Noise pollution is affecting bird behavior across the globe, disrupting everything from courtship songs to the ability to find food and avoid predators, a large-scale new analysis showed on Wednesday.
Researchers reviewed nearly four decades of scientific work and found that noises made by humans were interfering with the lives of birds on six continents and having "strong negative effects" on reproduction success.
Previous research on individual species has shown that single sources of anthropogenic noise -- such as planes, traffic and construction -- can affect birds as it does other wildlife.
But for this study, the team performed a wider analysis by pooling data published since 1990 across 160 bird species to see if any broader trends could be established.
The study, published in the journal Proceedings of the Royal Society B, found clear evidence of a "pervasive" impact of noise pollution on birds worldwide.
"We found that noise significantly impacts communication risk behaviors, foraging, aggression and physiology and had a strong effect on habitat use and a negative impact on reproduction," AFP quoted it as saying.
This is because birds rely on acoustic information to survive, making them particularly vulnerable to the modern din produced by cars, machinery and urban life.
"They use song to find mates, calls to warn of predators, and chicks make begging calls to let their parents know they're hungry," Natalie Madden, who led the research while at the University of Michigan, said in a statement.
"So if there's loud noise in the environment, can they still hear signals from their own species?"
In some cases, noise pollution interrupted mating displays, caused males to change their courtship songs, or masked messages between chicks and parents.
The study included many common species such as European robins and starlings, house sparrows, and great tits.
The response varied between species, with birds that nest close to the ground suffering greater reproductive harm, while those using open nests experienced stronger effects on growth.
Birds living in urban areas, meanwhile, tended to have higher levels of stress hormones than those outside of cities.
Some 61 percent of the world's bird species have declining populations, mostly due to habitat loss driven by expanding agriculture and logging, the International Union for Conservation of Nature said in October.
The study authors said that noise pollution was an "underappreciated consequence" of humanity's impact on nature, especially compared to biodiversity loss and climate change.
But some relatively simple fixes could make a big difference for birds, they said.
Madden told AFP that shifting from noisier cars and landscaping tools such as mowers and leaf blowers to electric-powered alternatives was one idea.
Another could be "running machinery outside peak breeding seasons, avoiding activity when birds are migrating through an area, or shifting construction away from habitats that support vulnerable species", she added.
Buildings could also be adapted to muffle sound in the same way they are constructed to improve visibility and minimize bird collisions, said the study's senior author Neil Carter, from the University of Michigan.
"So many of the things we're facing with biodiversity loss just feel inexorable and massive in scale, but we know how to use different materials and how to put things up in different ways to block sound," he said.
