The Long-distance Navigators - IELTS Reading Answers & Explanations
From Collins Practice Tests For IELTS 3 Academic Reading Test 2 · Part 3 · Questions 27–40
Reading Passage
You should spend about 20 minutes on Questions 27-40, which are based on Reading Passage 3 below
The long-distance navigators
A Every year between late July and October, the Arctic tern leaves its breeding grounds in the Arctic and flies over 19,000 kilometres to the Antarctic. The bird therefore sees two summers a year, once in the northern hemisphere and then again in the southern hemisphere. The Arctic tern is by no means the only bird to undertake long journeys. It is estimated that one in five bird species migrates, a feat that requires great endurance, stamina and strength. The migration patterns of birds are not random. They are very precise and follow flight routes called flyways, which connect a bird's breeding grounds with its wintering grounds, and they include stopovers for food and rest. The Americas Flyway, for example, is the route that birds take from their North American breeding grounds to wintering places in the Caribbean and South America, and the African-Eurasian Flyway connects breeding grounds in Europe and northern Asia with wintering grounds in Africa. Migration is largely driven by the weather and the availability of food. Birds in the southern hemisphere fly north, and birds in the northern hemisphere go south, seeking food and places to mate and rear their young.
B Birds have a variety of methods by which they are able to find their way across these flyways year in, year out. It seems that birds employ different geopositioning strategies according to the conditions encountered during migration. They seem able to use the position of the sun and stars, the Earth's magnetic field, smells and even landmarks to find their way, depending on which is available to them during the journey.
C When the chicks of migrating birds are born, they imprint, or intuitively learn, the map of the sky and stars as they grow in order to orientate themselves. In one famous experiment, Stephen Emlen placed Indigo buntings in a planetarium, where patterns of stars and planets are projected onto the ceiling. When the stars were projected in different positions, the birds changed position according to the new sky map, thus showing their awareness of the position of the stars.
D Obviously, birds cannot use a sky map when the weather is overcast so they must have other means to guide them on their journey. One possibility is that they use the Earth's magnetic field. How they do this is a mystery because the field is so weak. However, experiments have pointed to evidence that birds use the magnetic field in two ways. Researchers have discovered receptors, or chemicals, in their retinas and it is thought that these enable birds to sense the direction of the magnetic north. When these chemicals are exposed to light, they generate electrons that are sensitive to magnetism. If this is the case, north and south could look different to migratory birds, in effect allowing them to 'see' the magnetic field. Other researchers suggest that that birds can also sense magnetism using a molecule called magnetite. Magnetite contains iron and orientates to the north like the needle on a compass. Scientists have found magnetite on the beak of some birds and nerves that carry information about the magnetic field to their brain so that the birds can in effect 'feel' the magnetism. It seems that birds are able to sense the strength of the magnetic field, which is stronger at the poles and weaker at the equator. Traces of magnetite have also been found in humans but our ability to sense magnetic currents is far less developed than in other animals.
E There is also some evidence that birds use their sense of smell to find their way across long distances. Researchers in the UK, Spain and Italy experimented on seabirds by temporarily blocking their sense of smell using chemicals and then tracking their paths home. The birds could find their way normally when they approached land where aromas and odours are present but were less efficient at finding their direction over the sea, suggesting that smell is very important for them in piloting their routes.
F Visual clues have long been thought to be a navigational tool for birds. 'Previewing' experiments, where birds were allowed or denied visual access to a familiar site before releasing them, indicated that they use a 'familiar area map'. It seems that birds may build up a visual memory of landmarks that allows them to successfully navigate around places they have already visited. Birds that migrate in daylight often follow natural features like mountains, rivers and lakes. It has even been suggested that they follow man-made features such as roads.
Questions
Questions 27–31 Matching Headings
Reading Passage 3 has six sections, A-F.
Choose the correct heading for each section from the list of headings below.
