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Newsletter #1

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Hello, Earthlings! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.) This week:

Why birds migrate through cities - and how you can help them succeed

The stone cold truth: Visualizing the loss of Arctic sea ice

The physical and emotional toll of far-off wildfires

Task force calls on Ottawa to spend billions on 'green recovery'

Why birds migrate through cities - and how you can help them succeed

It's fall migration time, which means thousands of bird species from warblers to thrushes to shorebirds are on their way from their breeding grounds in Canada to their winter homes in the U.S., Mexico and Central and South America.

A sizable proportion of them are swooping and fluttering through North America's biggest cities. That includes an estimated 50 million passing by Toronto, according to Andrés Jiménez Monge, co-ordinator of the urban program for the conservation group Birds Canada.

Why do they come through big cities?

The main reason is that birds travel along a series of migration paths or . They navigate along lakes, rivers and coastlines with lots of resources such as food - some of the same features that made these areas attractive for human settlement and led them to become some of the country's biggest cities.

Toronto is at the intersection of two important flyways, Jiménez Monge said.

Another reason many birds fly through cities is that they migrate at night and navigate by the stars, which is why they are attracted to city lights. But cities can be full of dangers for birds.

"It's good that so many people are able to enjoy the birds that fly through here," Jiménez Monge said. "It's good that we can be stewards of these flyways. It's bad in the sense that we are not doing that."

According to FLAP Canada, which aims to protect birds from collisions with human-built structures, 25 million birds fatally collide with windows in Canada each year. It's the second-leading human-related cause of death for birds (after cats).

Cities such as , and have adopted bird-friendly urban design guidelines so developers can help reduce hazards such as window reflections and light pollution.

There are also things individual residents can do, Jiménez Monge says. Here are a few:

Get to know your birds. Knowing which birds are there and what they need can help you to support them. Birds Canada offers online courses, and identification apps are also available. You can also set up a feeder and see what birds show up. Jiménez Monge says the best way to learn is to go out with an experienced birder. Events at local bird festivals are a good place to start.

Make your windows bird-safe. If you live in a highrise, draw the blinds or turn off or reduce lighting at night during migration. During the day, use blinds, strings hanging from the tops of windows, or window treatments such as dots to prevent bird collisions. (FLAP Canada is currently running a contest with prizes for people who do this.)

Re-wild your yard. Reduce the size of your lawn and let part of the yard grow wild. Plant native plants. Create a brush pile to attract insects, which many birds eat. Avoid pesticides.

Keep cats indoors. This also protects felines from hazards such as predators and vehicles.

Report bird sightings for science. Organizations like Birds Canada rely heavily on citizen science data from apps such as and programs such as FeederWatch. "We need to know the status of birds - how they're doing - in order to take the right measures to protect them," Jiminez Monge says.

He encourages people across the country to enjoy migration time.

"We are realizing that cities are a fantastic place to watch the birds," he said. But that comes with some responsibility. "If you want to be able to keep enjoying this natural spectacle... We need to take care of birds, we need to create cities that are a welcoming place for them."

- Emily Chung

Reader feedback

In last week's issue, we shone a light on the carbon footprint of ridesharing companies. Keith Rasmussen said, "Thanks for reminding us that Uber and Lyft are huge contributors to city pollution. And can we please stop referring to companies like Uber and Lyft as rideSHARING. There is no sharing about it, they are no different than a limousine or taxi company in what they do."

Responding to Emily Chung's piece on organized cleanup initiatives, Catharine Ross wrote, "I am appalled that there still have to be special events planned for cleaning up people's trash. This problem has to be addressed at the base level. Teach your children to never throw their garbage on the ground. Teach them respect for their habitat. Find a garbage barrel or take it home with you. Who among us doesn't realize that it's a bad thing? I can't understand the mindset of just throwing your garbage any old place. Never have, never will. Come on, people! This is the only world we have!"
There's also a radio show! Make sure to listen to on Sunday at 12:30 p.m., 1 p.m. in Newfoundland. You can also subscribe to What on Earth on Apple Podcasts, Google Play or wherever you get your podcasts. You can also listen anytime on .
The Big Picture: Arctic sea ice loss

Each year around this time, sea ice in the Arctic reaches its annual minimum, which is an opportunity to measure the longer-term trend of ice in the region. The Arctic helps regulate the climate of the entire planet, and the decreasing amount of September sea ice is a worrying sign of climate change. According to satellite data from NASA and the National Snow and Ice Data Center in the U.S., the amount of September Arctic sea ice in 1979 was above seven million square kilometres; in September 2019, it was around 4.5 million. The numbers suggest the ice is declining at a rate of nearly 13 per cent per decade.

