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 【Q31】 till the weather changed and food became abundant again. 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 【Q32】, which convinced Aristotle that they changed into robins for the winter, and back into redstarts in the summer. These assumptions are understandable given that this pair of species are similar in shape 【Q33】, 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 【Q34】. He came to this conclusion as the only logical explanation for the total disappearance of some species.
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 【Q35】 which incredibly had not killed it – 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 【Q36】. 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 【Q37】 and how they travelled there. 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 oceans 【Q38】. 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 what is known as ‘recovery’ 【Q39】 – 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 showing where the most common species of European birds migrated to 【Q40】. More recent theories about bird migration …
Complete the notes below.
Write ONE WORD ONLY for each answer.
听前预测：定位词为 Hibernation theory、underwater；提示词为 buried、in，此处应填名词，表示鸟类生活的地点或环境。
题目解析：开篇有较长时间的背景介绍，时长约 50 秒，这段介绍虽然并未涉及出题句，但要求考生紧跟题干信息（如 seasonally 原词出现）。录音中出现小标题 Hibernation theory 后，接着出现定位词 underwater，注意不要填写随后出现的名词 seas 或 oceans，首先这两个词是 underwater 的具体体现，另外它们存在并列关系， 而题目对答案词的要求是 ONE WORD ONLY，因此都排除。接着录音中提到
Another theory，表明该句跟前面存在并列或递进关系，跟题干中的 or 符合，随后听到“… they spent winter hidden in the mud …”，其中 hidden 表示“隐藏”， 对应题干中的 buried，因此 mud 符合题干要求。
听前预测：定位词为 autumn、redstarts、robins；提示词为 loss of，此处应填名词。
题目解析：本题跟上题虽然间隔时间较长（40 秒左右），但题干中很多已知信息在录音都原词出现，如 caged birds、Aristotle, transmutation 等，只要考生边听边扫读题干信息，基本不会出现定位问题。本题定位词 autumn 和 redstarts 原词出现，随 后提到“… small birds called ‘redstarts’ began to lose their feathers …”，其中 lose 对应题干中的 loss of，因此本题答案为 feathers。随后录音提到“… changed into robins …”，对应题干中的 turned into robins，再次确认 feathers 为答案。
听前预测：定位词为 assumptions、two species；提示词为 a、similar，此处应填单数可数名词。
题目解析：本题跟上题题干相连，所以考生完成上题后可以马上听到本题定位词，提示词 similar 也原词出现。随后根据题干要求捕捉名词即可，录音提到“… this pair of species are similar in shape …”，因此 shape 符合题干要求。
听前预测：定位词为 17th Century、Charles Morton；提示词为 fly to the, winter，此处应填地点类名词。
题目解析：本题定位不难，两组定位词均为特殊名词原词出现。随后考生可以听到 paper、birds、moon、year 等重读的名词，根据题干要求，其中只有 moon 为地点。
听前预测：定位词为 1822、stork、Germany、African spear；提示词为 in its，此处应填名词，表示鸟的身体部位。
题目解析：本题定位不难，题干定位词皆原词重现，随后可以依次听到 history、neck 这两个重读的名词，根据题干的要求（鸟的身体部位），neck 符合。题干另一个定位词 African 在随后出现“It turned out to be a pear from a tribe in Central Africa.”。
听前预测：定位词为 storks、Africa；提示词为 previously、no，此处应填名词。
题目解析：在录音中本题答案先于定位词出现，建议考生结合上题信息定位。上题结束后，考生可以依次听到的重读名词有 moment, history, ornithology, evidence 等，其中 ornithology 难度高，可能大部分考生不认识，但可以通过后缀 -ology 判断是一个表示学科的单词，代入题干内容上不合适。符合题干内容要求的词只有 evidence。另一种做法是找到题干在录音中的替换信息，其中“previously there had been no …”在录音中被替换成“it was the first …”；“storks migrate to Africa”在录音中对应“storks spend their winters in sub-Saharan African”。本题不仅需要理解题干，还需记住比较多的细节信息，理解雅思中的替换方式，难度较大。
听前预测：提示词为 Little、the、journeys，此处应填名词。
题目解析：跟 36 题类似，本题题干定位较难，需要结合上题信息定位。上题结束后， “People gradually became aware …”开始，考生依次可以听到的重读名词有 south、autumn、north、summer、practice、rings，至此虽然题干中一个信息 ringing 已经出现（ring），但没有可以代入题干的词，因此意识到答案词可能还未出现，需要继续听，接着听到 destinations，符合题干要求。另一种做法是找到题干在录音中的替换信息，“Little was known about …”对应录音中的“… very little information was available about …”；journeys 对应 travelled there。
听前预测：定位词为 large birds、small birds；提示词为 incapable、travel across，此处应填地点类名词。
题目解析：本题定位不难，定位词在录音中都原词重现，接着依次可以听到重读的名词有 taxi service、backs、grams、oceans，其中符合题干要求的地点类名词只有 oceans。能力较高的考生可以听出题干中的“… large birds carried smaller birds …”在录音中对应“… larger birds provide a kind of taxi service for smaller birds by carried them on their backs”；incapable 被替换成 impossible；travelling across 被 替换成 fly over；huge 被替换成 vast。
听前预测：定位词为 Ringing；提示词为 called the、dead，此处应填专有名词。
题目解析：本题定位不难，Ringing 原词重现，虽然本题从题干和录音内容理解上来讲难度较大，但题干中的 called 和引号提示我们去录音中捕捉专有名词，录音中可以 听到“… what is known as ‘recovery’ …”，其中 known as（被称作）对应 called， 因此确认 recovery 为本题答案，题干中 dead 这个信息也在随后原词出现。
听前预测：定位词为 1931、European；提示词为 first、printed，此处应填名词。
题目解析：本题定位词 1931 原词出现后，录音中立即提到“an atlas was published …”，此时要求考生立即判断出，其中 published 替换题干中的 printed，因此答案为 atlas。题干的其他信息 the migration of European birds 随后出现，对应录音中的“… European birds migrated”。本题要求学生对题干信息在录音的替换作出及时反应；同时答案词 atlas 属于高分段词汇，有一定的难度。