Bird Migration
Read Bird Migration and check the IELTS Reading answers. Birds are highly mobile and among the swiftest of living creatures. Flight gives them the power to move in any direction for as long as they have the energy to keep going. They are equipped with lightweight, hollow bones, a finely-tuned navig…
Passage preview
Birds are highly mobile and among the swiftest of living creatures. Flight gives them the power to move in any direction for as long as they have the energy to keep going. They are equipped with lightweight, hollow bones, a finely-tuned navigation system and an ingenious heat-conserving design that allows them to face life in the harshest of climates. Their respiratory systems have to perform efficiently during sustained flights at altitude, so they have evolved a system of extracting air from their lungs that far exceeds that of any other animal. These features enable birds to come and go with the seasons. On the way, they face constant danger and a daily requirement to find food, water and a safe place to rest. So why do millions of birds migrate rather than stay in one place?
Vocabulary from this passage
7 words worth learning before you sit the test, each with the sentence it appears in.
- apparent conundrum noun
A confusing problem or puzzle that seems difficult or impossible to solve or explain
The apparent conundrum of rising employment alongside falling consumer spending puzzled several leading economists.
- conducive adjective
Creating suitable conditions that help make a particular outcome likely or possible
A quiet and orderly classroom environment is highly conducive to academic achievement and focused learning.
- mounting evidence noun
A gradually increasing body of facts and observations that supports a particular claim
Mounting evidence indicates that excessive smartphone usage impairs memory retention in secondary school students.
- presage verb
To act as a sign or warning that a particular event will happen
Sharp decreases in manufacturing orders usually presage an impending economic slowdown across the manufacturing sector.
- seasonally abundant adjective
Existing in very large amounts or quantities only during specific times of the year
Coastal economies depend heavily on seasonally abundant tourist revenue during the brief summer period.
- sensory perception noun
The ability to notice, understand, and react to physical stimuli through natural senses
Advanced flight simulators stimulate human sensory perception to replicate turbulent weather conditions for pilots.
- single-handedly adverb
Done alone and without any help or assistance from other people
The chief engineer single-handedly drafted the comprehensive safety protocols for the newly constructed facility.
Answers with explanations
- 14. ii
Paragraph A outlines the anatomical adaptations that enable birds to undertake migration. The author highlights **lightweight, hollow bones**, navigation abilities, heat conservation, and specialized **respiratory systems**, summarizing that **these features enable** seasonal movement. This detailed catalog of anatomical traits directly matches the heading concerning physical characteristics. Other headings fail because the paragraph introduces physiological adaptations rather than migration timing or specific navigation experiments.
- 15. iv
Paragraph B explains why bird migration takes place, opening with the topic sentence that the explanation **revolves around food**. It details how birds travel to exploit resources that are **seasonally abundant** and depart when supplies become scarce. This focus on nutritional necessity matches the heading specifying the primary driver of migration. The heading about choosing the right moment is incorrect because paragraph B explains the fundamental reason for migrating rather than departure timing.
- 16. x
Paragraph C addresses the mystery of why certain birds travel much further than necessary. The text emphasizes that species **overfly areas** of suitable habitat, creating an **apparent conundrum** that remains unexplained. This central theme corresponds to the heading regarding the unexplained rejection of nearer habitats. The heading discussing problems with wind does not apply here because wind hazards are addressed later in the passage, not in this discussion of route distance.
- 17. vi
Paragraph D focuses on how juvenile birds reach their destinations without instruction. The author asks how young birds travel **without parental assistance** and uses young cuckoos as an example of making journeys **single-handedly** after being raised by foster parents. This evidence aligns with the heading describing successful migration despite a lack of teaching. Headings about navigation mechanisms are too broad, as paragraph D specifically addresses the absence of parental guidance.
- 18. v
Paragraph E discusses scientific investigations into avian navigation. The author cites **mounting evidence** and **experiments** showing how birds compute sensory inputs like the sun, stars, polarized light, and magnetic fields to steer. This synthesis of scientific trials aligns with the heading on research findings about orientation. The heading on departure timing does not fit because paragraph E focuses on navigation mechanisms and nocturnal flight benefits rather than when to start.
- 19. i
Paragraph F discusses the crucial decision of departure timing. The text states that a safe arrival depends on **setting off at the right time**, requiring birds to detect subtle changes in **barometric pressure** to anticipate cold snaps and thaws. This focus directly corresponds to the heading on choosing the ideal moment to migrate. The heading regarding physical adaptations is too general, as the paragraph specifically concentrates on weather forecasting for departure.
- 20. ix
Paragraph G examines how birds cope when blown off course by harsh weather. While strong winds cause casualties, the author notes a **silver lining** where North American birds blown across the Atlantic **arrive safely in Europe** and return home. This balance of hazard and survival matches the heading on achieving success despite wind difficulties. The heading about larger birds utilizing wind is a distractor that ignores the focus on transatlantic drift and survival.
- 21-22: AC
21: The question asks which statements are true regarding bird migration. Scanning paragraph C reveals the **puzzling fact** that many species journey **much further than would be necessary** to secure food and favourable conditions, flying past perfectly adequate intermediate habitats. This statement directly supports the option about birds migrating longer distances than necessary. The distractor claiming family groups migrate most successfully is contradicted in paragraph D, which states adults rarely accompany offspring.
22: Paragraph E outlines the advantages of nocturnal flight, explicitly noting that night travel lowers the **danger of meeting predators** and reduces the **risk of dehydration** caused by flying in warm sunshine. Lowering dehydration risk means birds conserve moisture and need less water during flight. This evidence supports the option stating birds require less water when flying at night. The distractor claiming birds cannot survive when separated from their species is refuted by solitary cuckoo migrations.
- 23. parental
The sentence requires an **adjective** modifying 'guidance'. The prompt's phrase **lack of** corresponds to the passage's **without parental assistance**. Scanning paragraph D for cuckoo behavior locates the discussion of juveniles migrating alone without their parents. The word **parental** is lifted verbatim from the text, fits the grammar before 'guidance', and meets the one-word limit.
- 24. predators
The gap follows 'contact with' and requires a **plural noun** representing a hazard avoided at night. The prompt's phrase **avoid contact with** paraphrases the passage's **danger of meeting**. Scanning paragraph E for benefits of nocturnal travel identifies the reduced threat of attack. The noun **predators** is taken directly from the text, fits the syntax of the sentence, and complies with the one-word limit.
- 25. visible
The gap precedes 'clues' and requires an **adjective** describing how birds detect weather shifts. The prompt's phrase **without clues** corresponds to the passage's **before there is any visible sign of them**. Scanning paragraph F for barometric sensitivity leads to this observation. The adjective **visible** is extracted verbatim from the passage and fulfills the one-word requirement.
- 26. lost
The gap follows 'thought to be' and requires an **adjective or participle** describing historical assumptions about disoriented birds. The prompt's phrase **in the past** matches **not so long ago the assumption was**, while **flying in the dark** corresponds to **a dark windy night**. Scanning paragraph G locates the phrase 'hopelessly lost'. The word **lost** is extracted verbatim and satisfies the one-word limit.