Hot and bothered: Provocative ideas from around the web

Is the climate crisis more likely to be solved through greater personal responsibility (read: more conscientious consumption) or by regulating the biggest polluting industries? In terms of the most impact, it's undoubtedly the latter, and that requires voting for governments that care about such things. But this smart essay in the Atlantic suggests that by living more sustainably, individual people can actually begin to change broader opinions about the importance of the environment.

There's been a lot of talk in recent years about species extinction, but a new study says that nearly 50 bird and mammal species have recently been saved.

Google has said it achieved carbon-neutrality in 2007, but the company recently announced that through the purchase of offsets, it has now erased its entire carbon footprint.

The physical and emotional toll of far-off wildfires

Raging wildfires in the western United States smothered parts of B.C. with some of the dirtiest air on the planet this week, turning blue skies grey and at times an orangey brown.

Smoke has also drifted into Alberta and even eastern Canada, making its way to the Atlantic.

Liana Zwick said the smoke blanketing her small community of Castlegar, B.C., has been tough to take over the past few days. Her husband, who has a lung condition, has been unable to leave the house for his usual exercise routines.

Zwick said even for those with healthy respiratory systems, it is hard to be outside for any length of time. After adjusting to so many COVID-19 restrictions, she said reducing activities even further because of the smoke is hard to bear.

"The adjustments ... play havoc with your mind, and it's harder to stay upbeat," she said. "I think it's just that vicious circle: if it's not your physical health, then the anxiety."

For months, public health officials have been advising Canadians to get outside for their mental and physical health during the COVID-19 pandemic. Suddenly, that advice has come up hard against the realities of climate change.

Michael Brauer, a professor in the University of British Columbia's School of Population and Public Health, said smoke irritates the respiratory system, causing inflammation and breathing difficulties, which can lead to headaches, sore throat and coughing.

For those most at risk, including the elderly or those with underlying health conditions, it can bring on chest pain, shortness of breath, dizziness and heart palpitations.

Brauer said we need to get used to the idea that our air will be increasingly dirty and smoky in the coming years, as the planet continues to warm. "I'm not a climate modeller, but it's quite clear that it's going to get worse," he said.

Brauer said it's up to individuals, institutions and communities to look for ways to prepare for smoky skies during summer and autumn. For institutions, that means putting in plans and protocols - including the opening of "clean air shelters," such as the one Vancouver just opened for those who don't have access to indoor spaces with good air quality.

For individuals, it means managing health conditions properly, being prepared with medications before fire season begins and considering portable air cleaners, for those who have the means.

Beyond the physical health toll of smoky air, there's a psychological impact as well. Ashlee Cunsolo, dean of the School of Arctic and Sub-Arctic Studies at Memorial University, said environmental catastrophes provoke a spectrum of emotional responses, even when they're experienced from a distance.

"You might not be at the front lines of the wildfires and might not be in that acute emergency situation. But you certainly are still affected when you see the smoke," she said.

The smoke, she said, is a reminder of other people's suffering. "People talk about it as vicarious anxiety or anticipatory anxiety or concern," Cunsolo said. "And I think it's a function of human empathy."

Cunsolo suggested it's vital to develop emotional strategies to cope with environmental issues. Those might include talking with family and friends, getting more exercise, counselling or group therapy and doing things that make you feel like you're contributing positively to the world.

She said people should accept that the emotions they feel under oppressive and smoky skies are natural - and might even be helpful.

"The emotions that we feel in response to these things are opportunities or gifts that we're given to examine why we're feeling that way, and to examine what we value."

Task force calls on Ottawa to spend billions on 'green recovery'

An independent task force made up of experts in financial and environmental policy is calling on Ottawa to spend $55 billion over five years on clean energy and measures to cope with climate change to kick-start a Canadian economy stalled by the global pandemic.

A large portion of that sum - $27.25 billion - should be spent on retrofitting existing buildings to make them more energy-efficient and safer from the effects of climate change, according to the final report of the Task Force for a Resilient Recovery, released this week.

The group said the investment would boost the country's largest private sector industry by creating construction jobs, helping taxpayers cut their energy bills and also tackling the 13 per cent portion of Canada's carbon emissions that comes from buildings.

"That's where you get the most jobs with the least amount of public investment," said Bruce Lourie, task force member and president of the Ivey Foundation, a Toronto-based organization that promotes sustainable development.

The task force came together in May, and its 14 members include some former top political advisers - including Gerald Butts, ex-principal secretary to the prime minister, as well as former advisers to B.C. Premier John Horgan and Ontario Premier Doug Ford.

