Impact on different species • Sea turtle hatchlings may move inland instead of towards the [33] __________. • Some bats avoid well-lit areas, making it harder for them to [34] __________.
Community and environmental solutions • Warmer, amber-coloured [35] __________ are less disruptive than white or blue light. • Lamps should shine [36] __________ onto roads and pathways. • Some towns introduce lighting [37] __________ in parks and near nature reserves. • Motion sensors can reduce light [38] __________ when areas are empty.
Actions at home • People can reduce indoor light by closing [39] __________ at night.
Overall message • Small changes can have a big [40] __________.
Part 4: You will hear a lecture on an environmental topic.
Artificial light has become one of the most powerful but least noticed environmental changes of the modern age. As cities, towns, and transport networks continue to expand, natural darkness is disappearing across much of the world. For humans, light provides safety, comfort, and the ability to extend daily activities into the night. For wildlife, however, this constant brightness represents a major disruption to natural rhythms that developed over millions of years. Many species depend on predictable cycles of light and dark to guide feeding, movement, breeding, and rest. These cycles are part of their natural rhythms. When those cycles are disturbed, the effects can spread through entire ecosystems. This disruption can affect not just one species, but the relationships between many species.
One of the most obvious examples can be seen in insects. Many night-flying insects use the moon and stars to keep a straight line while travelling. Artificial lights confuse this navigation system, causing insects to circle street lamps, building lights, or advertising signs until they become exhausted. Large numbers die from stress, dehydration, or predators. Because insects form the base of many food chains, their decline affects birds, amphibians, reptiles, and even some mammals. This means that a simple street light can indirectly influence the survival of many other species.
Birds are also strongly affected by artificial lighting, particularly during migration. Many species travel long distances at night, using natural light patterns to orient themselves. Bright city lights and illuminated buildings can attract them off course, causing them to collide with glass structures or circle endlessly around tall buildings. This wastes valuable energy and can lead to injury or death. Over time, repeated disruptions may reduce breeding success and contribute to population decline. Even small changes to timing and direction can have serious consequences during migration.
Marine wildlife faces similar dangers. One of the most well-known cases involves sea turtles. Newly hatched turtles normally move toward the ocean by following the brightest horizon, which under natural conditions is the reflection of moonlight on the sea. In coastal areas with strong artificial lighting, hatchlings often mistake street lamps or hotel lights for the ocean and crawl inland instead. Many die from dehydration, vehicles, or predators before they can reach the water. Conservation groups now work closely with coastal communities to reduce lighting during nesting seasons.
Mammals are not immune either. Bats, which rely on darkness to hunt safely, may avoid well-lit areas because they feel exposed to predators. This reduces the amount of habitat available to them and can force them to travel longer distances for food. Other bat species may gather around lights because insects collect there, changing natural competition patterns between species. These changes may seem small, but they can gradually reshape entire ecosystems.
Fortunately, solutions exist that allow humans to enjoy the benefits of lighting while reducing harm to wildlife. One important step is choosing the right type of light. Warmer, amber-coloured bulbs are less disruptive than bright white or blue light, which strongly affects many animals. Another key measure is controlling the direction of light. Lamps should shine downwards onto roads and pathways instead of spreading into the sky, rivers, or trees.
Shielding is another effective technique. By placing covers around lights, communities can prevent unnecessary light from spilling into natural areas. Some towns have introduced lighting curfews in parks and near nature reserves, turning off or dimming lights late at night when fewer people are present. Motion-sensor systems can also reduce light levels when areas are empty, then increase brightness briefly when someone approaches. These approaches save energy as well as reducing the impact on nearby habitats.
Individuals can contribute as well. Closing curtains at night, turning off unused lights, and choosing low-impact outdoor lighting all help reduce light pollution. When many people take these small steps, the combined effect can be significant. In other words, small changes can have a big effect.
In conclusion, artificial light is far more than a convenience. It is a powerful environmental force that affects insects, birds, marine animals, and mammals alike. By understanding these impacts and making thoughtful choices, societies can protect wildlife while still maintaining safe and functional night-time spaces.
Public awareness is growing, and schools, local councils, and environmental groups are beginning to include light pollution in their education programs. As technology improves, new lighting systems will continue to become more efficient and less harmful to surrounding habitats. If action is taken now, future cities can be designed in ways that respect both human needs and the natural world.
