IELTS READING TEST 31

The dingo debate

Graziers see them as pests, and poisoning is common, but some biologists think Australia’s dingoes are the best weapon in a war against imported cats and foxes.

A A plane flies a slow pattern over Carlton Hill station, a 3,600 square kilometre ranch in the Kimberley region in northwest Australia. As the plane circles, those aboard drop 1,000 small pieces of meat, one by one, onto the scrubland below, each piece laced with poison; this practice is known as baiting.

Besides 50,000 head of cattle, Carlton Hill is home to the dingo, Australia’s largest mammalian predator and the bane of a grazier’s (cattle farmer’s) life. Stuart McKechnie, manager of Carlton Hill, complains that graziers’ livelihoods are threatened when dingoes prey on cattle. But one man wants the baiting to end, and for dingoes to once again roam Australia’s wide-open spaces. According to Chris Johnson of James Cook University, ‘Australia needs more dingoes to protect our biodiversity.’

B About 4,000 years ago, Asian sailors introduced dingoes to Australia. Throughout the ensuing millennia, these descendants of the wolf spread across the continent and, as the Tasmanian tiger disappeared completely from Australia, dingoes became Australia’s top predators. As agricultural development took place, the European settlers found that they could not safely keep their livestock where dingoes roamed. So began one of the most sustained efforts at pest control in Australia’s history. Over the last 150 years, dingoes have been shot and poisoned, and fences have been used in an attempt to keep them away from livestock. But at the same time, as the European settlers tried to eliminate one native pest from Australia, they introduced more of their own.

C In 1860, the rabbit was unleashed on Australia by a wealthy landowner and by 1980 rabbits had covered most of the mainland. Rabbits provide huge prey base for two other introduced species: the feral (wild) cat and the red fox.

The interaction between foxes, cats and rabbits is a huge problem for native mammals. In good years, rabbit numbers increase dramatically, and fox and cat populations grow quickly in response to the abundance of this prey. When bad seasons follow, rabbit numbers are significantly reduced – and the dwindling but still large fox and cat populations are left with little to eat besides native mammals.

D Australian mammals generally reproduce much more slowly than rabbits, cats and foxes – an adaptation to prevent overpopulation in the arid environment, where food can be scarce and unreliable – and populations decline because they can’t grow fast enough to replace animals killed by the predators. Johnson says dingoes are the solution to this problem because they keep cat and fox populations under control. Besides regularly eating the smaller predators, dingoes will kill them simply to lessen competition.

Dingo packs live in large, stable territories and generally have only one fertile female, which limits their rate of increase. In the 4,000 years that dingoes have been in Australia, they have contributed to few, if any, extinctions, Johnson says.

E Reaching out from a desolate spot where three states meet, for 2,500 km in either direction, is the world’s longest fence, two metres high and stretching from the coast in Queensland to the Great Australian Bight in South Australia; it is there to keep dingoes out of the southeast. The fence separates the main types of livestock found in Australia. To the northwest of the fence, cattle predominate; to the southwest, sheep fill the landscape. In fact, Australia is a land dominated by these animals – 25 million cattle, 100 million sheep and just over 20 million people.

F While there is no argument that dingoes will prey on sheep if given the chance, they don’t hunt cattle once the calves are much past two or three weeks old, according to McKechnie. And a study in Queensland suggests that dingoes don’t even prey heavily on the newborn calves unless their staple prey disappears due to deteriorating conditions like drought.

This study, co-authored by Lee Allen of the Robert Wicks Research Centre in Queensland, suggests that the aggressive baiting programs used against dingoes may actually be counter-productive for graziers. When dingoes are removed from an area by baiting, the area is recolonized by younger, more solitary dingoes. These animals aren’t capable of going after the large prey like kangaroos, so they turn to calves. In their study, some of the highest rates of calf predation occurred in areas that had been baited.

G Mark Clifford, general manager of a firm that manages over 200,000 head of cattle, is not convinced by Allen’s assertion. Clifford says, ‘It’s obvious if we drop or loosen control on dingoes, we are going to lose more calves.’ He doesn’t believe that dingoes will go after kangaroos when calves are around. Nor is he persuaded of dingoes’ supposed ecological benefits, saying he is not convinced that they manage to catch cats that often, believing they are more likely to catch small native animals instead.

H McKechnie agrees that dingoes kill the wallabies (small native animals that compete with his cattle for food), but points out that in parts of Western Australia, there are no foxes, and not very many cats. He doesn’t see how relaxing controls on dingoes in his area will improve the ecological balance.