Its proposals also include new investments in clean energy, such as hydrogen, and increased production and promotion of zero-emission vehicles.

Lourie said many of the report's ideas are "so straightforward" he can't see why the federal government wouldn't adopt them.

At a two-day Liberal cabinet retreat this week, Environment Minister Jonathan Wilkinson said that while Canadians are "looking to us" to build "resilience" against the impacts of climate change, the government's "primary focus is on ensuring that we're supporting Canadians through this pandemic."

The task force is making the argument that restarting the economy and a green recovery are not mutually exclusive.

"In Canada, whenever people hear 'green,' they think it's some marginal little thing that environmentalists talk about," said Lourie. "But the reality is the world is moving to clean energy. The world is moving to electric vehicles and Canada is falling behind.

"In this country, we have to get over this divisiveness and the idea that somehow climate change is some airy-fairy idea out there, when really it's core to our future competitiveness."

The report also points out that other countries, notably in Europe, have already moved forward in announcing recovery plans with a green focus.

France, for example, has promised to use a third of its $155 billion Cdn recovery package on "greening the economy" - and critics are lamenting that amount is not enough. The European Union has pledged the largest-ever sum to tackle climate change: a whopping $855 billion Cdn over seven years.

Another task force member, longtime investment banker and sustainable finance expert Andy Chisholm - who the Liberal government appointed to a 2018 sustainable finance panel - told CBC News the Liberals have already signalled they will need to inject large amounts of stimulus cash into the economy.

Canada needs measures that "put us on a path for job recovery that is more sustainable over time because it plays into where the world is going," Chisholm said.

"If you're going to spend an enormous amount of money on stimulus going forward, then you should be trying to solve future issues and build long-term competitiveness and sustainability into your economy, so that you have the greatest impact and longest-lasting impact, rather than simply trying to restore the situation to what it was a year ago, while the world is moving on."

Deputy Prime Minister and Finance Minister Chrystia Freeland said Tuesday that while the ongoing fight against the pandemic remains the federal government's top priority, any recovery plan will contain green elements.

"I also spoke about the absolute priority that we place on jobs and growth and green jobs are absolutely going to be a part of our recovery," she said.

- Salimah Shivji

Stay in touch!

Are there issues you'd like us to cover? Questions you want answered? Do you just want to share a kind word? We'd love to hear from you. Email us at whatonearth@cbc.ca.

Sign up hereto get What on Earth? in your inbox every Thursday.

Editor: Andre Mayer | Logo design: Sködt McNalty

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Why birds migrate through cities - and how you can help them succeed | CBC News

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Hello, Earthlings! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.)

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Newsletter #2

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Hello, Earthlings! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.) This week:

Reducing light pollution has numerous benefits for the environment

The future of natural gas in the U.S.

Why poppies sprouted on Europe's battlefields

Reducing light pollution has numerous benefits for the environment

Typically, when people think about pollution, it's a question of air quality. But there's another kind that poses a threat to humans and animals: light pollution.

Multiple studies have shown that the abundant nighttime light found on streets and in buildings can adversely affect animals - altering migration patterns - as well as insects. There's also been increasing evidence that it can disrupt the circadian rhythm of humans, an important biological process that regulates our sleep cycle.

For these reasons, many people have advocated finding ways to reduce light pollution. But it's not always clear which sources are creating the most light.

A recent study published in the journal Lighting Research & Technology examined streetlights in Tucson, Ariz., over a period of 10 days. The city dimmed the lights at 1:30 a.m. every day during that period. Using satellites to monitor the light that seeped upward into space, the study found that light pollution dropped by just 13 per cent, suggesting that there are other sources of light that are causing pollution. (They suspect it could be things like billboards, car dealerships and parking lots.)

The importance of the study is to illustrate that cities can conduct similar research to determine ways to reduce light pollution from sources other than streetlights, said Christopher Kyba, a scientist with the GFZ German Research Center for Geosciences in Potsdam, Germany, and lead author of the paper. Kyba acknowledges more research is needed to determine exactly where that excess light pollution comes from, something that he hopes to examine in another study.

Finding out more about this could help cities design strategies to address the issue. But there's another benefit to reducing light pollution: less light means less energy production.

"All the light that we have is paid for by someone, and basically at the end of the day, it's us," said Kyba.

"We need the energy to produce all that light," he said, which could mean building environmentally unfriendly structures like a nuclear power plant or a hydro dam. "Or you have to burn coal or something and we all know that's bad for all kinds of reasons."

Kyba said, "anything we can do to reduce energy consumption is basically alleviating this other problem associated with energy production."

