Next time you’re about to say something stupid, think twice: you might be responsible for decline in bird populations. New studies show that noise pollution is a source of habitat degradation. We all know that we have an impact on the environment and the communities around us, but how deep does our impact dig? Scientists Heidi Ware, Christopher McClure, Jay Carlisle, and Jesse Barber conducted an experiment to find out. Their article, entitled “A phantom road experiment reveals traffic noise is an invisible source of habitat degradation,” found that traffic noise was a big issue in dereasing animal populations.
Past research showed that “bird populations decline within 1km of human infrastructure, including roads.” Qualitative data and observation pointed towards traffic noise as the main reason for this decline. To test this, the researchers set up speakers along a ridge in Southwest Idaho in order to test the effect of traffic noise on songbird communities. The speakers blared traffic noise on and off, alternating every four days throughout fall migration. This was compared with another site without speakers; birds flying across the site were counted and quantified.
Though sixty-nine percent of birds remained despite the noise, there was a marked difference in the two sites. The birds must have been as annoyed by the sounds as a New York tourist would be; capture rate decreased by almost one-third during the times that the traffic noise was on.
In addition to measuring the frequency of bird flight, researchers measured body condition index, which can represent large ecological and conditional changes even by minute changes. In the control area with no noise, the health of the songbird community was at a “suitable” level. In noisy areas, the health declined significantly. Over a quarter of species showed significantly lessened BCI in noisy situations.
Why does this happen? According to the study, results were primarily because of decreased foraging and vigilance. Prey search “time, sleep, or territoriality” impacted this: prey might leave areas with increased noise, which leaves the monitored species with no food! Additionally, the noise could compromise a predator’s ability to hunt by making prey harder to hear and letting prey sneak away. This could make it virtually impossible for a predator to find prey— and no one likes going hungry.
The study showed that though one would expect birds to adapt and habituate by increasing visual vigilance or agility, they really don’t. “During energetically demanding periods in a bird’s life, increasing vigilance can reduce survival because of increased starvation risk,” the researchers found. Birds must rely on poor eyesight to get them their prey. In addition to incapacitating these birds, the noise literally stresses them out. So much. The paper said that though unlikely, the noise could pose a physiological stress to the species that eventually caused decline in body condition.
When put under stress, birds are caught between a rock and a loud place. They must either remain in an area with potentially detrimental loud noise and incur physiological costs, or leave and disrupt their patterns of migration. And roads aren’t the only place our noise has impacted species and their habitats. Other loud activities, such as natural gas extraction and simply suburban living, are shown to have an impact on species, especially those who migrate. Migratory species need special protection of habitats in “breeding, wintering, and stopover locations.” Bottom line? The noise is getting out of hand.
To be sure, there is more to this than the malicious hurting of bird species! Building roads is a huge part of infrastructure and helping the globalization of networks. It’s not easy to keep suburban populations quiet, nor would it be strategically beneficial. It’s important to understand the effect noise pollution has and keep it in our minds when going into the realm of policymaking and public information-sharing.
The researchers emphasized the need for us to pay more attention to noise impacts. Noise pollution is an invisible evil: it degrades habitats and negatively impacts the species in the area but the effect isn’t visibly seen. Thus, it doesn’t do well in the human conservation eye. We need to grasp the impact our noise has on these birds and work on policies and measures to both raise awareness and regulation of the noise. So remember: next time you make some noise, make sure you’re making noise by speaking up about this widely overlooked issue of noise pollution and habitat degradation!
Biological Sciences – Ecology: Heidi E. Ware, Christopher J. W. McClure, Jay D. Carlisle, and Jesse R. Barber A phantom road experiment reveals traffic noise is an invisible source of habitat degradation PNAS 2015 112 (39) 12105- 12109; published ahead of print August 31, 2015, doi:10.1073/pnas.1504710112