To South Americans, robins are birds that fly north every spring. To North Americans, the robins simply vacation in the south each winter. Furthermore, they fly to very specific places in South America and will often come back to the same trees in North American yards the following spring. The question is not why they would leave the cold of winter so much as how they find their way around. The question perplexed people for years, until, in the 1950s, a German scientist named Gustave Kramer provided some answers and, in the process, raised new questions.
Kramer initiated important new kinds of research regarding how animals orient and navigate. Orientation is simply facing in the right direction; navigation involves finding ones way from point A to point B.
Early in his research, Kramer found that caged migratory birds became very restless at about the time they would normally have begun migration in the wild. Furthermore, he noticed that as they fluttered around in the cage, they often launched themselves in the direction of their normal migratory route. He then set up experiments with caged starlings and found that their orientation was, in fact, in the proper migratory direction except when the sky was overcast, at which times there was no clear direction to their restless movements. Kramer surmised, therefore, that they were orienting according to the position of the Sun. To test this idea, he blocked their view of the Sun and used mirrors to change its apparent position. He found that under these circumstances, the birds oriented with respect to the new "Sun." They seemed to be using the Sun as a compass to determine direction. At the time, this idea seemed preposterous. How could a bird navigate by the Sun when some of us lose our way with road maps? Obviously, more testing was in order.
So, in another set of experiments, Kramer put identical food boxes around the cage, with food in only one of the boxes. The boxes were stationary, and the one containing food was always at the same point of the compass. However, its position with respect to the surroundings could be changed by revolving either the inner cage containing the birds or the outer walls, which served as the background. As long as the birds could see the Sun, no matter how their surroundings were altered, they went directly to the correct food box. Whether the box appeared in front of the right wall or the left wall, they showed no signs of confusion. On overcast days, however, the birds were disoriented and had trouble locating their food box.
In experimenting with artificial suns, Kramer made another interesting discovery. If the artificial Sun remained stationary, the birds would shift their direction with respect to it at a rate of about 15 degrees per hour, the Sun's rate of movement across the sky. Apparently, the birds were assuming that the "Sun" they saw was moving at that rate. When the real Sun was visible, however, the birds maintained a constant direction as it moved across the sky. In other words, they were able to compensate for the Sun's movement. This meant that some sort of biological clock was operating-and a very precise clock at that.
What about birds that migrate at night? Perhaps they navigate by the night sky. To test the idea, caged night-migrating birds were placed on the floor of a planetarium during their migratory period. A planetarium is essentially a theater with a domelike ceiling onto which a night sky can be projected for any night of the year. When the planetarium sky matched the sky outside, the birds fluttered in the direction of their normal migration. But when the dome was rotated, the birds changed their direction to match the artificial sky. The results clearly indicated that the birds were orienting according to the stars.
There is accumulating evidence indicating that birds navigate by using a wide variety of environmental cues. Other areas under investigation include magnetism, landmarks, coastlines, sonar, and even smells. The studies are complicated by the fact that the data are sometimes contradictory and the mechanisms apparently change from time to time. Furthermore, one sensory ability may back up another.
Paragraph 1: To South Americans, robins are birds that fly north every spring. To North Americans, the robins simply vacation in the south each winter. Furthermore, they fly to very specific places in South America and will often come back to the same trees in North American yards the following spring. The question is not why they would leave the cold of winter so much as how they find their way around. The question perplexed people for years, until, in the 1950s, a German scientist named Gustave Kramer provided some answers and, in the process, raised new questions.
1. Which of the following can be inferred about bird migration from paragraph 1?
○ Birds will take the most direct migratory route to their new habitat.
○ The purpose of migration is to join with larger groups of birds.
○ Bird migration generally involves moving back and forth between north and south.
○ The destination of birds' migration can change from year to year.
