Noise Pollution Alters Bird Behavior

song bird
It takes no observational feat to notice that people enjoy birds. As human developments dominate the landscape and evict so many of our wild neighbors, we spend a disproportionate amount of our energies coaxing the birds, specifically, back. Why else the feeders and birdhouses and baths so common to neighborhood backyards? Perhaps the exact reasoning for our admiration is best explored by poets or philosophers, but our feathered friends seem to be pleasant reminders of our connection to the natural world.

Those species that graciously remain in our cities and towns are being forced to make some behavioral changes. To circumvent the din of honking horns, plane engines, and other deafening hallmarks of modern living, birds are changing how they vocalize. It shouldn’t come as a surprise, given what other things we’ve done to throw a wrench in avian existence.

Already, the abundance and distribution of bird species is heavily influenced by humans. This is clear in the effects that habitat loss has on avian biodiversity, with 85% of threatened bird species at risk due to habitat conversion for human activity. (see “Habitat conversion and global avian biodiversity loss”) It is also easily observable in major cities, where those species that cope well with anthropogenic disturbance predominate – think pigeons, sparrows, and starlings. Others may become extinct or extirpated (extinct within a particular region) if they fail to quickly adapt, such as in India, where urbanization is preventing some birds from nest-building. Global climate change can shift delicate ecological balances, restructuring community fauna and upping the risk of extinction. In California, for instance, a variety of bird species may be displaced as a consequence. (source)

Noise pollution may not seem like a big deal when compared to land clearing or climate change, but birds rely heavily on singing to communicate. Birdsong is used to attract mates, defend territory from rivals, and even warn for predators. This means that a bird’s ability to be heard plays a direct role in its reproductive interactions and survival. Birdsong is particularly noticeable in the early hours of the morning, a phenomenon known as the “dawn chorus.” Scientists aren’t precisely sure why birds select this time of day for their vocal exertions, but it may have something to do with the quiet, calm surroundings – sound travels well when there’s little wind and excess racket.

It’s the excess racket part that humans are contributing to, prompting some species to sing at different times and in different ways. In Mexico, researchers found that house finches raised the pitch of their lowest song notes in response to road noise, and also held them for longer. A study published in Current Biology examined song changes in the great tit across ten European cities – including Paris, London, and Amsterdam – finding that in each location the birds omitted the low-frequency portion of their call. (source) For the great tit, this makes plenty of adaptive sense, since most urban noise is low-frequency. Why expend the energy to belt out your alto if no one else can hear it?

bird singing
A green-headed tanager checks itself out in the side-view mirror of one of noise pollution’s culprits. Photo by Joanne Williams / Rex Features.

Another species has opted to sing at times when it is least likely to be interrupted by the sounds of human transportation. European robins studied in Sheffield, England, were found to sing at night in those areas where daytime noise levels were significantly higher than those at night – a behavioral change previously attributed to light pollution. German nightingales, by contrast, are content to engage in the bird equivalent of screaming. To cope with the urban cacophony, they’ve started singing at a piercing 95 decibels. The intensity is like standing a few feet away from a running chainsaw, and the sound is enough to damage human ears if sustained.

bird singing
The little Nightingale packs quite a sonic punch. Photo from the BBC.

However helpful such biological tricks may be for some birds, the nearer one gets to a densely populated town or city, the less diverse the avian community becomes. Not all species have the vocal machinery to work around the commotion. House sparrows, which have a significant low-frequency component to their songs, have suffered population declines of two thirds in Great Britain over the past few decades. (source) A university of Colorado at Boulder study found that mourning doves and black-headed grosbeaks in New Mexico avoid nesting near sites where natural gas is being extracted, as they cannot tolerate the noisy compressors. Only 21 different species resided in the noisy sites, compared to 32 in the quiet ones. And although the scrub jay, a songbird predator, was likewise driven away by the compressors’ noise, its absence could have radiating effects on the local ecosystem. Scrub jays are responsible for the dispersal of pine nuts in Southwest woodlands, and so their absence could reduce abundances of pinyon pine and alter ecological relationships.

Many of us have grown accustomed to the hustle and bustle of the 21st Century, but the birds may have a lesson to teach us about the value of peace and quiet: just how frighteningly little of it remains.

According to Gordon Hempton, an audio ecologist, fewer than five minutes go by before the average patch of wilderness is interrupted by the sounds of human interference. Hempton defines natural silence as “the complete absence of all audible mechanical vibrations, leaving only the sounds of nature at her most natural.”