Robert Dick, former chair of the light pollution abatement committee at the Royal Astronomical Society of Canada, said light pollution should concern everyone.

"[People] should care about light pollution the same way they should care about reducing environmental pollution and designing cities to be sustainable," he said.

"Light pollution is one of those extra stressors you put on the environment."

- Nicole Mortillaro
(Full disclosure: Nicole Mortillaro is the editor of the Journal of the Royal Astronomical Society of Canada and the former head of the Toronto chapter of the International Dark-Sky Association.)
Reader feedback

In response to Yvette Brend's story on the Federal Court's dismissal of a youth-led climate change lawsuit against the government, Kathy Kilburn had this to say:

"The Federal Court's refusal to hear the young people's lawsuit is another brick in the wall of denial, obfuscation and bureaucratic drivel that is helping to doom our planet and its passengers," wrote Kilburn. "Disgusting. Keep slugging, kids - this old foop is behind you! My generation should have done SO much better."

Old issues of What on Earth? are right here.
There's also a radio show! Tune in to What On Earth this week for a look at the push to develop small modular reactors as Ottawa seeks to achieve net-zero emissions. But opinions are divided, and some warn SMRs are a dangerous distraction from real climate action. What on Earth airs Sunday at 12:30 p.m., 1 p.m. in Newfoundland, and is available any time on podcast or CBC Listen.
The Big Picture: The future of natural gas in the U.S.

In a push to energize indecisive voters in swing state Pennsylvania during the final weeks of the U.S. election campaign, President Donald Trump warned that Democratic candidate Joe Biden would ban fracking (hydraulic fracturing), which has provided a lot of jobs to the region. Biden vigorously denied he would do any such thing. Setting aside the fact that the process of fracking to extract gas has become increasingly unpalatable to Pennsylvanians, recent analysis shows that gas is losing its hold on energy generation in the U.S. Once touted as a "bridge" fuel in the transition to a low-carbon economy, natural gas is fighting a losing battle against renewable energy sources like wind, solar and geothermal. A recent analysis by the investment firm Morgan Stanley projected that by 2028, renewable energy will overtake natural gas in U.S. power generation (as measured in gigawatt hours).

Hot and bothered: Provocative ideas from around the web

The New York Times has a well-earned reputation for producing compelling interactive features. This one on Alberta's abandoned oil wells is no different. It's premised on this chilling fact: The nearly 100,000 inactive wells "are unlikely to be switched on ever again but have not yet been decommissioned. No one knows how many are leaking methane and other pollutants."

Not only is Glasgow preparing to host the COP26 climate summit next year, but Scotland is close to reaching a lofty goal of generating 100 per cent of its power from renewable energy, primarily wind. Some people have even taken to calling Scotland "the Saudi Arabia of renewables."

Australia could soon be home to a 10-gigawatt solar farm spanning 12,000 hectares. Not only would that make it the biggest in the world, but two-thirds of the power is set to be exported to Singapore - 4,500 kilometres away - via "high-voltage direct current undersea cable."

Why poppies sprouted on Europe's battlefields

As Remembrance Day approaches, many of us will be pinning a poppy to our jacket or lapel.

The red flower became a symbol of remembrance because it sprouted over the battlefields of Europe after the First World War. John McRae's well-known 1915 poem In Flanders Fields describes poppies growing between the crosses of fallen soldiers.

But of all plants, why were poppies the first to grow there? And why did they grow in such abundance? Turns out it's a case of environmental renewal.

"A poppy is one of those pioneer, ruderal plants," said Egan Davis, principal instructor for the horticulture training program at the University of British Columbia's Botanical Garden. "Their role is to basically patch [a] site after major disturbance."

That could be a natural disaster, like a flood or forest fire, or, in the case of European battlefields, ongoing fighting that wiped out most trees and vegetation.
- Menaka Raman-Wilms
"The seeds are there, waiting," Davis said. He referred to it as a "seed bank" - seeds lying dormant in the soil, ready to germinate. When the disaster has passed and all other plants have been wiped out, those seeds have the space to grow.

"What's really beautiful about that system is that at any point, where there's a big disturbance and everything crashes, it just basically kickstarts," Davis said.

Poppies play the role of that common first plant in parts of Europe. Davis said that in much of Canada, fireweed is the first to sprout after forest fires.

Those pioneer plants that grow after a disaster are "usually the most glorious," he said. "That's what their role is: basically flower like crazy."

He said that once the poppies come up, bigger plants and shrubs will start to return to rebuild the natural habitat of the area. With this in mind, Davis said he sees the poppy as a sign of renewal.

