Reading Test 25
The Tuatara of New Zealand
Tuatara are lizard-like reptiles, found only in New Zealand. They are representative of ancient life forms. Tuatara are the only living representatives of an ancient lineage of reptiles called Sphenodontia, which is over 250 million years old. Because tuatara still look like fossils of reptiles that lived at the time of dinosaurs, they are often called living fossils. Now just two species of tuatara survive, and only in New Zealand. One of these is the Brothers Island tuatara, which has been reintroduced to sanctuaries (safe places for wildlife), only on North Brother Island. The other species is the common tuatara, which survives on many other offshore islands. Although the tuatara species appear similar, they have genetic differences. Tuatara bones have been found in many parts of New Zealand. Where dated, they are usually a few hundred to 5,000 years old. It is not known whether these bones are from the two living species or other species that are now extinct.
Many anatomical features distinguish tuatara from other living reptiles—for example, they have a unique pattern of openings in the skull and a unique type of haemoglobin in the blood, and males have no external reproductive organ. Adults are between 30 and 75 centimetres long, and weigh between 250 and 1,200 grams. Males are larger than females, and have more developed spines in the crest along the neck, back, and tail.
The male tuatara courts the female by approaching her with a proud walk. Tuatara mate in late summer, and the female usually lays 6–10 eggs the following spring, in a shallow nest at ground level. She may guard the nest for a few nights, then return to her burrow underground. The eggs incubate for about a year, so hatchlings emerge about the time that eggs are being laid in the following season. Evidence indicates the gender of tuatara hatchlings is determined by both genetic and environmental factors. It is said that it is more likely for warmer eggs to produce male tuatara, and cooler eggs to produce females. The hatchlings receive no parental care and need to find their own food.
Tuatara live for a relatively long time, reaching reproductive maturity at about 15 years, and may breed for many decades. Their maximum lifespan is not known for certain, but many individuals have exceeded 80 years still looking vigorous and healthy. Tuatara live in underground burrows and are more active at night, but will come out during the day to bask in the sun. Both males and females will defend the territory around their burrow by posturing and fighting other tuatara. Teeth are their main weapons, and a bite can cause serious injury. Tuatara are carnivores: their diet includes insects, lizards, and the baby seabirds with which they often share burrows.
Tuatara were once widespread and abundant on the New Zealand mainland, but when Polynesian settlers arrived in New Zealand, in about 1250–1300 AD, they brought with them mammals which killed tuatara. By the time of European settlement, in the 1840s, tuatara were nearly gone from the mainland. Now, some islands previously uninhabited by humans, but now free of mammals, have been reinhabited by rats and other mammalian predators.
Tuatara can live in remarkably dense populations. Most tuatara islands have 50–100 tuatara per square hectare—so an island of only 10 hectares may have thousands of tuatara. Larger islands with many seabirds and invertebrates, which tuatara eat, may have greater densities. The largest population is on Stephens Island, where there are estimated to be as many as 2,500 per hectare in some places, and a total of at least 30,000. The total number of tuatara on all the islands is estimated to be between 50,000 and 100,000.
Legal protection was granted to tuatara and the islands they occupied in 1895, but the reptiles continued to decline. Since then, active conservation management has reversed the decline, and new populations have become established on predator-free islands. In the mid-1980s the New Zealand Wildlife Service and its successor, the Department of Conservation, developed ways to eradicate rats from islands. Rats have now gone from almost all of the tuatara islands, making these safe for many threatened native species. In addition, the collection by conservationists of eggs for incubation in captivity, breeding in captivity, and moving tuatara to rat-islands off the north coast, or Stephens Island in Cook Strait, were never invaded by rats, and had few of the other mammals that threaten native animals. The tiny, 4-hectare North Brother Island, in Cook Strait, has new tuatara populations. New predator-free islands have increased the number of islands that are inhabited by tuatara to 37. Many new tuatara populations are planned for islands and mainland reserves that have been freed of predators.
