Although Earth Day comes once a year, it is important to make every day bird-friendly. There is already a heavy loss of avian life, with a decline of around 2.9 billion birds since 1970, and it would be calamitous if this trend were to continue. The following are five types of pollution to keep in mind and their detrimental effects on class Aves:

Air Pollution

*Great Egret*
*Robert Amoruso/Audubon Photography Awards*

Air quality is a key social determinant of health, not only for humans, but even more so for birds. Birds consume a great deal of oxygen, especially in flight, and have a quicker breathing rate than us. Their respiratory system is designed to be highly efficient, where air travels unidirectionally: when a bird first inhales, their breath travels to an air sac at the back of the body. When they exhale, that same puff of air goes to the lungs. When a bird breathes in a second time, the initial breath moves from the lungs to an air sac at the front of the body. The second exhalation releases that air out of the animal.

In-depth analysis demonstrates that regulations to decrease air pollution actually helped save about 1.5 billion birds. The Environmental Protection Agency’s nitrogen oxides trading program, which ran from 2003-2008 and was later replaced by a different program, diminished the level of tropospheric ozone, which helped drive up bird populations, especially for small landbirds such as warblers, robins, and chickadees. Ozone, when in the stratosphere, helps block out harmful sun rays. However, when it is in the troposphere, or the area between the Earth’s surface and the stratosphere, it is a health hazard. Not only can it impair respiratory and immune systems, but it can also negatively affect the insects and plants that birds feed on and shelter in. Sources of ozone at the ground level include vehicle, cleaning supply, and paint fumes. Although the above mentioned air quality improvements were meant to help us, they benefited avian wildlife as well. This goes to show how connected we all are on this planet.

Water Pollution

*Photo by Tim Mossholder (timmossholder* *on Unsplash)*

When the sun is shining, many Chicagoans make their way to beaches that outline Lake Michigan. The city is lucky to have this Great Lake as a border. But contaminants in the water could be making birds sick. As wetlands disappear and can no longer act as a giant filter, dirty water known as runoff flows into the lake. Runoff could include oil, pesticides, fertilizers, and nitrates. Per- and polyfluoroalkyl substances, or PFAS, are ‘forever chemicals’ developed for water/stain resistant products. PFAS have pervaded water sources, and their presence escalates the risk of cancer and developmental disorders for birds and humans alike. Moreover, these substances can be passed from mother to progeny, lowering the chance of survival for young offspring.

Plastic Pollution

*Photo by Muhammad Ali (muhammadali33308* *on Unsplash)*

Plastic is everywhere, all around us. It contains the food we eat, packages the gadgets we buy, and encases the cars we drive. It is also found floating in water, between blades of grass, and in the bodies of birds. When pieces of plastic look like food, birds will eat it and feel full, causing them to miss out on getting enough nutrients. Ingested plastic can also damage kidneys and the endocrine system, leading to a shortened lifespan. It may even seem obvious to an observer that a bird has eaten too much plastic—it looks emaciated and sapped of energy.

New research has shown that even healthy-looking birds may be adversely affected by plastic. Adults may provide pieces of plastic mistaken for food to their young. It was found that if Sable Shearwater chicks are fed too much plastic, neurodegeneration, cell rupture, and deterioration of their stomach lining can result. Blood tests showed that young birds in this position had drastic health issues, with protein patterns similar to patients with dementia. However, these animals did not look sick, which underscores the invisible pervasiveness of this plastic scourge.

Besides being confused for food, plastics are also dangerous because they can leach chemicals such as biphenyl, which may cause endocrine disruption. Fishing lines can also entangle birds, as they are unable to see the thin, translucent plastic. They become incapacitated when this string wraps around their wings or limbs. People can help end plastic pollution by cutting down on the amount of plastic in our purchases, recycling when plastic is used, and volunteering for beach and water clean-ups.

Noise Pollution

*Tree Swallow, chicks*
*Barbara Krizman/Audubon Photography Awards*

While litter is obviously destructive to the environment, there are some less visible types of pollution that can affect wildlife. Noise is one, light is another. How birds hear may seem a bit of a mystery as they don’t have visible ears sticking out. Rather, they possess funnel-shaped ear openings normally found just below and behind their eyes. Scientists have discovered that the head’s structure causes each eardrum to register sound at a different frequency, allowing the bird to parse out where sound is coming from.

Good hearing is imperative for birds as they use this sense for hunting and avoiding threats, as well as for communicating. Barn Owls, for instance, rely almost completely on their ears while hunting. When birds are unable to effectively use their ears due to excessive noise in the environment, they rely on their eyes instead. Constantly scanning their surroundings means less time for foraging and feeding, a detrimental trade-off. Too much sound can also mean fragmented sleep, increased stress, and depressed immune function. For some, noise-induced anxiety may lead to lower reproductive success.

As an area gets louder, birds may either increase their own volume or sing at a higher pitch. If there is too much noise exposure, some species will simply avoid that location, leading to a loss of diversity and joy those birds can bring. Vehicles, aircraft and lawnmowers are major culprits of human-created noise. It can help our feathered neighbors to rethink our transportation, use a rake, and take some time to enjoy birdsong and recognize how beautiful the sounds of nature are.

Light Pollution

*A dead Blackpoll Warbler, victim of a glass collision*
*Sydney Walsh*

When nearly 1,000 birds died hitting the windows of McCormick Place in one night in 2023, the convention center became internationally infamous. A key reason why so many birds perished is that the 2.6 million-square-foot building left too many lights on, a perfect example of the harm light pollution can cause.

Research has shown that birds are attracted to artificial light, and excess brightness during the night has affected where birds fly, sometimes to their demise, as they encircle towers of light until they exhaust themselves or crash into well-lit windows.

Light pollution can also affect songbird reproduction, including when they nest and how many eggs are laid. This could mean that in areas with light pollution babies are hatching when food is still scarce. But there is an unexpected silver lining here—because climate change is causing some areas to heat up sooner, nutrient sources may actually be available around the time chicks emerge from their shells. However, finding ways to reverse both light pollution and climate change would be best.

The world would be far worse without birds, and it is up to us to keep their populations stable or growing by holding air, water, plastic, noise, and light pollution in check. As an additional benefit, pollution reduction is healthful for humans too. These five types are just some of the issues that trouble birds, but every beneficial action matters.

Sources

Air:

How does reducing air pollution help birds?

Conservation cobenefits from air pollution regulation: Evidence from birds - PMC

What is Ozone? - Utah Department of Environmental Quality

How Do Birds Breathe And The Efficient Respiratory System Of Birds – Birdfy

https://www.britannica.com/science/respiratory-system/Birds

Birds suffer from air pollution, just like we do | Audubon California

Air pollution as a social and structural determinant of health - ScienceDirect

NOx Budget Trading Program | US EPA

Water:

Protecting Water Quality from Agricultural Runoff