# Bird Migration Theory

IELTS Academic Listening - 10 questions - 10 minutes - Note completion

Source: Recording, questions and answer key from Cambridge IELTS 17, Test 3, Listening Part 4. © Cambridge University Press & Assessment. Used for educational practice. Explanations and evidence notes are written by Testmigo.

## The recording

8 minutes of audio. Practice it with the player on the page; the transcript is on the answers page.

## Questions

### Questions 31-40: Note completion

Complete the notes below. Write ONE WORD ONLY for each answer.

Bird Migration Theory
Most birds are believed to migrate seasonally.
Hibernation theory
It was believed that birds hibernated underwater or buried themselves in **(31)** _____.
This theory was later disproved by experiments on caged birds.
Transmutation theory
Aristotle believed birds changed from one species into another in summer and winter.
In autumn he observed that redstarts experience the loss of **(32)** _____ and thought they then turned into robins.
Aristotle's assumptions were logical because the two species of birds had a similar **(33)** _____.
17th century
Charles Morton popularised the idea that birds fly to the **(34)** _____ in winter.
Scientific developments
In 1822, a stork was killed in Germany which had an African spear in its **(35)** _____
previously there had been no **(36)** _____ that storks migrate to Africa
Little was known about the **(37)** _____ and journeys of migrating birds until the practice of ringing was established.
It was thought large birds carried small birds on some journeys because they were considered incapable of travelling across huge **(38)** _____.
Ringing depended on what is called the '**(39)** _____' of dead birds.
In 1931, the first **(40)** _____ to show the migration of European birds was printed.

[Practice online with a timer and instant marking](https://testmigo.com/ielts/listening/bird-migration-theory) - [Answers and explanations](https://testmigo.com/ielts/listening/bird-migration-theory/answers)