"I can't imagine anything more disturbing to the earth and to human society than war," he said. "But when poppies germinate after the war, that's a sign of promise."

Stay in touch!

Are there issues you'd like us to cover? Questions you want answered? Do you just want to share a kind word? We'd love to hear from you. Email us at whatonearth@cbc.ca.

Sign up hereto get What on Earth? in your inbox every Thursday.

Editor: Andre Mayer | Logo design: Sködt McNalty

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Reducing light pollution has numerous benefits for the environment | CBC News

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Hello, Earthlings! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.) This week: Reducing light pollution has numerous benefits for the environment The future of natural gas in the U.S.

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  This Is A Problem!!!! Birds Migrating Thought Cities

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  This Is A Problem!!!! Birds Migrating Thought Cities

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Birds fly though cities for a few reasons: the follow lakes and rivers which are located close to human settlements and they travel at night and follow the stars but city lights also look like stars. The problem is that due to these lights looking like stars birds crash into windows causing death. Birds causing into windows is the second reason why birds die due to humans other is house cats. It is causing a lowering of the bird populations which could lead to the extinction to some birds.

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We found this article on light pollution's affects on bird's migration interesting because it pairs well with our main newsletter article and light pollution is higher during their migration and other times. To find out more read the article 😉

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Introduction

Migratory bird species perform seasonal movements between stationary breeding and non-breeding grounds twice every year. While some species migrate during the day (e.g., raptors, aerial insectivores), many others do so at night (e.g., most songbirds, waterfowl and shorebirds). For all of these species, migration may be the most challenging stage of the annual cycle for survival as conditions encountered en route are often unfamiliar and unpredictable1,2. Nocturnal migrants, in particular, are faced with light pollution, an anthropogenic hazard that has increased rapidly in the last few decades. Light pollution is caused by artificial light at night (ALAN) deployed to illuminate human dwellings but spilling over and spreading into the airspace, reaching areas not inhabited by humans3 in the form of skyglow (scatter of light due to particles suspended in the atmosphere). Since the invention of the electrical light-bulb in the 19 th century, the use of ALAN and the associated light pollution has increased so dramatically that more than one third of the human population is no longer able to see the Milky Way4.

Light pollution has effects on humans and wildlife. Beyond ruining the romantic pastime of stargazing for humans, ALAN has been linked to important physiological and epidemiological maladies such as cancer incidence5 and reduced skeletal muscle function6. Effects of ALAN on wildlife have been recorded as well7. Recent examples include influences on nest site selection by sea turtles8, changes in the diversity and behavior of nocturnal moths9, and alterations to ecological interactions of insects10. Trees in close proximity to sources of artificial lights budburst earlier than trees away from lights11. In birds, a positive phototaxis effect (attraction to lights) has been known for a long time12. Two of the best documented effects of light pollution on birds is the high mortality due to collision with illuminated buildings and windows13,14, and the stranding of seabirds which commonly get drawn by light sources to land15. More subtle effects of light pollution on birds are also known, such as disorientation16, alterations in reproductive physiology17,18, disruption of circadian rhythms19,20, and changes of flight behavior21,22. Considering the large encroachment of light pollution worldwide4 and its known effects on birds, our objective was to test the association of the amount of light pollution (i.e. mean ALAN intensity) within the geographic ranges of nocturnally-migrating birds among five factors including phase of annual cycle, mean distance between breeding and non-breeding ranges, range size, global hemisphere of range, and status of species conservation concern. We were particularly interested in determining if ALAN was relatively greater within the exclusive passage ranges of bird species during migration compared to their distribution ranges during other phases of the annual cycle after controlling for other confounding factors associated with ALAN.

Despite the widespread use of ALAN, most of the world's oceans and large water bodies, as well as regions of land at extreme latitudes and within the sub-tropical and tropical latitudes within South America, most of Africa, and most of interior Australia remain largely free of light pollution (Fig. 1). Boreal and tropical regions, where many species of nocturnal migrant birds breed and spend the non-breeding season respectively, have a lower proportion of their land surface permeated by light pollution compared to temperate ecosystems23. Hence, we predicted that higher levels of light pollution occur (1) within passage ranges that birds traverse during migration relative to stationary breeding and non-breeding ranges. We assumed that long distance migrants traverse more areas subject to light pollution, and that species with broader distributions incorporate more urban areas, hence we also predicted higher levels of light pollution (2) for species with longer migration distances, and (3) for species with larger geographic ranges. Furthermore, the known adverse effects of light pollution on birds (e.g. mortality due to collision with lit structures, or association with habitat loss from urban development) led us to hypothesize that (4) higher levels of light pollution would be related to species of higher conservation concern. Identifying when during the annual cycle, and whether susceptible species face higher levels of light pollution will aid in directing research efforts to evaluate effects of light pollution in these highly mobile organisms.

