雅思阅读 082: Lights Out — How Darkness Saves Migrating Birds

Adapted from "How darkness might save migratory birds" by K. R. Callaway, Scientific American, 24 April 2026.

🎧 课文朗读音频（约 50 秒）

Reading Passage

Between March and June, millions of migratory birds head north along North America's flyways, navigating by starlight, moonlight and Earth's magnetic field. But as cities have grown brighter, that ancient journey has become increasingly dangerous.

Migratory birds fly at night, using specialised cells in their eyes that can sense the planet's magnetic field. They also take visual cues from faint celestial light. Artificial light from windows, street lamps and floodlights disrupts this carefully tuned navigation system, disorienting birds and sometimes trapping them in bright beams for hours.

Each year, an estimated one billion birds die from window collisions in the United States alone. Countless more exhaust themselves circling lit skyscrapers, or dive into glass they cannot see. For species already declining because of climate change, habitat loss and pesticides, light pollution is one threat that ordinary people can actually do something about.

"Unlike changing climates, which individuals can't influence as much as we'd like, we can truly help with the overnight lighting problem," says evolutionary ecologist S. K. Winnicki of Ohio State University.

When and How to Help

The number of birds overhead peaks two to four hours after sunset during spring and autumn migration. On those heavy migration nights, experts advise simply turning off unnecessary lights and closing curtains or blinds. For outdoor lights that must stay on, they recommend pointing them downward or fitting shields so they shine away from the sky.

Forecast maps published by BirdCast, a project run by Cornell and Northeastern universities, show when large numbers of birds are expected over a given area. Communities across the US — from New York to Chicago to Austin — now run "Lights Out" programmes that ask building managers to switch off non-essential lighting during migration peaks.

Daytime dangers remain too. Birds looking for green space to rest may collide with glass facades that reflect trees or sky. "Everyone has walked into glass at some point," says Dustin Partridge of the NYC Bird Alliance. "It hurts our ego, but for a bird it's lethal. They are going full speed headfirst, and they don't perceive glass."

Simple measures can reduce daytime collisions: external markers such as a grid of dots on the outside of windows, or ultraviolet coatings that birds can see but humans cannot.

A Solvable Problem

Light pollution is not the biggest threat birds face, but it is unusual because it can be reduced almost immediately, without new technology or large public spending. Turning off a few lights at night costs nothing and can save thousands of lives.

"It's tough to be a bird," Partridge says. "We've built up cities in their path, and this presents risks. But those issues are things that can be easily fixed."

Questions 1–5

Choose the correct letter, A, B, C or D.

1. How do migratory birds primarily navigate at night?

   • A. They follow rivers and coastlines.
   • B. They use starlight, moonlight and magnetic sensing.
   • C. They follow other bird species.
   • D. They rely on landmarks remembered from previous years.

2. Approximately how many birds die from window collisions annually in the US?

   • A. One million
   • B. Ten million
   • C. One hundred million
   • D. One billion

3. When are birds most vulnerable to light pollution during a 24-hour cycle?

   • A. At dawn
   • B. Two to four hours after sunset
   • C. At midday
   • D. At midnight

4. What does BirdCast provide?

   • A. A list of endangered bird species
   • A. Forecast maps of bird migration activity
   • C. A database of bird sightings
   • D. A bird-watching guide

5. Why is light pollution described as unusual?

   • A. It affects only birds.
   • B. It can be reduced quickly at low cost.
   • C. It is caused only by skyscrapers.
   • D. It is not a real threat.

Questions 6–10

Do the following statements agree with the information?

Write:

• TRUE
• FALSE
• NOT GIVEN

6. Birds use magnetic cells in their eyes to navigate.
7. Closing curtains helps prevent interior light from spilling outside.
8. Ultraviolet coatings on windows can reduce bird collisions.
9. Light pollution is the largest threat to migratory birds.
10. All major US cities have mandatory lights-out laws.

Questions 11–13

Complete the sentences. Choose NO MORE THAN TWO WORDS from the passage.

11. Artificial light can ________ birds in bright beams.
12. Outdoor lights should be pointed ________ or fitted with shields.
13. Birds may collide with glass that ________ trees or sky.

Answers

1. B — "using specialised cells… sense Earth's magnetic field and take visual cues from the faint light of the moon and stars."
2. D — "one billion birds die by colliding with windows."
3. B — "reaches its peak between two and four hours after sunset."
4. B — "forecast maps… show when large numbers of birds are expected."
5. B — "it can be reduced almost immediately, without new technology or large public spending."
6. TRUE — "specialised cells in their eyes that can sense the planet's magnetic field."
7. TRUE — "close curtains or blinds to keep interior illumination from spilling outside."
8. TRUE — "ultraviolet coatings that birds can see but humans can't."
9. FALSE — It is "not the biggest threat birds face."
10. NOT GIVEN — Programmes exist but mandatory laws are not mentioned.
11. trap
12. downward
13. reflects

Key Vocabulary