonia orca lunge out of the surf on to a steep beach to pursue seals even on to land, manoeuvring around on their flippers before shuffling back into the water and out to sea to devyour their victim. Although potentially dangerous to humans, there are no authenticated accounts of any fatal attacks.
Of all dolphin behaviours, the most baffling—and tragic—are the strandings. New Zealand has one of the highest rates of strandings in the world, with four localities being particularly infamous traps: the Chatham Islands, Mahia Peninsula, Farewell Spit and Muriwai. Since stranding records began in 1978, there have been 146 common dolphin strandings, 142 bottlenose, 73 dusky, 59 Hector’s, 49 orca and a massive 5442 pilot whales. In all species except pilot whales, strandings have been individuals or small groups of no more than ten. For some reason, pilot whales strand en masse.
Various theories for stranding have been advanced. Autopsies on some dolphins have shown parasitic illnesses that infect and block air passages, and thus impair the animal’s acoustics. Other animals may simply become distraught after net entanglement or damage from boat propellers. It may be that ocean-going species are not used to close, inshore waters, and become disoriented by sloping sandbanks and deceptive topographic features. Some scientists believe the phases of the moon play a part, others that magnetic field anomalies are to blame, but as yet there is no clear answer, and the strandings continue.
While strandings can and do bring about great displays of public sympathy and concern, it is the notion of cetacean intelligence that produces the greatest human fascination. We observe their incredible ability to imitate and learn, consider their history of co-operation with humans, and wonder if there is some empathy deeper than instinct behind those gentle eyes.
Since experiments began in the 1950s, a variety of empirical measurements of dolphin intelligence have been put forward, such as the ratio of brain volume to body surface area (which for the bottlenose dolphin reaches 5.6, compared to the human value of around 7.4, and 2.5 for the chimpanzee), and the ratio of brain weight to spinal cord (which in humans is 50:1, in dolphins around 40:1 and in apes 8:1).
But these measurements offer little more than one-dimensional comparisons. The key area of the human brain linked to intelligence is the neocortex. In dolphins this part covers 98 per cent of the cortex—a higher figure than for humans. Does this imply cognitive ability? A consciousness in the oceans? Indeed, are dolphins our brothers and sisters under the skin?
Research with captive dolphins has revealed that they are good mimics who can copy a human voice or computer-generated sound, respond to voice commands and even repeat words spontaneously. In the US, bottlenose dolphins have been trained to perform tasks using a whistle language similar to that used to control sheep dogs. Others have understood and responded to “sentences” of 2-5 words, as well as mixed sound and gesture commands.
The dolphin’s apparent intelligence, aquadynamic design and sonar capabilities are also the kind of faculties military forces wish to procure. Recognising the dolphin’s ten million year competitive advantage over Homo sapiens in the sea, the US Navy drafted its first recruit 30 years ago, and has since trained more than 200 dolphins to perform such tasks as attaching explosives to ships, detecting mines and guarding military bases. A team of dolphins was one of the less publicised forces sent to Vietnam in 1971. Their job was to attach mines to Vietnamese targets, detach themselves and swim away.
“Dolphin is a powerful word,” says author, linguist and would-be inter-species communicator Wade Doak, doyen of New Zealand’s dolphinologists. With his wife Jan, Doak has spent much of the past 20 years exploring dolphin intelligence and communication.
Early years were spent developing an unorthodox diver’s “dolphin suit,” with fused flippers and hank. operated “fins,” and using hydrdv, phones to record and play back dolphin sounds. He recalls those days “before the Wright brothers learned to fly,” when dolphin encounters were a “hello-goodbye” affair.
“Now there is a global desire to swim with dolphins,” he remarks. “In the early days we were scared of dolphins. But as more dolphins were captured, people became less scared of them, and started to think of them as having some relationship with humans.” Despite the shift in public perception, he still thinks many people have a distorted view of dolphins While some deify and “Disneyfy” them, others regard them with “institutionalised skepticism.”
Doak is scathing about the more outlandish “New Agers” he has encountered, recalling with disdain a group of “underwater dolphin blithers” who, in the early 1980s, “stood around naked, calling and clicking stones in the surf. After that incident I got so many crank calls that I had to go ex-directory.” He knows of people in the US who believe strandings and driftnet deaths are deliberate suicidal messages from dolphins warning us of imminent environmental collapse.
Perhaps because communication and intelligence are hard to quantify or prove, Doak refuses to be pinned down, preferring to call dolphins our “closest brain neighbours.”
“I think it is an intuitive thing, not like clinical psychology where you apply some kind of IQ test. You can’t just put them in a lab and say, ‘There, that’s how intelligent they are.—
He is also uneasy about being asked to describe his most profound dolphin encounter (he calls them “interlocks”). “Perhaps it was when we set up a two-way underwater telephone communication system in the water at Whitianga with a dolphin we called Rampal. He responded to our excitement with clicks and noises, even though we were not always in the water with him. That was probably the most abstract level experience. But then there was the dolphin that pointed out a hook in another dolphin’s skin to a diver, asking for help, and another dolphin that led a diver to his lost camera.”
Doak thinks that captive dolphins involved in behavioural experiments do not take their fish rewards just out of appetite, but also out of boredom, and a need for stimulation. After all, he points out, there is not much else for a dolphin in an empty tank to do all day. He recalls experiments in which the subject dolphin began to give the wrong answers, and brought the fish to the scientists!
In another experiment that rewarded new behaviour with a fish, the dolphins came up with so many new moves that the team were unable to keep up with them. Could these animals have been making fun of our naive research?
Doak gives a wry smile: “I prefer to let people form their own impressions from intuitive feelings. Intelligence is not the kind of thing you can calculate or draw a chalk line around—there are shades of grey around the edges.”
As for me, I’m keeping an open mind. By the time we have it all worked out, the dolphins will have long since said, “Goodbye, and thanks for all the fish.”