Every year, millions of migratory birds cross the night skies of North America on an extraordinary journey that can last weeks, if not months. This journey, spanning thousands of kilometres, can however be hindered by light pollution, which risks disorienting the birds, causing deviations in migratory routes and increasing the risk of collisions with buildings and skyscrapers. To counter this phenomenon, the people of Texas have decided to adopt a simple yet effective measure: switching off unnecessary lights during evening hours in migration periods, from March to June and from August to November.

Migratory birds in Texas

Texas is one of the main migratory routes for millions of birds, including the robin, the hummingbird, and the northern warbler. Each year, approximately 2.5 million birds cross the Texas region during their migration: roughly 1 in 3 birds in spring and 1 in 4 in autumn that migrate over the United States pass through Texas.

According to the Cornell Lab of Ornithology, the National Audubon Society and other research institutions working on biodiversity and the conservation of migratory birds, light pollution is one of the leading causes of death among migratory birds, with approximately 1 billion birds dying every year in the United States as a result of collisions with illuminated buildings, skyscrapers and transmission towers.

Migratory birds navigate at night using the position of the stars and the natural brightness of the sky. Artificial lights disorient them, causing them to dangerously veer off their natural course. In recent years, several Texan cities have adopted policies to reduce light pollution during migration periods and have backed awareness campaigns, such as Lights out, Texas!. Non-essential lights, such as those in offices and on skyscraper facades, are switched off or dimmed to prevent them from confusing the birds.

Switching off the lights to help birds migrate

A significant example of this initiative comes from Houston, where the public spaces management authority collaborated with local skyscrapers to switch off lights between midnight and 6 in the morning during migration seasons. This simple gesture led to a reduction in building collisions of around 25 per cent since the measure was introduced, as reported in a study conducted by the Cornell Lab of Ornithology. In Dallas, another Texan city, the same strategy brought about a decrease of around 30 per cent in collisions with taller buildings.

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This action has also proven effective in protecting vulnerable species. The hummingbird, for example, which migrates every year from areas of North America to Mexico, has been particularly affected by light pollution. Artificial lights frequently disorient the small birds, which, drawn towards illuminated buildings, crash into glass facades. With the adoption of lights-off policies, a significant improvement has been observed in the migratory routes of these delicate species.

The initiative has also had a positive impact at a global level, as other major international cities, such as Toronto and New York, have begun to follow Texas's example, creating a movement to protect migratory birds through simple yet decisive actions. Switching off non-essential lights is, in fact, a practical and low-cost solution that reduces not only the risk to birds, but also energy consumption and light pollution.

Overall, the commitment of Texans to protecting migratory birds through the reduction of light pollution is an example of how even everyday actions can have a positive impact on biodiversity. By simply switching off the lights, it is indeed possible to ensure that millions of migratory birds can migrate safely. In an era in which pollution and climate change increasingly threaten wildlife, initiatives such as this are a fundamental step towards a more sustainable future.