After years of recording the natural environment in places all around the globe, Gordon estimates that fewer than a dozen truly silent places are left. It is not just the birds that are vulnerable, either. The breeding success of some Australian frog species is being impacted by Melbourne traffic noise, and ocean noise pollution caused by boat engines and undersea drilling are interfering with habitat selection in young corals. Who knows what variety of species may be affected? Noise might seem an unlikely player on the ecological stage, but further study is definitely warranted on impacts of the anthropogenic racket.


Written by Marisa Buxbaum


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  1. Hi,

    An airport is proposed for Western Sydney – Australia. ALL incoming flights and many outgoing flights are to fly over the world heritage area of The Blue Mountains and its National Parks, at low altitudes – 5,000 ft to 10,000 ft above sea level AND WITHOUT CURFEW. This area is already 750 ft to 3,000 ft above sea level. Although there is a local outcry, very few Australians are concerned. Your article touches on the potentially huge impacts on biodiversity in the area.

    Any pressure to stop this airport is appreciated.

    Regards, Deb Jones

  2. The text below is excerpted from the current version (2016/2017) of the Pierce County Code Chapter 8.72. My purpose is to make people aware that the laws stated here actually are the current law in Pierce County, in the state of Washington. It seems there is a lack of awareness of these laws. Are you SICK AND TIRED of seeing and hearing the noise-making behaviors described below, WHICH THE LAW EXPLICITLY STATES ARE ILLEGAL? Contact the government and law-enforcement and DEMAND THAT THEY ENFORCE THE LAW!

    8.72.040 Mufflers. It is unlawful for any person to operate, or for any owner to permit any person to operate, any motor vehicle or motorcycle upon the public highways which is not equipped with a muffler in good working order and in constant operation.
    8.72.070 Exhaust System. It shall be unlawful for any person to operate any motor vehicle upon any public highway if the vehicle exhaust system exceeds the maximum permissible sound levels set forth below for the category of vehicle, as measured at a distance of twenty inches (0.5 meter) from the exhaust outlet under procedures established by the State of Washington in Washington Administrative Code Chapter 173-58-080, “Close Proximity Exhaust System Sound Level Measurement Procedure.” Motorcycles 99 dB(A)/Automobiles, light trucks, and all other motor vehicles 10,000 pounds or less 95 dB(A).
    8.72.090 Public Disturbance Noises. It is unlawful for any person to cause, or for any person in possession of property to allow to originate from the property, a public disturbance noise. The following sounds are public disturbance noises:…
    C. Frequent, repetitive, or continuous sounds from starting, operating, repairing, rebuilding, or testing of any motor vehicle, motorcycle, dirt bike, or other off-highway vehicle, or any internal combustion engine, within a rural or residential district, including vacant property adjacent thereto, so as to unreasonably disturb or interfere with the peace, comfort, and repose of owners or possessors of real property…
    F. Any loud and raucous sound made by use of a musical instrument, whistle, sound amplifier, or other device capable of producing or reproducing sound which emanates frequently, repetitively, or continuously from any building, structure or property, such as sound originating from a band session, tavern operation, or social gathering and which unreasonably disturb or interfere with the peace, comfort, and repose of owners or possessors of real property in the area affected by such noise…
    H. Public disturbance noise from portable or motor vehicle audio equipment: While in park areas, residential or commercial zones, or any area where residences, schools, human service facilities, or commercial establishments are in obvious proximity to the source of the sound, it is unlawful for any person to negligently cause, make, or allow to be made from audio equipment under such person’s control or ownership the following:
    1. Sound from a motor vehicle or vessel sound system, such as a tape player, radio, or compact disc player, which is operated at such a volume that it could be clearly heard by a person of normal hearing at a distance of 50 feet or more from the vehicle or vessel itself;
    2. Sound from audio equipment such as a tape player, radio, or compact disc player, which is operated at such a volume that it could be clearly heard by a person of normal hearing at a distance of 50 feet or more from the source of the sound;
    8.72.120 Enforcement… C. The Sections of this Chapter relating to motor vehicles and vessels and noise emanating from vehicles and vessels, shall be subject to enforcement proceedings with or without a citizen’s complaint.
    8.72.130 Violation – Penalty. A. Any person violating any motor vehicle performance standard of this Chapter, or who shall create, keep, maintain, or allow to occur any noise related to motor vehicle performance standards, as defined herein, shall be guilty of a misdemeanor.

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