2. The word “perplexed” in the passage is closest in meaning to
○ defeated
○ interested
○ puzzled
○ occupied
Paragraph 3: Early in his research, Kramer found that caged migratory birds became very restless at about the time they would normally have begun migration in the wild. Furthermore, he noticed that as they fluttered around in the cage, they often launched themselves in the direction of their normal migratory route. He then set up experiments with caged starlings and found that their orientation was, in fact, in the proper migratory direction except when the sky was overcast, at which times there was no clear direction to their restless movements. Kramer surmised, therefore, that they were orienting according to the position of the Sun. To test this idea, he blocked their view of the Sun and used mirrors to change its apparent position. He found that under these circumstances, the birds oriented with respect to the new "Sun." They seemed to be using the Sun as a compass to determine direction. At the time, this idea seemed preposterous. How could a bird navigate by the Sun when some of us lose our way with road maps? Obviously, more testing was in order.
3. Which of the sentences below best expresses the essential information in the highlighted sentencein the passage? Incorrect choices change the meaning in important ways or leave out essential information.
○ Experiments revealed that caged starlings displayed a lack of directional sense and restlessmovements.
○ Experiments revealed that caged starlings were unable to orient themselves in the direction of their normal migratory route.
○ Experiments revealed that the restless movement of caged starlings had no clear direction.
○ Experiments revealed that caged starlings' orientation was accurate unless the weather was overcast.
4. The word “preposterous” in the passage is closest in meaning to
○ unbelievable
○ inadequate
○ limited
○ creative
5. According to paragraph 3, why did Kramer use mirrors to change the apparent position of the Sun?
○ To test the effect of light on the birds' restlessness
○ To test whether birds were using the Sun to navigate
○ To simulate the shifting of light the birds would encounter along their regular migratory route
○ To cause the birds to migrate at a different time than they would in the wild
6. According to paragraph 3, when do caged starlings become restless?
○ When the weather is overcast
○ When they are unable to identify their normal migratory route
○ When their normal time for migration arrives
○ When mirrors are used to change the apparent position of the Sun
Paragraph 4: So, in another set of experiments, Kramer put identical food boxes around the cage, with food in only one of the boxes. The boxes were stationary, and the one containing food was always at the same point of the compass. However, its position with respect to the surroundings could be changed by revolving either the inner cage containing the birds or the outer walls, which served as the background. As long as the birds could see the Sun, no matter how their surroundings were altered, they went directly to the correct food box. Whether the box appeared in front of the right wall or the left wall, they showed no signs of confusion. On overcast days, however, the birds were disoriented and had trouble locating their food box.
7. Which of the following can be inferred from paragraph 4 about Kramer s reason for filling one food box and leaving the rest empty?
○ He believed the birds would eat food from only one box.
○ He wanted to see whether the Sun alone controlled the birds' ability to navigate toward the box with food.
○ He thought that if all the boxes contained food, this would distract the birds from following their migratory route.
○ He needed to test whether the birds preferred having the food at any particular point of the compass.
Paragraph 5: In experimenting with artificial suns, Kramer made another interesting discovery. If the artificial Sun remained stationary, the birds would shift their direction with respect to it at a rate of about 15 degrees per hour, the Sun's rate of movement across the sky. Apparently, the birds were assuming that the "Sun" they saw was moving at that rate. When the real Sun was visible, however, the birds maintained a constant direction as it moved across the sky. In other words, they were able to compensate for the Sun's movement. This meant that some sort of biological clock was operating-and a very precise clock at that.
8. According to paragraph 5, how did the birds fly when the real Sun was visible?
○ They kept the direction of their flight constant.
○ They changed the direction of their flight at a rate of 15 degrees per hour.
○ They kept flying toward the Sun.
○ They flew in the same direction as the birds that were seeing the artificial Sun.
9. The experiment described in paragraph 5 caused Kramer to conclude that birds possess a biological clock because
○ when birds navigate they are able to compensate for the changing position of the Sun in the sky
○ birds innate bearings keep them oriented in a direction that is within 15 degrees of the Suns direction
○ birds' migration is triggered by natural environmental cues, such as the position of the Sun
○ birds shift their direction at a rate of 15 degrees per hour whether the Sun is visible or not
Paragraph 6: What about birds that migrate at night? Perhaps they navigate by the night sky. To test the idea, caged night-migrating birds were placed on the floor of a planetarium during their migratory period. A planetarium is essentially a theater with a domelike ceiling onto which a night sky can be projected for any night of the year. When the planetarium sky matched the sky outside, the birds fluttered in the direction of their normal migration. But when the dome was rotated, the birds changed their direction to match the artificial sky. The results clearly indicated that the birds were orienting according to the stars.