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The Lost City
A
When the US explorer and academic Hiram Bingham arrived in South America in 1911, he was ready for what was to be the greatest achievement of his life: the exploration of the remote interior to the west of Cusco, the old capital of the Inca Empire in the Andes mountains of Peru. His goal was to locate the remains of a city called Vitcos, the last capital of the Inca civilisation.
Cusco lies on a high plateau at an elevation of more than 3,000 metres, and Bingham’s plan was to descend from this plateau along the valley of the Urubamba river, which takes a circuitous route down to the Amazon and passes through an area of dramatic canyons and mountain ranges.
B
When Bingham and his team set off down the Urubamba in late July, they had an advantage over travellers who had preceded them: a track had recently been blasted down the valley canyon to enable rubber to be brought up by mules from the jungle. Almost all previous travellers had left the river at Ollantaytambo and taken a high pass across the mountains to rejoin the river lower down, thereby cutting a substantial corner, but also therefore never passing through the area around Machu Picchu.
C
On 24 July they were a few days into their descent of the valley. The day began slowly, with Bingham trying to arrange sufficient mules for the next stage of the trek. His companions showed no interest in accompanying him up the nearby hill to see some ruins that a local farmer, Melchor Arteaga, had told them about the night before. The morning was dull and damp, and also seems to have been least keen on the prospect of climbing the hill. In his book Lost City of the Incas, he relates that he made the ascent without having the least expectation that he would find anything at the top.
D
Bingham writes about the approach in vivid style in his book. First, as he climbs up the hill, he describes the ever-present possibility of deadly snakes, “capable of making considerable springs when in pursuit of their prey”; not that he sees any. Then there’s a sense of mounting discovery as he comes across great sweeps of terraces, then a mausoleum, followed by monumental staircases and, finally, the grand ceremonial buildings of Machu Picchu. “It seemed like an unbelievable dream the sight held me spellbound,” he wrote.
E
We should remember, however, that Lost City of the Incas is a work of hindsight, not written until 1948, many years after his journey. What Bingham’s notes of the time reveal is a much more gradual appreciation of his achievement. He spent the afternoon of the ruins noting down the dimensions of some of the buildings, then descending to rejoin his companions. In doing so, he seems to have side-stepped his discovery. At this stage, he didn’t realise the extent or the importance of the site, nor did he realise what he had made out of the discovery.
F
However, soon after returning it occurred to him that he could make a name for himself from this discovery. When he came to write the National Geographic magazine article that would make the story to the world in April 1913, he knew he had found a truly remarkable site.
He wondered whether it could also have been the birthplace of the very first Inca, Manco the Great, and whether it could also have been what chroniclers described as the “last city of the Incas.” In his terms it referred to Vilcabamba, the settlement where the Incas had fled from Spanish invaders in the 1530s. Bingham made desperate attempts to prove this belief for nearly 40 years. Sadly, his vision of the site as both the beginning and end of the Inca civilisation, while a magnificent one, is inaccurate. We now know that Vilcabamba actually lies 65 kilometres away in the depths of the jungle.
G
One question that has perplexed visitors, historians, and archaeologists alike ever since Bingham is why the site seems to have been abandoned before the Spanish Conquest. There are no references to it by any of the Spanish chroniclers — and if they had known of its existence so close to Cusco they would certainly have come in search of gold.
One idea that has gained wide acceptance over the past few years is that it was a country estate built by an Inca emperor to escape the cold winters of Cusco, where the elite could supervise monumental architecture and religious events. Furthermore, the particular style of architecture of Machu Picchu suggests that it was constructed at the time of the greatest of all the Incas, the emperor Pachacuti (1438–71). By custom, Pachacuti’s descendants built other similar estates for their own use, and so Machu Picchu would have been abandoned after his death, some 50 years before the Spanish Conquest.
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The Cane Toad in Australia
Paragraph A
The cane toad was introduced into Australia in 1935 to control sugar cane pests in Queensland. One hundred and one cane toads arrived at Edmonton in June 1935. Breeding occurred almost immediately. The cane toad is tough and adaptable, as well as being poisonous throughout its life cycle, and has few predators in Australia.
