Bird Reproduction No Longer the Same Due to Noise and Light Pollution 

Bird Reproduction No Longer the Same Due to Noise and Light Pollution 

Air pollution is bad, but so are noise and light pollution. They can be worse for the wildlife, too, like our darling birds. According to new research from a team at California Polytechnic State University, those two types pollution are 

Published in Nature, the researchers used NASA satellite data. Then, they got a bird’s-eye view of how noise and light negatively affected bird reproduction in North America. 

They also discovered that these negative factors could mask birds’ responses to the effects of climate change or affect them directly. 

In the last few decades, bird populations have decreased by around 30%. Many had been trying to find out and understand what caused the decline and reverse. 

The answers were right before them: noise and light pollution. Scientists had overlooked both. That is, until recent studies that suggest how those stressors could negatively impact certain types of birds. 

VIIRS technology and data 

The Visible Infrared Imaging Radiometer Suite is an instrument which the NASA launched in 2011. Before it’s development, there was no such thing as large-scale, high-resolution light pollution data. This new study has produced a continent-wide picture utilizing VIIRS data. 

“Our study provides comprehensive evidence that noise and light can profoundly alter reproduction of birds, even when accounting for other aspects of human activities,” said Clint Francis, a biologist and one of the lead authors on the study. 

Researchers looked at a vast collection of data sets. That includes the ones which local scientists collected via the NestWatch Program. Altogether, they assessed how light and noise affected bird species across North America.  

Specifically, they looked at the reproductive success of 58,506 nests from 142 species. Then, they considered several factors for each nest. For instance, the time of year when breeding happened and whether at least one chick went out from the nest. 

Birds’ reproduction coincides with peak food availability to feed their young. They usually breed around the same time per year, taking cues from daylight. 

This study found that light pollution causes birds to begin nesting up to a month earlier than normal in open environments. In forested environments, they could nest up 18 days earlier. 

Warming and pollution 

It may sound fine, but the consequence could be a mismatch in timing. Chicks may hatch before their food is readily available. These early season nests may be less successful at fledging at least one chick. Climate change makes everything more complicated. 

Earth warms up more, and in turn, food is available earlier due to warmer weather. Birds have maintained their historical breeding times because of their internal clocks. When there are changes in daylength, it could result in fewer chicks surviving. Their food source came and went. 

Francis said, “We discovered that the birds that advanced the timing of their reproduction in response to increased light pollution actually have better reproductive success. 

“A likely interpretation of this response is that light pollution actually allows these birds to ‘catch up’ to the shift towards earlier availability of food due to climate change.” 

Therefore, we have two conclusions about birds’ response to climate change. Birds in lit conditions may be tracking climate change better than those in dark areas. This state is, however, temporary. 

Second, birds are not adjusting their reproductive timing to climate change. Instead, they may’ve been responding to light cues since many studies were done in areas exposed to some light pollution. 

Additionally, looking at the noise pollution data, birds living in forested areas tend to be more sensitive to noise. Not so much to ones in open environments. 

Trying to know birds’ responses 

So far, researchers have looked into a more detailed data of 27 different bird species. They explored physical traits that could explain the variations in species’ responses to light and noise. 

A bird’s ability to see in low light and the pitch of its call had a connection to the species’ responses to light and noise pollution. 

When a bird’s eye can take more light, the more that species move its breeding time earlier, in response to light pollution. Additionally, it could lead to more chance of that species benefitting from light pollution with improved nest success. 

Noise pollution delayed nesting for birds’ whose songs are at a lower frequency. That makes it more difficult to hear through low-frequency human noise. Whereas, mating decisions are made based on the male’s song. 

In some cases, females need to hear the male’s song to become physically ready to breed. 

These trait and environment-specific results have strong implications for managing wild lands. Developers and land managers could use this study to understand how their projects could affect birds.  

For example, Francis says, “Is it a forest bird? If so, it is likely that it is more sensitive to light and noise.” 

What the researchers found out is a good first step toward a larger goal: developing a sensitivity index for all North American birds. Consequently, the index allows managers and conservationists in the future. 

Related not-so-good news about other animals 

We haven’t seen birds’ hardships for now. But for the wildlife in Africa, it’s real. During the pandemic, wildlife poaching is on the rise.  

The main cause is, of course, the coronavirus. It’s been holding back organizations devoted to stopping poachers. Damien Mander, the founder of the Zimbabwe-based International Anti-Poaching Foundation. 

“We’ve seen a huge upturn. There’s a fairly steady line there with a dip just before covid and then a rapid upward turn as a result of a downtown in tourism and philanthropic giving,” said Mander, showing a graph charting a steep rise in the recovery of tusks from poached elephants. 

This situation can be good and bad to the wildlife. On one side, some animals can thrive, but on the other, they suffer. COVID-19 has shut down African tourism which funds many conservation activities. 

According to Mander, it’s caused a global economic depression that crushed philanthropic giving to conservation groups. Poachers have stepped into the gaps. 

“It was the way we treated wildlife in the first place that got us into this mess, and now wildlife is suffering again. And while we see bailout packages for humans and cities and countries all over the world, we’re not seeing that for animals,” said Mander. 

Poaching, the root of the pandemic? 

According to Mander, what we’ve got right now may be caused by poaching. In a webinar broadcast this week by EarthX, Mander showed recent video of poached pangolins loaded into the back of a pickup truck. 

These armored mammals are, to Mander, a leading suspect as the intermediate mammal that bridged coronavirus to humans from a similar virus in bats. 

Chinese scientists now say that Wuhan market may have been merely the site of a superspreader event. But the leap from pangolins to human is believed to have occurred at the region’s wildlife market. 

Mander said, “We talk about animals getting into wet markets, and (how) we’ve got to stop and close down the wet markets. Well, the job of a ranger is to stop animals from getting there in the first place.  

“I already thought the job of a ranger was the most important job in the world, but this has made me realize that rangers are the last line of defense not only for nature, but perhaps for humanity.” 



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