Write the correct number, i-ix.
i. Bird migration and their routes
ii. Memorising the sky for migration purposes
iii. Using the Earth's magnetic field to navigate
iv. Humans sense Earth's magnetism like birds
v. Studies show that birds get lost over the ocean
vi. Evidence shows birds use scents to guide them
vii. Ways used to navigate migration routes
viii. Familiar places guide birds across the land
ix. The navigation strategy most used by birds
Questions 32–40 Note Completion
Complete the notes below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Research and experiments
Imprinting: Experiment took place in a 32. Birds aligned themselves to the 33 when it was changed.
Magnetic field: Chemicals in birds’ 34 become sensitive to magnetism when exposed to 35. As a result, north and south appear 36 to birds. Magnetite found on the 37 of birds. Magnetite allows birds to sense strength of magnetic field.
Sense of smell: Blocking birds' sense of smell with 38 made them less 39 at navigating over the sea.
Previewing: Preventing 40 to familiar places showed birds use natural features to navigate.
Answers & Explanations Summary
| # | Answer | Evidence | Explanation |
|---|---|---|---|
| Q27 | vii | They seem able to use the position of the sun and stars, the Earth's magnetic field, smells and even landmarks to find their way, depending on which is available to them during the journey | Excerpt/Passage Explanation: The passage explains that birds can use many things—like light, magnetic forces, scents, or physical objects on the ground—to help them travel safely. Answer Explanation: The answer, which is vii (Ways used to navigate migration routes), means that Section B explains the different tools or methods birds use to find the right direction when they travel long distances. Reason For Correctness: The correct answer is vii because Section B acts as an introduction to how birds find their way. The passage states that birds have a 'variety of methods' and 'different geopositioning strategies.' It specifically lists several tools like the sun, stars, magnetic field, smells, and landmarks. This matches the heading 'Ways used to navigate migration routes' because 'ways' is a synonym for 'methods' or 'strategies.' |
| Q28 | ii | When the chicks of migrating birds are born, they imprint, or intuitively learn, the map of the sky and stars as they grow in order to orientate themselves | Excerpt/Passage Explanation: The passage explains that when baby birds are born, they learn the positions of the stars and the sky while growing up so they can find their way later. Answer Explanation: The answer is the heading 'Memorising the sky for migration purposes'. Reason For Correctness: The correct answer is section C because it describes how young birds learn to remember the patterns of the stars and the sky. The text uses words like 'imprint' and 'intuitively learn', which mean the birds 'memorise' the sky to find their way during travel. It also mentions an experiment with a planetarium that proves birds watch and remember the position of stars to know where to go. |
| Q29 | iii | One possibility is that they use the Earth's magnetic field. How they do this is a mystery because the field is so weak. However, experiments have pointed to evidence that birds use the magnetic field in two ways | Excerpt/Passage Explanation: The passage explains that there is a chance birds use the Earth's magnetic field to help them travel, and it mentions that tests have found two different ways birds might use this power. Answer Explanation: The answer means that Section D of the text is about how birds use the Earth's natural magnetic force to find their way during travel. Reason For Correctness: The correct answer is 'iii' because Section D focuses completely on how birds might navigate using the Earth's magnetic field. The text explains that birds may have special chemicals in their eyes to 'see' the magnetic field or a material called 'magnetite' in their beaks to 'feel' it. By using terms like 'magnetic field', 'magnetic north', and 'magnetism', the section provides details specifically about this navigation method. |
| Q30 | vi | There is also some evidence that birds use their sense of smell to find their way across long distances The birds could find their way normally when they approached land where aromas and odours are present but were less efficient at finding their direction over the sea, suggesting that smell is very important for them in piloting their routes |
