IELTS Handbook 17 – Test 3

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Lưu ý

Những từ bôi vàng: Các keywords xuất hiện trong câu hỏi

Những từ bôi cam: Ngôn ngữ chỉ dẫn – Các đầu mục lớn

Những từ bôi xanh:Đáp án

Scientists believe that a majority of the earth’s bird population migrate in some fashion or other. Some travel seasonally for relatively short distances, such as birds that move from their winter habitats in lowlands to mountain tops for the summers. Others, like the Arctic Tern, travel more than 25,000 miles seasonally between the northern and southern poles. Bird migration has been studied over many centuries through a variety of observations.

But until relatively recently, where birds went to in the winter was considered something of a mystery. The lack of modern science and technology led to many theories that we now recognize as error-filled and even somewhat amusing. Take hibernation theory for example – two thousand years ago, it was commonly believed that when birds left an area, they went underwater to hibernate in the seas and oceans. Another theory for the regular appearance and disappearance of birds was that they spend winter hidden in mud till the weather changed and food became abundant again [chúng trải qua mùa đông ẩn mình trong bùn cho đến khi thời tiết thay đổi và thức ăn trở nên dồi dào trở lại] (Question 31). The theory that some birds hibernate persisted until experiments were done on caged birds in the 1940s which demonstrated that birds have no hibernation instinct.

One of the earliest naturalists and philosophers from ancient Greece was Aristotle who was the first writer to discuss the disappearance and reappearance of some bird species at certain times of year. He developed the theory of transmutation, the seasonal change of one species into another, by observing redstarts and robins. He observed that in the autumn, small birds called ‘redstarts’ began to lose their feathers [vào mùa thu, những con chim nhỏ được gọi là “chim đỏ đuôi” bắt đầu rụng lông] (Question 32), which convinced Aristotle that they changed into robins for the winter, and back into redstarts in the summer. These assumptions are understandable [=logical] given that this pair of species are similar in shape [Những giả thiết này có thể hiểu được vì cặp loài này có hình dáng giống nhau] (Question 33), but are a classic example of an incorrect interpretation based on correct observations.

The most bizarre theory was put forward by an English amateur scientist, Charles Morton, in the seventeenth century. He wrote a surprisingly well-regarded paper claiming that birds migrate to the moon and back every year [Ông đã viết một bài báo được đánh giá cao một cách đáng ngạc nhiên khi khẳng định rằng các loài chim di cư lên mặt trăng và quay trở lại hàng năm] (Question 34). He came to this conclusion as the only logical explanation for the total disappearance of some species.

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One of the key moments in the development of migration theory came in 1822 when a white stork was shot in Germany. This particular stork made history because of the long spear in its neck which incredibly had not killed it [Con cò đặc biệt này đã làm nên lịch sử vì chiếc giáo dài trên cổ đã không thể giết chết nó] (Question 35) – everyone immediately realised this spear was definitely not European. It turned out to be a spear from a tribe in Central Africa. This was a truly defining moment in the history of ornithology because it was the first evidence that storks spend their winters in sub-Saharan Africa [đây là bằng chứng đầu tiên cho thấy cò trải qua mùa đông ở châu Phi cận Sahara] (Question 36). You can still see the ‘arrow stork’ in the Zoological Collection of the University of Rostock in Germany.

People gradually became aware that European birds moved south in autumn and north in summer but didn’t know much about it until the practice of catching birds and putting rings on their legs became established. Before this, very little information was available about the actual destinations of particular species and how they travelled there [=journey] [Trước đó, rất ít thông tin có sẵn về các điểm đến thực tế của các loài cụ thể và cách chúng đi đến đó] (Question 37). People speculated that larger birds provided a kind of taxi service for smaller birds by carrying them on their backs. This idea came about because it seemed impossible that small birds weighing only a few grams could fly over vast [=huge] oceans [dường như những con chim nhỏ chỉ nặng vài gram không thể thể bay qua đại dương rộng lớn] (Question 38). This idea was supported by observations of bird behaviour such as the harassment of larger birds by smaller birds.

The development of bird ringing, by a Danish schoolteacher, Hans Christian Cornelius Mortensen, made many discoveries possible. This is still common practice today and relies upon [=depended on] what is known as ‘recovery’ [Đây vẫn là một cách thực hiện phổ biến ngày nay và dựa trên những gì được gọi là “sự tìm lại”] (Question 39) – this is when ringed birds are found dead in the place they have migrated to, and identified. Huge amounts of data were gathered in the early part of the twentieth century and for the first time in history people understood where birds actually went to in winter. In 1931, an atlas was published [=printed] showing where the most common species of European birds migrated to [Năm 1931, một tập bản đồ được xuất bản cho thấy nơi những loài chim phổ biến nhất ở châu Âu di cư đến] (Question 40). More recent theories about bird migration…