Jonny Rogers explores how noise pollution is harming marine life, forcing birds to change their behaviour and preventing human flourishing.
Photo by Gary Bendig
Pollution is often discussed as toxic substances accumulating in natural environments and causing harm to living creatures, plants and landscapes. However, a growing body of research is showing that high levels of manmade sound – referred to as noise pollution – can have a comparable negative impact on many animal species, with potentially severe consequences for entire ecosystems.
Sound plays a crucial role in communication for many forms of life, serving as a part of mating rituals and warning calls, as well as the detection of both predators and prey. However, anthropogenic (i.e. human-generated) noise is polluting the Earth’s auditory ocean, as it were, harming marine life, forcing birds to change their behaviour, and preventing humans flourishing.
The Ecology of Noise Pollution
In the early 2000s, large numbers of giant squid became stranded on beaches across the west coast of Spain. Although it wasn’t immediately evident what had caused their death, it was speculated that it might have something to do with powerful sound pulses from ships prospecting for petroleum beneath the seafloor. As later research confirmed, low frequency noise harms the bodies of cephalopods and other marine life, and also disorients creatures which depend on sound to navigate environments (such as dolphins and whales).
The effect of noise pollution on bird populations around the world has also been widely reported. A study from 2007, for example, showed that European robins in urban environments with a high levels of sound during the day-time are more likely to sing at night (an unnatural practice), and another study from 2017 concluded that increased noise reduces the diversity of bird species in neotropical urban parks.
As with marine life, anthropogenic sound has been found to change the behaviour of birds. Some species, such as great tits, are found to sing at higher frequencies to ensure that they can be heard above the predominantly low-frequency city noises, and zebra finches become less faithful to their partners and unable to acquire new motor skills when exposed to human traffic, thereby potentially altering the population’s evolutionary trajectory.
As you might expect, disturbing animal populations can have a serious impact on the wider ecosystem, even including plant species. A recent study from California Polytechnic State University has shown that long-term noise pollution limited the ‘seedling recruitment’ of pinyon pine and juniper trees. By comparing the diversity of vegetation in locations with persistent high levels of noise – caused by 15 years of continuous natural gas well extraction – with those in which the noise had been removed, the researchers concluded that industrial activity was driving away species of birds and other creatures responsible for disseminating seeds.
This research is notable for having shown that noise pollution can have a residual and long-term effect; the removal of the sources of noise did not guarantee the recovery of the local tree species or bird populations. As the paper’s lead author, Jennifer Philips, explains:
“Animals like the scrub jay that are sensitive to noise learn to avoid particular areas. It may take time for animals to rediscover these previously noisy areas, and we don’t know how long that might take.”
However, it is important to recognise that not all species of birds are affected by anthropogenic noise in the same way: for example, white-crowned sparrows in San Francisco were found to have returned to their previous frequencies after the streets quietened when the U.S. first went into lockdown last year.
A Silent Protest
If this evidence alone does not motivate action, the effect of noise pollution on human health should warrant serious concern, not to mention greater political attention. As many as one in five Europeans are currently exposed to harmful sound levels due to road traffic, with this statistic set to increase in the coming decades.
As personal experience alone might testify, exposure to high levels of noise is closely associated with increased stress, sleep disturbance and impaired cognitive performance. However, studies have also observed a connection between environmental noise and a variety of cardiovascular problems including heart failure and stress-induced vascular damage, as well as obesity and diabetes. Children are particularly vulnerable, with exposure to noise from road and air traffic being linked to impaired reading and oral comprehension.
Although large-scale change must involve effective policy and urban planning, we all have an obligation to care for the people, species and environments that surround us, as well as ourselves. Avoiding playing music in public, speeding through neighbourhoods on motorised vehicles or maintaining a garden for extended periods of time is a reasonable first step, though even limiting how much you listen to loud music through headphones might avoid long-term adverse health effects.
Nevertheless, the recent study from California Polytechnic State University adds to the growing body of evidence showing that the ecological impact of human activity is far greater than we often acknowledge, and certainly extends beyond simply what we can see. Although research on the long-term effects of noise pollution is currently limited, what is yet to discover is often as much a cause for concern as what is known. As Professor Clint Francis concludes:
“In essence our research indicates that the consequences of noise are far-reaching and reverberate throughout the ecosystem through lots of species.”
Of course, noise – like many other forms of pollution – is largely an unintended by-product of activities either justified by convention or necessitated by the economic, technological and social demands of the modern world. However, if you were to discover that something you are doing is both harmful and avoidable, then refusing to change your behaviour is a moral choice – one that is complicit in our mutual self-destruction.
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