Excerpt/Passage Explanation: The passage says that researchers found proof that birds use their noses to travel. It explains that birds travel better when they can smell things from the land and struggle when they cannot, which shows that smells are very important for guiding them. Answer Explanation: The answer vi means that the main topic of Section E is how research proves that birds use smells to help them find their way during travel. Reason For Correctness: The correct answer is vi because Section E focuses entirely on the theory and testing of a bird's sense of smell as a tool for direction. It uses words like 'sense of smell', 'aromas', and 'odours', which are all synonyms for 'scents'. The section details an experiment where birds with a blocked sense of smell were 'less efficient at finding their direction', which serves as the 'evidence' mentioned in the heading. |
| Q31 | viii | It seems that birds may build up a visual memory of landmarks that allows them to successfully navigate around places they have already visited. Birds that migrate in daylight often follow natural features like mountains, rivers and lakes. It has even been suggested that they follow man-made features such as roads | Excerpt/Passage Explanation: The passage says that birds remember landmarks from their previous travels. They use these memories of natural things (like mountains) and human-made things (like roads) to find their way across the land during the day. Answer Explanation: The answer viii means that Section F explains how birds use landmarks and locations they already know to help them fly over land. Reason For Correctness: The correct answer is viii because Section F focuses on 'visual clues' and the 'familiar area map'. It explains that birds remember specific 'landmarks' they have seen before. These landmarks include natural objects on land, such as mountains and rivers, as well as man-made things like roads. The section highlights that birds use these known memories to successfully travel through places they have visited in the past. |
| Q32 | planetarium | In one famous experiment, Stephen Emlen placed Indigo buntings in a planetarium, where patterns of stars and planets are projected onto the ceiling | Excerpt/Passage Explanation: The passage states that during a well-known test, a scientist named Stephen Emlen put birds inside a room that shows pictures of stars and planets. Answer Explanation: The answer refers to the specific building or room where scientists conducted the study on birds. Reason For Correctness: The correct answer is 'planetarium' because Paragraph C describes a specific experiment performed by Stephen Emlen. In this experiment, he placed birds known as Indigo buntings inside a planetarium (a theater used for showing the night sky) to test how they react to star patterns. This directly matches the part of the notes asking where the experiment took place. |
| Q33 | sky map | When the stars were projected in different positions, the birds changed position according to the new sky map, thus showing their awareness of the position of the stars | Excerpt/Passage Explanation: The passage explains that when researchers changed where the stars were shown, the birds moved themselves to match that new arrangement of the sky. Answer Explanation: The answer refers to a layout or picture of where stars and planets are in the sky, which birds use to find their direction. Reason For Correctness: The correct answer is located in Paragraph C. It describes a scientific study where birds were put in a planetarium. Scientists moved the images of stars on the ceiling to different spots. The text says that when these stars were moved, the birds moved their bodies or 'aligned' themselves to follow the new 'sky map.' This experiment proved that birds recognize and use the stars to navigate. |
| Q34 | retinas | Researchers have discovered receptors, or chemicals, in their retinas and it is thought that these enable birds to sense the direction of the magnetic north | Excerpt/Passage Explanation: The passage says that scientists found tiny things called receptors or chemicals inside the birds' eyes (the retinas), which they believe help the birds know where north is. Answer Explanation: The answer refers to the part of the eye, called the retina, where scientists found special chemicals. Reason For Correctness: The correct answer is 'retinas' because the passage explains that birds use the Earth's magnetic field to navigate, and one way they do this is through 'receptors' or 'chemicals' found in that specific part of their eyes. The text mentions that these chemicals help the birds feel or see the direction of magnetic north. Therefore, the retinas are the location where these chemicals are found. |
| Q35 | light | When these chemicals are exposed to light, they generate electrons that are sensitive to magnetism | Excerpt/Passage Explanation: The passage states that when light reaches the special chemicals in a bird's eye, it creates a reaction that allows the bird to notice magnetic forces. Answer Explanation: The answer is light, which is the brightness that comes from the sun or a lamp and allows living things to see. Reason For Correctness: The correct answer is light because the passage explains that birds have certain chemicals in their eyes (retinas). These chemicals do not react to magnetism all the time; they only become sensitive to it when they are touched by light. This process helps the birds use the Earth's magnetic field to find their way during migration. |