Johnson sees a need for a change in philosophy on the part of graziers. ‘There might be a number of different ways of thinking through dingo management in cattle country,’ he says. ‘At the moment, though, that hasn’t got through to graziers. There’s still just one prescription, and that is to bait as widely as possible.’

Pacific navigation and voyaging

How people migrated to the Pacific islands

The many tiny islands of the Pacific Ocean had no human population until ancestors of today’s islanders sailed from Southeast Asia in ocean-going canoes approximately 2,000 years ago. At the present time, the debate continues about exactly how they migrated such vast distances across the ocean, without any of the modern technologies we take for granted.

Although the romantic vision of some early twentieth-century writers of fleets of heroic navigators simultaneously setting sail had come to be considered by later investigators to be exaggerated, no considered assessment of Pacific voyaging was forthcoming until 1956 when the American historian Andrew Sharp published his research. Sharp challenged the ‘heroic vision’ by asserting that the expertise of the navigators was limited, and that the settlement of the islands was not systematic, being more dependent on good fortune by drifting canoes. Sharp’s theory was widely challenged, and deservedly so. If nothing else, however, it did spark renewed interest in the topic and precipitated valuable new research.

Since the 1960s a wealth of investigations has been conducted, and most of them, thankfully, have been of the ‘non-armchair’ variety. While it would be wrong to denigrate all ‘armchair’ research – that based on an examination of available published materials – it has turned out that so little progress had been made in the area of Pacific voyaging because most writers relied on the same old sources – travelers’ journals or missionary narratives compiled by unskilled observers. After Sharp, this began to change, and researchers conducted most of their investigations not in libraries, but in the field.

In 1965, David Lewis, a physician and experienced yachtsman, set to work using his own unique philosophy: he took the yacht he had owned for many years and navigated through the islands in order to contact those men who still find their way at sea using traditional methods. He then accompanied these men, in their traditional canoes, on test voyages from which all modern instruments were banished from sight, though Lewis secretly used them to confirm the navigator’s calculations. His most famous such voyage was a return trip of around 1,000 nautical miles between two islands in mid-ocean. Far from drifting, as proposed by Sharp, Lewis found that ancient navigators would have known which course to steer by memorizing which stars rose and set in certain positions along the horizon and this gave them fixed directions by which to steer their boats.

The geographer Edwin Doran followed a quite different approach. He was interested in obtaining exact data on canoe sailing performance, and to that end employed the latest electronic instrumentation. Doran traveled on board traditional sailing canoes in some of the most remote parts of the Pacific, all the while using his instruments to record canoe speeds in different wind strengths – from gales to calms – the angle canoes could sail relative to the wind. In the process, he provided the first really precise attributes of traditional sailing canoes.

A further contribution was made by Steven Horvath. As a physiologist, Horvath’s interest was not in navigation techniques or in canoes, but in the physical capabilities of the men themselves. By adapting standard physiological techniques, Horvath was able to calculate the energy expenditure required to paddle canoes of this sort at times when there was no wind to fill the sails, or when the wind was contrary. He concluded that paddles, or perhaps long oars, could indeed have propelled for long distances what were primarily sailing vessels.

Finally, a team led by P Wall Garrard conducted important research, in this case by making investigations while remaining safely in the laboratory. Wall Garrard’s unusual method was to use the findings of linguists who had studied the languages of the Pacific islands, many of which are remarkably similar although the islands where they are spoken are sometimes thousands of kilometres apart. Clever adaptation of computer simulation techniques pioneered in other disciplines allowed him to produce convincing models suggesting the migrations were indeed systematic, but not simultaneous. Wall Garrard proposed the migrations should be seen not as a single journey made by a massed fleet of canoes, but as a series of ever more ambitious voyages, each pushing further into the unknown ocean.

What do we learn about Pacific navigation and voyaging from this research? Quite correctly, none of the researchers tried to use their findings to prove one theory or another; experiments such as these cannot categorically confirm or negate a hypothesis. The strength of this research lay in the range of methodologies employed. When we splice together these findings we can propose that traditional navigators used a variety of canoe types, sources of water and navigation techniques, and it was this adaptability which was their greatest accomplishment. These navigators observed the conditions prevailing at sea at the time a voyage was made and altered their techniques accordingly. Furthermore, the canoes of the navigators were not drifting helplessly at sea but were most likely part of a systematic migration; as such, the Pacific peoples were able to view the ocean as an avenue, not a barrier, to communication before any other race on Earth.

Finally, one unexpected but most welcome consequence of this research has been a renaissance in the practice of traditional voyaging. In some groups of islands in the Pacific today young people are resurrecting the skills of their ancestors, when a few decades ago it seemed they would be lost forever.