Researchers warn that noise pollution is causing chronic stress in birds and that it negatively impacts their health. The study, which was recently published in the Proceedings of the National Academy of Sciences, looked at western bluebirds and the impact that oil and gas operations noise has on them. According to the findings, this constant noise pollution has resulted in stunted growth in chicks, less eggs hatching, and more.
Noise pollution, as with light pollution, is a growing problem. Man-made noises, including the sounds produced by vehicles, construction, and aircraft, are hard to avoid for both humans and wildlife. As with humans, constant exposure to these noises can be stressful, disrupt sleep, and ultimately result in a decrease in health.
Western bluebirds are notable due to their natural tendency to move toward noisy places. One would assume these birds are better suited to withstand constant man-made noises, but the study found the opposite — they’re most severely impacted by the noise pollution. Nests in these areas show fewer eggs that hatch; the resulting chicks experience stunted growth.
Researchers also looked at ash-throated flycatchers and mountain bluebirds, both of which are found breeding near BLM properties containing gas and oil operations. To monitor hatching, the team set up to 240 nesting boxes across a dozen different sites. In addition to monitoring feather length and nestling body sizes, the researchers took note of how successful hatching was. They also took blood samples from chicks and the adult female birds.
Sadly, all three bird species were found to have lower than normal corticosterone stress hormone levels, which isn’t a good thing — this means they’ve experienced endless stress, so much so that normal hormone levels have been disrupted. Similar patterns are found in humans who have experienced extreme stress. As well, the researchers noted that these birds experience excessive spikes in stress hormone when exposed to a stressor, such as someone holding them for 10 minutes.
The reasons for the heightened stress aren’t necessarily due to the sound itself, but in part because it drowns out calls from other birds. This makes it impossible for birds to warn each other about predators in the area, which results in the mother bird staying in a state of vigilance, constantly stressing about the potential of an unknown predator nearby.
The findings raise concern that constant noise pollution could result in decreased bird populations as hatching rates decrease and chicks fail to thrive.
SOURCE: University of Colorado Boulder