10. According to paragraph 6, how did the birds navigate in the planetarium's nighttime environment?
○ By waiting for the dome to stop rotating
○ By their position on the planetarium floor
○ By orienting themselves to the stars in the artificial night sky
○ By navigating randomly until they found the correct orientation
11. Which of the following best describes the author's presentation of information in the passage?
○ A number of experiments are described to support the idea that birds use the Sun and the night sky to navigate.
○ The author uses logic to show that the biological clock in birds is inaccurate.
○ A structured argument about the importance of internal versus external cues for navigation is presented.
○ The opposing points of view about bird migration are clarified through the study of contrasting experiments.
Paragraph 7: There is accumulating evidence indicating that birds navigate by using a wide variety of environmental cues. Other areas under investigation include magnetism, landmarks, coastlines, sonar, and even smells. The studies are complicated by the fact that the data are sometimes contradictory and the mechanisms apparently change from time to time. Furthermore, one sensory ability may back up another.
12. The word “accumulating” in the passage is closest in meaning to
○ new
○ increasing
○ convincing
○ extensive
Paragraph 4: So, in another set of experiments, Kramer put identical food boxes around the cage, with food in only one of the boxes. ■The boxes were stationary, and the one containing food was always at the same point of the compass. ■However, its position with respect to the surroundings could be changed by revolving either the inner cage containing the birds or the outer walls, which served as the background. ■As long as the birds could see the Sun, no matter how their surroundings were altered, they went directly to the correct food box. ■Whether the box appeared in front of the right wall or the left wall, they showed no signs of confusion. On overcast days, however, the birds were disoriented and had trouble locating their food box.
13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
He arranged the feed boxes at various positions on a compass.
Where would the sentence best fit?
14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Gustave Kramer conducted important research related to the ability of birds to orient and navigate.
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●
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Answer Choices
○ Because caged birds become disoriented when the sky is overcast, Kramer hypothesized that birds orient themselves according to the Sun's position.