Worldwide distribution of artificial light at night (ALAN - yellow areas over black background). Lines connect centroids of wintering and breeding ranges of nocturnally-migrating bird species considered for analysis (n = 298). Line color represents distances shorter (white) or longer (grey) than the overall median distance. Shorter distances overlap areas with high concentration of ALAN, mainly in North America and eastern Asia. ALAN corresponds to the "vcm-orm-ntl" product (cloud and ephemeral lights free, background set to zero) from the 2015 VIIRS nighttime lights annual composite produced by the Earth Observation Group, NOAA National Geophysical Data Center62,63. Map was created with ArcMap version 10.466 ( http://desktop.arcgis.com/en/arcmap/).

Results

We considered 298 species for analysis, 179 in the western and 119 in the eastern hemisphere (see Methods and Supplementary Table S1). The geographic distribution ranges of nearly all species contained some degree of light pollution during all phases of the annual cycle; the only exception was the migration range of the Golden Crowned Sparrow ( Zonotrichia atricapilla). The families with the most species used for analysis were Parulidae (Wood warblers, 41 spp.), Anatidae (Waterfowl, 32 spp.), and Scolopacidae (Shorebirds, 32 spp.). The species with the greatest mean light pollution were the Basra reed warbler ( Acrocephalus griseldis) in its breeding range, and the Sakhalin leaf warbler ( Phylloscopus borealoides) in both its migration and non-breeding ranges. The full dataset is provided in Supplementary Table S2.

The Boosted Regression Tree (BRT) model indicated moderately weak associations among factors with ALAN intensity within geographic ranges (20% of the total deviance explained). Seasonal range size was the most important variable associated with the amount of light pollution, followed by migration distance, phase of annual cycle, and hemisphere (Fig. 2). Consistent with our prediction, we found a higher amount of light pollution in passage ranges compared to stationary ranges. The intensity of light pollution was significantly different between breeding and migration (z = 4.90, n = 897, p < 0.001), and non-breeding and migration ranges (z = −4.16, n = 897, p < 0.001), but not between breeding and non-breeding ranges (z = 0.73, n = 897, p = 0.741) when assessed with Generalized Linear Models. Contrary to our expectations, however, we found lesser mean light pollution for species with longer migration distances and larger seasonal ranges. A strong interaction between range size and migration distance revealed that light pollution varies more widely with migration distance for species with relatively small ranges than for species with relatively large ranges (Fig. 3). Short distance migrants tend to spend their full annual cycle within the bright temperate regions of North America and eastern Asia (Fig. 1) and occupy ranges with higher levels of light pollution than long-distance migrants. We also found that the geographic ranges of species in the Western hemisphere had relatively higher levels of light pollution than those in the Eastern hemisphere. Finally, the association of light pollution with status of conservation concern was extremely weak.

Partial dependence plots of variables associated with intensity of light pollution in the geographic ranges of 298 nocturnally-migrating bird species. Y-axes show the marginal intensity of ALAN in units of 1E9*nanoWatts*cm −2*sr −1; notice different scales among plots. Rug plots shown inside the top two main plots on the x-axis show deciles of the distribution of predictor values. Values in parenthesis of X-axis label indicate the relative influence of each predictor variable.

Partial dependence plot for the interactions of seasonal range area and migration distance on the mean artificial lights at night (ALAN) within the geographic ranges of 298 nocturnally-migrating bird species around the world.

We inspected the worldwide distribution of the 298 species considered for analysis, and found that the highest species richness occurs in the Western hemisphere (Fig. 4). The highly light-polluted areas in Central and Eastern US hold the highest species richness of migration ranges in the world, while the highest species richness of breeding ranges occur in boreal forests of Canada, and the highest species richness of non-breeding ranges occur in Mexico, along its Pacific and Gulf of Mexico coastlines.

Species richness in ( a) breeding, ( b) migration, and ( c) non-breeding ranges for 298 nocturnally-migrating bird species, estimated by intersecting geographic range map polygons for each phase of annual cycle. This map was created in R version 3.3.270 ( https://cran.r-project.org/) with geospatial data from the Birds of the World Geodatabase64, and edited with ArcMap version 10.466 ( http://desktop.arcgis.com/en/arcmap/).

