Bird Migration
Read Bird Migration and check the IELTS Reading answers. Birds have many unique design features that enable them to perform such amazing feats of endurance. They are equipped with lightweight, hollow bones, intricately designed feathers providing both lift and thrust for rapid flight, navigation sy…
Passage preview
Birds have many unique design features that enable them to perform such amazing feats of endurance. They are equipped with lightweight, hollow bones, intricately designed feathers providing both lift and thrust for rapid flight, navigation systems superior to any that man has developed, and an ingenious heat-conserving design that, among other things, concentrates all blood circulation beneath layers of warm, waterproof plumage, leaving them fit to face life in the harshest of climates. Their respiratory systems have to perform efficiently during sustained flights at altitude, so they have a system of extracting oxygen from their lungs that far exceeds that of any other animal. During the later stages of the summer breeding season, when food is plentiful, their bodies can accumulate considerable layers of fat, to provide sufficient energy for their long migratory flights.
Vocabulary from this passage
10 words worth learning before you sit the test, each with the sentence it appears in.
- accumulate verb
To gather or acquire an increasing number or quantity of something over a period of time
Migratory birds must accumulate significant fat reserves to survive long-distance journeys across oceans.
- calibrate verb
To adjust or mark an instrument so that it can be used for accurate measurement
Birds use the plane of polarized light at sunset to calibrate their internal biological compasses.
- conducive adjective
Making a certain situation or outcome likely or possible; helping to bring about
The cool and stable night air is highly conducive to sustained and efficient migratory travel.
- far-flung adjective
Spanning a great distance or located in remote and widely scattered areas
Arctic terns travel to far-flung southern latitudes every year to escape the northern winter.
- ingenious adjective
Showing remarkable cleverness, originality, and inventiveness in design or execution
The ingenious heat-conserving design of the bird allows it to survive in the harshest polar climates.
- necessitate verb
To make something necessary as a result or consequence of a particular situation
The extreme distance of the migration route necessitates an annual round trip of several thousand miles.
- phenomenal adjective
Remarkable or exceptional, especially to an extraordinary degree; exceeding common expectations
Birds demonstrate phenomenal powers of navigation, returning to the same nest site from thousands of miles away.
- presage verb
To be a sign or warning that a typically unwelcome event is about to happen
The sudden change in barometric pressure can presage an improvement or decline in local weather conditions.
- sensory perception noun
The process by which organisms receive and interpret stimuli through their physical senses
The avian brain possesses a superior sensory perception compared to humans for detecting magnetic fields.
- sustained flight noun
The act of flying continuously for an extended duration without stopping or resting
The bird's respiratory system is uniquely adapted to provide oxygen during periods of sustained flight.
Answers with explanations
- 14. iv
The paragraph lists specific biological traits like **hollow bones**, **intricately designed feathers**, and specialized **respiratory systems**. These are internal and external **physical characteristics** that explain the mechanics of how birds are able to fly long distances. This matches the heading regarding anatomy. Answer: iv.
- 15. v
The text explicitly identifies the **fundamental reason** for migration as the search for **adequate food** during winter. It explains that while many species can handle cold, they cannot handle a lack of nutrition. This focuses purely on the primary cause or **main reason**. Answer: v.
- 16. ii
This section highlights the mystery of birds flying past **suitable habitat** to reach much more distant locations. Since these closer areas would provide food, the choice to continue for thousands of miles constitutes an **unexplained rejection** of those **closer feeding grounds**. Answer: ii.
- 17. x
The paragraph describes how **young birds**, like cuckoos, migrate successfully despite having **no parental guidance** or teaching. The text describes this innate ability as a **mystery** because they inherit a map they have never seen. This aligns with the heading about migration without teaching. Answer: x.
- 18. vii
This paragraph discusses specific **experiments** and scientific **evidence** regarding how birds navigate. It mentions tools like the **sun**, **stars**, and **magnetic fields**. These details represent current **research findings** on the mechanisms of navigation. Answer: vii.
- 19. i
The focus here is on the **skill** of timing the departure. It mentions that birds react to **pressure changes** and weather patterns to decide when to leave. Finding the **right time** to set off is synonymous with selecting the **best moment** to migrate. Answer: i.
- 20. viii
The passage provides an example of birds being pushed off course by **tailwinds**. Despite the potential **trouble of wind**, the text notes they **arrive safely** and some even return the following year. This illustrates success despite adverse weather conditions. Answer: viii.
- 21-22: AC
21: Option A is correct. The text explicitly states that birds often **journey much further** than is strictly **necessary** for survival. This directly matches the idea that they fly past suitable habitats to reach distant wintering grounds. Other options incorrectly claim all birds travel in families or that only shorebirds resist wind.
22: Option C is correct. The passage notes that flying at night helps avoid **dehydration** caused by the sun. Reduced dehydration implies the birds **need less water** during the journey compared to flying in sunlit skies. Option D is wrong as the text says their perception is different/superior, not necessarily 'sharper' in a visual sense.
- 23. parental guidance
The blank requires a noun phrase. The text states that cuckoos and other young birds find their way **without** help from their parents, using the term **parental guidance**. This phrase fits syntactically and accurately completes the summary of the cuckoo example. Answer: parental guidance.
- 24. compass
The blank requires a noun representing a tool or object for orientation. The text explains birds obtain directions from the sun and stars similar to how a **compass** works. The word **compass** is the correct singular noun that fits the context of identifying directions. Answer: compass.
- 25. daytime predators
The blank requires a noun phrase for something birds want to avoid. The text lists the avoidance of **daytime predators** as a specific benefit of nocturnal migration. The term **daytime predators** fits the grammar and context of the sentence perfectly. Answer: daytime predators.
- 26. visible
The blank requires an adjective to modify 'signs'. The passage explains that birds detect weather changes even before humans can see them, specifically before there is any **visible** sign. This word captures the essence of their sensitive barometric detection. Answer: visible.