Paragraph B
Cane toads are large, heavily built amphibians with dry, warty skin. They have a bony head and over their eyes are bony ridges that meet above the nose. They sit upright and move in short rapid hops. Their hind feet have leathery webbing between the toes and their front feet are unwebbed. Adult cane toads have large swellings called parotoid glands—one on each shoulder behind the eardrum. Cane toads may be grey, yellowish, olive-brown or reddish-brown, and their bellies are pale with dark mottling. Average-sized adults are ten to fifteen centimetres long. The largest female measured in Queensland was twenty-four centimetres long and weighed over three kilograms. Male cane toads are smaller and warty around their females. During the breeding season males develop dark lumps (nuptial pads) on their outer two fingers; these help them cling to a female while mating. Their mating call is a long loud purring trill. Cane toad spawn is exclusive in Australia. It is laid in long strings of transparent jelly enclosing double rows of black eggs. The spawn lies in dense dark masses around water plants, and hangs in ropy strands if picked up.
Paragraph C
The natural range of cane toads extends from the southern United States to tropical South America. In 2002, cane toads occurred throughout the eastern and northern half of Queensland and have extended their range to the river catchments surrounding Kakadu National Park in the Northern Territory. In New South Wales, they occur as far south as Yamba and Port Macquarie.
Paragraph D
Cane toads tolerate a broad range of environmental and climatic conditions and appear to be able to survive and adapt to almost any environment system, including sea water for short periods of time. This to a large extent explains their success in their spreading in Australia. Cane toads are found in environments ranging from sand dunes and coastal heath to the margins of rainforest and mangroves. They are most abundant in open clearings in urban areas, and in grassland and woodland.
Paragraph E
Cane toads eat almost anything they can swallow, including pet food, carrion and household scraps, as well as the diet of most frogs: living insects. Beetles, honey bees, ants, winged termites, cockroaches and moths are eaten in abundance. Marine snails, smaller toads and native frogs, small snakes, and small mammals are occasionally eaten by cane toads. The tadpoles of cane toads eat algae and other aquatic organisms which they rasp off with rows of tiny peg-like teeth. They also filter organic matter from the water. Large tadpoles sometimes eat cane toad eggs.
Paragraph F
Cane toads were introduced to Australia to eat the French’s Cane Beetle and the Greyback Cane Beetle. The white grub larvae of these beetles eat the roots of sugar cane and kill or stunt the plants. The Australian Bureau of Sugar Experimental Stations imported about a hundred toads from Hawaii to the Meringa Experimental Station near Cairns. The toads bred quickly and more than three thousand were released in the sugar cane plantations of north Queensland in July 1935. At that time, many farmers and scientists warned of the dangers of liberating cane toads in Australia. Their protests resulted in a brief moratorium on the release of toads, but releases resumed in 1936. The protestors were right. Firstly, cane toads compete for the resources of native animals, like food, which affects native populations. Secondly, cane toads don’t have as many established predators as native animals and so their population grows quickly. Finally, some native animals who would normally feed on frogs try to eat toads and get poisoned.
Paragraph G
All stages of the cane toad’s life cycle are poisonous. No humans have died in Australia from cane toad poison, but overseas people have died after eating toads and even soup made from boiled toad eggs. Cane toads are also poisonous to pets. In Hawaii, up to fifty dogs a year have died after having cane toads in their mouths. Signs of dogs being poisoned through ingestion include profuse salivation, twitching, vomiting, shallow breathing, and collapse of the hind limbs. Death may occur by cardiac arrest within fifteen minutes. A cane toad responds to threat by turning side-on so its parotoid glands are directed towards the attacker. The toad usually oozes out drops of thick, milky poison, but can also squirt a fine spray for a short distance if very angry. The poison is absorbed through mucous membranes such as eyes, mouth, and nose, and in humans may cause intense pain, temporary blindness and inflammation.
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