Discussion

Light pollution was relatively greater within the exclusive passage ranges of nocturnally-migrating bird species during migration compared to their distribution ranges during other phases of the annual cycle after controlling for other factors associated with ALAN. The largest concentrations of ALAN generally occur in urban areas, which occupy about 0.5% of the global land surface, and are mostly concentrated between 30°N and 45°N latitude24. Many species of nocturnal migrants breed in boreal forests north of 50° latitude, for example north of the US-Canada border25, and winter in tropical areas south of Tropic of Cancer (25°N Latitude). Hence, during migration, long distance migrants traverse latitudes with the highest urban development in the world, leaving from and arriving to areas with low levels of light pollution. Although some land bird species breeding in the Southern Hemisphere migrate to northern latitudes during winter time, bird migration is mainly a Northern hemisphere phenomenon, with most species of migratory land birds moving from North to South between breeding and non-breeding areas respectively26. Thus, it appears that many long distance migratory birds are exposed to more extensive ALAN in areas they traverse while aloft during migration, a period of great selective pressure when birds must repeatedly locate stopover habitats where they can safely rest and refuel and contend with weather to fly long distances to reach their destinations in a timely manner. Migration is also the time of year when the ecological impacts of ALAN on the behavior and survival of birds have been well studied27. Therefore, we focus our discussion on the impacts of ALAN on birds during migration.

Although ALAN has a small cumulative spatial footprint on the globe, the worldwide distribution of human settlements produces some degree of light pollution within the geographic ranges of all species of nocturnally migrating birds, as it does for mammals28 and ecosystems23 around the world. Light pollution is present in every continent4 except perhaps Antarctica. However, human settlements and artificially-lit-structures are not evenly distributed around the globe4. Accordingly, we found the amount of light pollution within migratory bird ranges varied with migration distance, range size, and global hemisphere. These associations were important confounds to control for when assessing the relative association of ALAN among ranges for different phases of the annual cycle. However, they present some interesting patterns in their own right. Short distance migrants may be associated with greater light pollution because they tend to occur within temperate regions where urban development is most widespread. Likewise, since intensity of sky brightness fades with distance from the source29,30, species with relatively larger ranges and longer migration distances encompass regions with less human development and have ranges with relatively lower levels of light pollution. Birds migrating through the Nearctic-Neotropical migratory system, in the western hemisphere, move through the US, one of the most urbanized countries in the world24, and concentrate during their non-breeding stage in the less urbanized but still light-polluted region formed by Mexico, Central America, and the northern portion of South America4. Geographic ranges of bird species in the eastern hemisphere overlap the heavily urbanized and highly light-polluted European Union4, but also over Africa and Oceania, the regions in the world with the lowest urbanized fraction24, and hence with low encroachment of light pollution. Central and northern Asia, also part of the eastern hemisphere, seem relatively free of light pollution4.

At a fine scale, negative consequences have been demonstrated for birds during nocturnal migratory flight. Point sources of ALAN disorient and attract birds actively engaged in migration27,31,32,33,34 to the extent that birds can be "trapped" by bright sources of ALAN when migrating over urban areas. High-intensity urban light installations can dramatically alter multiple behaviors of nocturnally migrating birds even to distances of several kilometers from the source35. Migrants will slow down their flight speed, start circling the light source, and call more frequently near the lights. It is well known that bird mortality due to collisions with buildings is related to light emissions from the buildings13,14, but some species appear more susceptible to collision than others36,37, suggesting that light pollution has a species-specific effect among nocturnal migrants.

The influence of ALAN on migratory birds also reaches beyond the extent of urban areas. Artificial lights can be perceived from beyond the point sources, particularly during overcast nights38. For example, the skyglow of large metropolitan areas may be perceived by an observer at the Earth's surface from up to 320 kilometers away39. Birds aloft will perceive skyglow from even farther away depending on their flight height. Previous research has shown that migrating birds orient towards the skyglow of urban areas, particularly juveniles40. Consistent with this behavior, McLaren et al.41 discovered that total nocturnal migrant bird stopover density on the ground increases monotonically with proximity to areas with bright skyglow over a range of distance up to 200 km. Despite this broad-scale attraction to urban areas, presumably during migratory flight, birds avoid using bright areas at a small scale (1 km radius) for stopping over. Others have found urban sources of ALAN are associated with higher levels of migrant stopover abundance both within green spaces at the interior of urban areas and along urban boundaries42,43,44, supporting the conclusion that observed associations with urban environments during migration45,46 are driven, at least in part, by broad-scale attraction to urban sources of ALAN. In contrast, areas containing high levels of ALAN are generally avoided by migratory birds during the breeding and non-breeding seasons42,46. Thus, urban sources of ALAN broadly effect migratory behavior and may have a role in shaping migratory routes of individual species, emphasizing the need to better understand the implications of ALAN for migratory bird populations.

