There is a growing body of evidence suggesting noise pollution from human activity is harmful to wildlife. Now a new study can be added to the stack. A recently published study in the Proceedings of the National Academy of Sciences (PNAS) found that noise pollution may be hampering birds’ ability to reproduce.
The study found that western bluebirds that built their nests near noisy oil and gas operations laid fewer eggs that hatched and the chicks produced were smaller. The birds examined during the study showed physiological signs of chronic stress from being exposed to the constant noise of the oil and gas operations. The findings were alarming because western bluebirds tend to gravitate toward noisy environments and are thought to be some of the least noise sensitive birds.
The researchers followed three species of nesting birds that breed near oil and gas operations on Bureau of Land Management property in New Mexico for the study. Those species were the western and mountain bluebirds and the ash-throated flycatchers. None of the species studied are endangered.
For three breeding seasons, the team analyzed measurements, hatching success, and blood samples from adult females and their offspring in 240 nest boxes on 12 pairs of sites. Trap doors to access the boxes gave the team a minimally invasive way to capture the birds and take measurements.
The researchers found that the birds nesting in areas with higher noise levels had lower baseline levels of a key stress hormone across all species and life stages. Nestlings from noisy areas that were being held were found to be producing more stress hormones than those bred in quiet nests. They also took longer to return to baseline levels.
Lead author Nathan Kleist conducted the research while at CU Boulder. He graduated with a PhD in evolutionary biology in May. Kleist is now a visiting professor at State University of New York. The other authors of the study included researchers from California Polytechnic State University and the Florida Museum of Natural History. The study was sponsored by National Geographic.
The researchers suspect other species experience similar effects in noisy areas. Kleist likens the sound of an oil and gas compressor to the drone of a highway. Some of the loudest oil and gas producing sites can be as noisy as standing on the tarmac at an airport.