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Questions 7-13
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Write your answers in boxes 7-13 on your answer sheet.
原文
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 tuatara have reached 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 sexes are territorial，and males aggressively defend their territory by posing and fighting if necessary. Teeth are their main weapons， and a bite can cause serious injury. Tuatara are carnivorous， eating invertebrates， 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 Pacific rats which killed tuatara. By the time of European settlement，in the 1840s，tuatara were almost extinct on the New Zealand mainland. Some islands provided temporary havens，but soon these too began to be invaded by rats and other mammalian predators.
Gradually tuatara became restricted to 32 nearshore islands. Many of these islands were tiny，some as small as only one hectare . A few， such as the Poor Knights Islands off the Northland coast，or Stephens Island in Cook Strait，were never invaded by rats，and had few of the other mammals that threaten native animals. The common tuatara lives on islands off the north- eastern coast of New Zealand，and on some islands in Cook Strait. The Brothers Island tuatara survived only on the tiny，4-hectare North Brother Island，in Cook Strait. However，two new populations of the Brothers Island tuatara have been created on Titi Island in the Marlborough Sounds，and on Somes Island in Wellington Harbour.
Tuatara can live in remarkably dense populations. Most tuatara islands have 50-100 tuatar per square hectare - so an island of only 10 hectares may have a population of hundreds. 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 a 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.