○ In one set of experiments, Kramer placed the box containing food at the same point of the compass each time he put food boxes in the birds’ environment.
○ Kramer demonstrated that an internal biological clock allows starlings to compensate for the Sun's movement.
○ After several studies, Kramer surmised that an internal biological clock allows some species of birds to navigate at night.
○ The role of environmental cues in birds' navigation is clear, for on overcast days, birds use objects besides the Sun to orient themselves.
○ Kramer showed that night-migrating birds use the sky to navigate by the stars.
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14. Because caged birds…
Kramer demonstrated that…
Kramer showed that...
在南美，知更鳥每一年都會(huì)飛往春天時(shí)的北方。對(duì)于北美而言，知更鳥每年冬天又都會(huì)在南美度過簡(jiǎn)單的“假期”。甚至，它們會(huì)飛往南美幾個(gè)特定的地方，然后在第二年春年又飛回到北美相同的樹界范圍內(nèi)。問題是它們?yōu)槭裁磿?huì)在寒冷的冬天離開，然后又是怎樣找到遷徙的路徑的。這個(gè)問題困擾了人們很久，直到1950年代，一位名叫Gustave Kramer 的德國(guó)科學(xué)家給出了一些回答，意想不到地又提出新的問題。
就動(dòng)物如何定位和航行的問題，Kramer發(fā)起了意義重大的新類型的研究。定位僅僅就是朝向正確的方向，而航行還涉及尋找從點(diǎn)A到點(diǎn)B的路徑。
在研究早期，Kramer發(fā)現(xiàn)被關(guān)在籠子里的侯鳥同往常去野外開始遷徙的時(shí)候變得焦躁不安。而且，他注意到，當(dāng)這些鳥在籠子里躁動(dòng)不安時(shí)，它們通常會(huì)飛向遷徙路徑的方向。于是，Kramer用星椋鳥做實(shí)驗(yàn)，將它們關(guān)在籠子里，總結(jié)出了它們的遷徙方向。事實(shí)上，它們基本都能朝向正確的遷徙方向，陰天除外。因?yàn)殛幪斓臅r(shí)候它們的騷動(dòng)不安使得它們難以清楚分辨方向。因此，Kramer推測(cè)，星椋鳥是通過太陽方位來確定方向的。為了證實(shí)這一推測(cè)，他將這些鳥的眼睛蒙住，并且用鏡子改變太陽的自然方位。他發(fā)現(xiàn)，在這種環(huán)境下，這些鳥會(huì)依照新的“太陽”來定位。似乎它們把太陽作為一個(gè)羅盤來決定它們的方向。當(dāng)時(shí)人們認(rèn)為這種觀點(diǎn)非�；闹嚳尚Γ行┤嗽谟械貓D的情況下都有可能迷路，鳥兒又怎么能夠用太陽進(jìn)行導(dǎo)航呢？很顯然，接下來還需要做更多的實(shí)驗(yàn)。
因此，Kramer又做了外一組試驗(yàn)，他在鳥籠周圍擺放上相同的鳥食罐，但是只有一個(gè)食罐中有食物。所有食罐的位置都是固定的，而且裝有食物的那個(gè)食罐始終置于羅盤的同一個(gè)方位。但是，這個(gè)位置會(huì)隨周圍環(huán)境而發(fā)生變化，轉(zhuǎn)動(dòng)關(guān)著鳥的籠子或者背景墻都會(huì)使得這個(gè)食罐的位置相對(duì)改變�？墒�，只要這些鳥能夠看見太陽，不管周圍環(huán)境如何變化，它們都能立即找到那個(gè)裝有食物的食罐。不論這些食罐是在右側(cè)還是左側(cè)墻壁前方，它們都沒有表現(xiàn)出一絲疑惑。可是陰天的時(shí)候，它們就無法定位方向，很難找到裝有食物的食罐。
在關(guān)于人工太陽的試驗(yàn)中，Kramer還有一些很有意思的發(fā)現(xiàn)。如果人工的太陽位置保持不變，這些星椋鳥會(huì)以每小時(shí)15°角的速度改變它們的方向，而這一速度正好是太陽在天空中運(yùn)行的速度。顯然，這些鳥認(rèn)為它們看見的“太陽”是按照這個(gè)速度移動(dòng)的。但是，當(dāng)它們看見真正的太陽時(shí)，卻保持了恒定的方向，正如太陽在天空中移動(dòng)一樣。也就是說，它們可以適應(yīng)太陽的運(yùn)行。這就意味著，它們形成了非常精準(zhǔn)的生物鐘。
那些在夜間遷徙的侯鳥又是怎樣的呢？也許它們通過觀察夜晚的天空來定向飛行。為了證實(shí)這一推測(cè)，把在夜間遷徙的侯鳥關(guān)進(jìn)籠子里，并在它們的遷徙的時(shí)間段，將籠子置于一個(gè)天文館的地板上。這個(gè)天文館實(shí)際上是一個(gè)劇場(chǎng)，天花板呈穹頂狀可以投射出一年四季所有夜晚的景象。當(dāng)天文館的穹頂與外面的天空相吻合時(shí)，這些鳥就會(huì)朝著往常遷徙的方向拍打著翅膀。但是當(dāng)穹頂旋轉(zhuǎn)時(shí)，這些鳥就會(huì)改變方向以適應(yīng)這個(gè)人造天空。這就清楚地表明這些夜間遷徙的侯鳥是通過星宿位置來定位方向。
這些不斷積累的證據(jù)表明鳥是通過廣泛多樣的外界環(huán)境信息來引導(dǎo)它們遷徙的。而包括磁場(chǎng)、地標(biāo)、海岸線、聲波甚至氣味也被作為實(shí)驗(yàn)對(duì)象進(jìn)行觀察。由于這些數(shù)據(jù)有時(shí)會(huì)自相矛盾并且物理過程經(jīng)常隨著時(shí)間發(fā)生變化，使得這些研究非常的復(fù)雜。此外，一種感知能力可能會(huì)支持另一種。
星椋（liang）鳥，羽毛藍(lán)色，有光澤，帶乳白色斑點(diǎn)，嘴小帶黃色，眼靠近嘴根，性好溫暖，常群居，吃植物的果實(shí)或種子．
