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From traffic and aircraft to construction and urban development, human noise is altering how birds communicate, feed and reproduce, according to a large global review published Wednesday.
The study, published in Proceedings of the Royal Society B, reviewed research conducted since 1990 on 160 bird species across six continents.
By pooling data from nearly four decades of scientific studies, researchers found consistent evidence that human-made noise alters bird behaviour and reduces reproductive success.
Birds use sound a lot to get by in their daily lives. They use songs for territorial defence and mate attraction and alarm calls to alert other birds of predators.
Chicks use vocal signals to prompt feeding. When those signals are masked or distorted by background noise, key behaviours can change.
“They use song to find mates, calls to warn of predators, and chicks make begging calls to let their parents know they’re hungry,” said lead author Natalie Madden, who conducted the research while at the University of Michigan.
“So if there’s loud noise in the environment, can they still hear signals from their own species?”
The review found that noise pollution severely affects communication, risk-taking, foraging, aggression and physiology.
It also influences habitat use and is linked to lower reproductive success in some species.
“We found that noise significantly impacts communication risk behaviours, foraging, aggression and physiology and had a strong effect on habitat use and a negative impact on reproduction,” the report read.
According to the study, noise exposure in some cases interrupted mating displays, led males to alter courtship songs or masked communication between chicks and parents. These disruptions were associated with reduced reproductive success.
The effects varied among species. Birds nesting close to the ground experienced greater negative impacts on reproduction, while species with open nests showed stronger effects on growth.
Birds living in urban areas were also found to have higher levels of stress hormones than those in less developed environments.
The authors described noise pollution as an underexamined component of human impact on biodiversity.
The International Union for Conservation of Nature reported in October that 61 percent of the world’s bird species are in decline.
Senior author Neil Carter, also of the University of Michigan, said measures to reduce noise exposure already exist, including building materials and designs that can dampen sound.
“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.
“We know what to use and how to use it, we just have to get enough awareness and interest in doing it.”
