Scientists make concerning discovery after studying behavior shift in prolific bird species: 'An alarm signal'

Great tits in urban environments produce fewer offspring compared to their forest-dwelling counterparts due to light pollution, reported SwissInfo.

What's happening?

A new Swiss study found these birds become restless at night in brightly lit city areas, causing them to warm their eggs less consistently.

Scientists from the Sempach Ornithological Institute compared hatching rates between forest and city nesting boxes to understand human impact on breeding birds.

The results revealed a stark contrast: great tits in darker forest environments warm their eggs throughout the night, leading to more successful hatches. In urban areas, however, the birds get more restless the brighter their surroundings are, which means less time warming their eggs.

Great tits are common throughout Europe, the Middle East, Central Asia, and parts of North Africa.

"The fact that even common and well-adapted birds such as the great tit have problems with nocturnal light is an alarm signal," noted researchers from the ornithological station in their press release.

Why is light pollution concerning?

This disruption affects more than just great tits. Light pollution hampers the natural behaviors of many wildlife species, with potentially cascading effects through ecosystems.

For migratory birds returning from wintering grounds, excessive artificial lighting dulls their sense of direction, especially during foggy or cloudy nights when they rely on seeing stars for navigation.

Less adaptable nocturnal animals like owls and bats face even greater challenges. These creatures evolved in darkness and depend on night environments for hunting, breeding, and survival.

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When their habitats become artificially brightened, their entire life cycles can be thrown into disarray.

For humans, the loss of bird populations could mean fewer natural pest controllers and reduced biodiversity in our communities.

What's being done about light pollution?

The Sempach Ornithological Institute recommends "full cut-off lights" as a solution. These specially designed fixtures direct light downward without emitting any light above the horizontal plane, reducing light intensity without compromising human safety or visibility.

Communities worldwide have begun implementing dark-sky policies that limit unnecessary outdoor lighting. Simple changes like using motion sensors, timers, and proper shielding on outdoor fixtures can make a big difference.

If you own a home, you can help by turning off your outdoor lights when they aren't needed, using warm-colored LED bulbs (which have less impact on wildlife), and installing proper shields on security lights to prevent upward light spillage.

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