Coo-coo. Chika-dee-dee-dee. Tee-ee. Con-cor-ee.
Whether you live on a rural farm, at a cabin in the mountains, in the suburbs or in a major city, chances are you’ve seen and heard birds outside your window today. Among the birds chirping, you may have also heard the rumblings of cars, heavy machinery or even aircraft soaring overhead. But you may have never asked yourself how all that noise affects birds.
Defenders of Wildlife and the University of Michigan set out to answer that question in recent research and understand how common human-made noises affect bird behavior and well-being. Read on to find out what Defenders’ Natalie Madden, lead author of the study and conservation science and policy analyst, learned. What she found just may surprise you!
Why did you focus your study on birds?
Birds are especially vulnerable to noise because of their reliance on acoustic information. Birds use vocalizations to find mates, to warn of predators, to let their parents know they are in need of food and much more.
We also focused on birds because they are found in so many different habitats, including areas typically associated with a lot of noise like cities.
How did you conduct the study?
There has been a recent increase in studies that identify the ways in which noise is affecting animals. These studies often include one or a few species, in a specific context, with a single noise source. It can be difficult to understand the broader impacts when we look at these studies individually.
We collected data from 160 different studies, covering 161 different bird species from across the globe. With a total of 944 data points to analyze, we were then able to identify broader trends within the research.
We categorized the data into nine categories of bird responses to noise. These included both behavioral responses, such as communication, as well as responses directly relating to fitness, or an individual’s ability to survive and reproduce. We wanted to answer, “Are any of these responses different in the presence of human-made noise versus a quiet environment?”
What did you find from the research?
Eight of the nine categories we studied were strongly impacted by noise. These categories included reproduction, communication and habitat use.
Reproduction responses included anything from ability to find a mate, to number of eggs laid and offspring leaving the nest. The communication category included if individuals changed aspects or timing of their songs or calls in the presence of noise, such as the frequency at which they sang or the time they began singing in the morning. Responses within the habitat use category measured whether or not individuals inhabited certain areas when noise was present.
Noise had an overall negative impact on reproduction and significantly changed the way birds communicated and used their habitat. For example, one study found both black-capped chickadees and American goldfinches sang at higher frequencies in areas with a lot of traffic noise versus in areas with little noise.
What noise sources did you study? Were you able to detect whether the type of noise had any impact responses?
Our research included numerous types of human-made noise including urban, industrial, aircraft and even lab-generated noises. We did not find that the type of noise had an effect on the outcome of the research. Overall, birds had the same reaction and responses whether the noise was coming from cars or an aircraft.
What does all of this mean for birds and their populations?
There is a lot of evidence showing bird populations are decreasing. Recent research found of the 261 North American bird species studied, 47% are experiencing population declines and we are seeing an accelerated decline in populations for about 20% of those species.
While our study does not look at the impacts on populations, I think it’s fair to say noise is negatively impacting the fitness of individual birds as well as behaviors that could influence their ability to survive and, therefore, noise likely has some population-level effects. Birds are already facing many threats including habitat loss and climate change, and noise is another threat that has the potential to have long-lasting consequences.
How can I help birds?
All of this information can feel a bit overwhelming, but like many conservation issues, noise can be tackled from numerous angles.
On the largest scale, conservationists and wildlife managers need to take noise into consideration when identifying the threats to animals and what is considered suitable habitat. We sometimes only think about whether habitat meets the basic needs of shelter and food, but it is much more complicated. Exposure to noise should be something we work to minimize with technological advances and management strategies.
As an individual, you can think about how you can reduce the noise you are making at home or in your daily life. This might mean switching to quieter electric lawn tools like mowers and leaf blowers. You might also reduce the amount you drive. Opt to walk or bike instead or even use public transportation if it is available to you. Getting involved in your local politics and incorporating noise dampening initiatives into your community’s policies is another great way to help.
Noise is not the only kind of sensory pollution impacting wildlife. Overuse of artificial lights and pesticides interfere with animals’ senses and behavior. Only turning on essential lights at night and limiting your use of pesticides can additionally help.
At the end of the day, being mindful, making even small changes and encouraging your friends and neighbors to do the same can make a difference for the wildlife near you.
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