Artificial light attracting birds towards cities, becoming cause of death

A recent study utilizing weather radar data has revealed a startling attraction of migratory birds to artificial lights. Kyle Horton, the lead author and a professor at Colorado State University’s Department of Fish, Wildlife and Conservation Biology, warns that city lights could be ensnaring birds in an unintended snare.

Published in Nature Communications, the research highlights the challenges faced by migratory birds in urban environments, including deadly building collisions, habitat loss, food scarcity, and increased threats from humans and predators like cats. While urban parks offer potential rest stops, they also force birds to vie for scant resources.

Migration is a perilous and exhausting journey for birds, often spanning thousands of miles and resulting in significant weight loss. Suitable rest and feeding spots are crucial for their survival and successful arrival at their destinations.

Bird Migration: Perilous, Exhausting Journey

Horton likens these stopovers to fuel stations for travelers, emphasizing their importance for the birds’ migratory journey. Without adequate rest and nourishment, migration could be jeopardized.

"Cities pose multiple risks to migrating birds," said co-author and Michigan State University Professor Geoff Henebry. "They also offer resources for the tired birds to rest and refuel. Our study is notable in that it combines big data—and a lot of processing—from the weather surveillance radar network with big data from multiple space-borne sensors to address key questions regarding the influence of urban areas on bird migration."

The research analyzed over 10 million radar observations alongside various local factors to understand the birds’ choice of resting spots. Out of 49 predictors, light pollution emerged as the second most significant factor drawing birds to these areas.

While altitude serves as a key indicator of flight patterns, it does not clarify the birds’ motivations. Migratory patterns detected by radar often align with coastlines or specific elevations. However, light pollution stands out as the primary human-related factor influencing bird migration.

This study emphasizes the necessity of considering how urbanization affects wildlife and necessitates a reevaluation of artificial lighting usage, in order to guarantee the safety and well-being of migratory birds.

Unexpected danger to birds

A conservation dilemma has sparked by the allure of city lights to birds: Should we safeguard urban areas as vital stopover habitats, or should we focus on lights-out initiatives in them? Kyle Horton and his team are collaborating with volunteers and government bodies to navigate this complex issue, balancing the aesthetic and social demands for illumination against its ecological impacts.

Light pollution extends beyond aesthetic concerns, disrupting human circadian rhythms and contributing to health issues such as depression, insomnia, heart disease, and cancer. Horton emphasizes that light should be considered a pollutant, impacting all facets of life.

Birdcast, a joint project between CSU, the Cornell Lab of Ornithology, and the University of Massachusetts, offers a solution. This tool provides migration forecasts and real-time radar data, enabling individuals to receive alerts about incoming bird flocks and identify critical nights for minimizing light pollution.

Mitigation strategies include retrofitting windows with decals to prevent bird collisions and adjusting lighting by dimming brightness and opting for warmer colors like red, orange, and yellow, which are less disruptive to wildlife compared to bright white or blue light.

The Federal Aviation Administration has also adapted its guidelines for communication towers, which historically used continuous red or white lights as aircraft warnings. These lights caused birds to circle the towers and collide with the supporting wires. In response to conservation research, the FAA mandated the use of flashing red lights in 2016, significantly reducing bird strikes.

This multifaceted approach underscores the importance of considering the ecological consequences of urban lighting and the need for proactive measures to protect migratory birds during their perilous journeys.

Closing button to help feathered friends

The tragic incident at Chicago’s McCormick Place Convention Center, where a large number of birds perished due to light pollution, is a stark reminder of a widespread issue. Kyle Horton points out that such mass fatalities, involving 100 or more birds, are far from rare. In the United States, it’s estimated that nearly one billion birds fatally collide with buildings each year.

During the unfortunate event on October 4–5, the majority of the victims were songbirds, with 33 different species identified by the Chicago Field Museum. These birds play a crucial role in our ecosystem by consuming pests that damage crops and gardens, aiding in pollination, and dispersing seeds.

Horton suggests that raising public awareness about nocturnal bird migration could be a significant step towards safeguarding them from the dangers of light pollution. The solution to this complex problem may be surprisingly straightforward for avian welfare.

"Horton said, "Turning off all lights tonight would immediately and positively impact the birds by preventing any collisions due to lights."

A new report in Scientific Reports looked at how city lights affect 298 kinds of birds. The report says that while we know birds hit buildings because of the lights, some birds are more likely to crash than others. This means that the bright lights at night might be more dangerous for certain birds that fly at night.

Another study found that some birds, called ‘super colliders’, hit buildings more often. An article by Audubon explained that birds that make noise at night when they fly are more likely to hit buildings. When these birds get mixed up by the bright lights, they call out more, which can bring more birds from their group and cause more crashes.

Saving Seabirds from city Lights

City lights disorient seabirds like petrels and shearwaters at night, leading to injuries. Global studies reveal these birds often crash into structures or land and struggle to fly again, risking predation, vehicular accidents, or death from hunger or thirst.

The scientists say we need to learn more about this because many seabirds are in danger of disappearing. It’s not easy to just turn off all the city lights, but researchers are trying to find ways to keep the lights we need and still protect the birds.

Some cities are worse for birds than others, especially if they have lots of glass buildings and bright lights. Big buildings can be really dangerous. A study from the Cornell Lab of Ornithology says that Chicago, Houston, and Dallas are some of the riskiest places for birds flying through.

In Salt Lake City, there’s a promise people can make to turn off lights they don’t need at night during the times when birds are flying through the most. Tracy Aviary is also studying how light pollution affects birds in the area.

The Audubon Society is working hard to help birds too. They found out that when birds get confused by lights, they use up a lot of energy flying around and calling out. This makes them tired and more likely to get hurt in other ways. In New York City, they found that turning off bright lights sometimes helps birds fly away from buildings and not crash into them.

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