| Q36 | different | If this is the case, north and south could look different to migratory birds, in effect allowing them to 'see' the magnetic field | Excerpt/Passage Explanation: The passage suggests that for birds that travel long distances, the directions of north and south do not look the same; they look unique or distinct from one another. Answer Explanation: The answer 'different' describes how the directions north and south look to birds when they use their vision to sense the Earth's magnetic field. Reason For Correctness: The correct answer is 'different' because the text explains a theory about how birds use magnetism to navigate. It says that birds have chemicals in their eyes (retinas) that react to light and magnetic forces. Because of this reaction, the birds' vision changes depending on which way they are facing. The passage explicitly states that north and south 'could look different' to them, which likely helps them decide which direction to fly. |
| Q37 | beaks / beak | Scientists have found magnetite on the beak of some birds | Excerpt/Passage Explanation: The passage explains that researchers located a substance called magnetite on the mouth-part of certain birds, which helps them feel the Earth's magnetic pull. Answer Explanation: The answer is beak(s), which refers to the hard, pointed outside part of a bird's mouth. Reason For Correctness: The correct answer is 'beak(s)' because the text discusses how birds use the Earth's magnetic field to help them find their way. In paragraph D, the passage mentions a specific molecule called magnetite that helps birds sense magnetism. It clearly states that scientists have discovered this material on that specific part of the bird's body. |
| Q38 | chemicals | Researchers in the UK, Spain and Italy experimented on seabirds by temporarily blocking their sense of smell using chemicals and then tracking their paths home | Excerpt/Passage Explanation: The passage explains that scientists from several countries did a test on birds. They used certain substances, called chemicals, to stop the birds from smelling for a short time to see if they could still find their way. Answer Explanation: The answer 'chemicals' refers to the substances researchers used to stop birds from using their sense of smell during a scientific study. Reason For Correctness: The correct answer is found in Paragraph E, which explains an experiment regarding the birds' sense of smell. To test if smell helps birds find their way, scientists 'blocked' (meaning they stopped) the birds' ability to smell by using chemicals. This matches the note which mentions blocking the sense of smell with a specific substance. |
| Q39 | efficient | The birds could find their way normally when they approached land where aromas and odours are present but were less efficient at finding their direction over the sea, suggesting that smell is very important for them in piloting their routes | Excerpt/Passage Explanation: The passage explains that while birds found their way fine near land, they were not as good (meaning they were 'less efficient') at choosing the right path over water when they couldn't smell. Answer Explanation: The answer means that the birds were not as good at finding the right direction when they could not use their sense of smell. Reason For Correctness: The correct answer is 'efficient' because the text describes what happened when scientists stopped birds from using their sense of smell. Paragraph E notes that when their smell was blocked, the birds were 'less efficient at finding their direction' while flying over the ocean. This shows that they were not as capable or skillful at navigating without smell. The word 'efficient' here describes how well they could do their job of flying home. |
| Q40 | visual access | 'Previewing' experiments, where birds were allowed or denied visual access to a familiar site before releasing them, indicated that they use a 'familiar area map' | Excerpt/Passage Explanation: The passage states that in specific tests called 'previewing' experiments, researchers either let birds see or stopped them from seeing a place they knew. This helped scientists understand that birds use their memory of what things look like to navigate. Answer Explanation: The answer means being able to see a certain place or object. Reason For Correctness: The correct answer is found in paragraph F, which discusses 'previewing' experiments. The text mentions that birds were either allowed or 'denied' (prevented) from having 'visual access' to a place they already know. This experiment proved that birds create a mental map of what an area looks like to help them travel. Keywords to notice are 'denied,' which means the same as 'preventing,' and 'site,' which is a synonym for 'place.' |