By Natalie Sopinka
Each morning on my walk to the University of Ottawa campus, I am surrounded by a mosaic of noises. From the quiet thoughts in my head to the crisp crunching of leaves (now snow) beneath my boots. But perhaps the most extraordinary sounds that surround me emanate from the road: the blaring honk of a truck backing up, the squealing of a van’s tires spinning forward through a puddle, and the constant, humming din of cars flowing into the downtown.
But my ears aren’t the only ones exposed to such noise. I look up from the sidewalk and spot a house sparrow. Does he hear the noises too?
As the number of cars and roads increases, so does the evidence that traffic and urban noises can change the behaviour and physiology of birds.
A recent study led by David McClure at Boise State University found that migratory birds are sensitive to the sounds of traffic too. The research team played recorded traffic noises through speakers set up in the Idaho Bird Observatory field site, a stopover spot for migratory birds. Over 8000 observations confirmed that birds, including species familiar to the OFNC (e.g., American robin, red-breasted nuthatch, yellow warbler, cedar waxwing), avoided areas when traffic noise was being emitted from the speakers. Replenishing energy supplies and resting are critical during lengthy migrations. If there is ample noise pollution surrounding stopover habitat, birds may forgo stopping which could compromise successful migration.
Other work has shown that passerine bird densities are reduced in areas of Alberta’s boreal forests impacted by oil and gas infrastructure, particularly when noisy compressor stations are in operation. Great tits living along noisy highways in the Netherlands produce clutches with fewer eggs. When exposed to urban noises before sunrise, spotless starlings and house sparrows start their dawn chorus earlier in the morning, perhaps because they were woken early from their slumber.
Noise pollution also affects other animals and insects. Boat propellers, submarine sonar, and underwater mining, gas, and oil exploration can all disturb aquatic wildlife that use sound to feed, flee from predators, and find mates. Even grasshoppers change the frequency of their calls when living along busy roads.
Understanding how animals respond to noise pollution can help us determine which factors may be driving declines in wild populations, and why. The research can also inform conservation managers about which habitats are important to protect from urban noise, and how we can ensure that noise pollution doesn’t reduce the quality of already protected areas.