Despite the growing body of evidence about the negative effects of light pollution on the environment, the total surface of the planet exposed to light pollution and the brightness of ALAN has increased in recent years47. Thus, a call has been made to integrate light pollution in global change research48. Continued research on the impact of light pollution on migrating birds at different scales is needed. Future efforts should include continuing to evaluate the influence of ALAN in selection of stopover sites, utilization of green spaces in urban areas, and altering flight behavior. New insights are also needed into the differential effects of ground-based lights as compared to lights in tall structures, and the influence of ALAN in altering the selection of migratory routes, overall migration success, and the onset of migration. For example, light pollution disrupts the timing of bird activities49,50,51, including sleep cycles19,52. A combination of methods could provide further insight about the extent and impact of light pollution on migratory birds. Local measures of light pollution could be obtained with light meters53 or digital cameras38 in stopover sites remotely identified with weather radars43,54. Light-level loggers have been used to measure the intensity of light to which birds are exposed in urban and rural environments (reviewed in55). This approach could be adapted to provide insight into the levels of ALAN in the stopover sites used by migrating birds. Additionally, increasing day length is related to initiation of developmental stages for spring migration in different bird species (e.g. fattening, hypertrophy of flight muscles, and expression of metabolic enzymes and hormones; reviewed in56). Extended periods of activity into the night by birds near urban areas49 suggest that some birds may be experiencing increased periods with exposure to light50, which has been proven to affect hormone levels and gonadal development18. While actual departure for migration depends on factors other than photoperiod57, light pollution may alter the onset of migration, particularly for species with small geographic ranges that include urban areas.

Methods

Artificial light at night

We mosaicked six geotiff tiles from the Earth Observation Group (EOG) at NOAA National Geophysical Data Center to create a complete dataset of ALAN for the entire world. Each tile contains the mean annual radiance composited from nighttime images taken by the Suomi National Polar-orbiting Partnership (NPP) satellite with its Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) during 2015, and are produced in 15 arc-second resolution grids. Although monthly composites are available, we preferred to use annual composites because it prevents the results from being confounded by seasonal variations of snow and vegetation cover58,59. The full mosaic spans the globe from 75 N latitude to 65 S. Descriptions of the capabilities of the DNB sensor are available in60,61. We used the "vcm-orm-ntl" set of products, which are cloud-free, have had fires (gas flares included) and other ephemeral lights removed, and the background has been set to zero (e.g. moonlight reflection from the earth), leaving just sources of consistent ALAN primarily from electric lighting sources62. See62 for a full account of the production process of the composited nighttime image used for analysis, and for the complete details of the type of light sources excluded from the dataset. Radiance is measured in units of nanoWatts per square centimeter per steradian (nW cm ² sr) but have been multiplied by 1E963. Original radiance values in the individual tiles ranged from −0.12712 to 97386.8. We log ₁₀-transformed these values to improve its distribution for analysis, adding 1 first to retain all values. The log-transformed values range from −0.059 to 4.988. We converted the polygon geographic ranges of each species (see below) in each phase of annual cycle to raster grids of the same resolution of the ALAN data before calculating the geometric mean of ALAN (i.e. mean of the log ₁₀-transformed intensity).

Geographic ranges of birds

We used the Birds of the World geodatabase (BOTW)64 to obtain geospatial data characterizing the presence, origin and seasonality of 10,423 bird species around the world. We defined migratory species as those with a distinct "passage" geographic range ("known or thought very likely to occur regularly during a relatively short period(s) of the year on migration between breeding and non-breeding ranges"65), and filtered out diurnal migrants. For analyses, we only used data of nocturnal migrants with breeding, migration, and non-breeding ranges identified in the BOTW as extant and native. We cataloged 388 bird species as nocturnal migrants. We examined species with worldwide distribution, and from those with presence in both hemispheres we used data from the hemisphere containing breeding, migration, and non-breeding ranges. We excluded species with migration ranges that sparingly connect breeding and non-breeding ranges (i.e., don't include most of the land area that migrants fly over during migration). We considered 298 species for analyses. We split the ranges for Nelson's sparrow ( Ammodramus nelsoni) into two migratory populations. Thus, we used 299 geographic ranges for each phase of the annual cycle.

Predictor variables

We classified the geographic ranges of nocturnally migrating species by hemisphere (western: migratory species in the Nearctic-Neotropical system; eastern: all other species). We projected the geographic ranges to the Mollweide equal-area projection in ArcMap 10.466 where we used the "Calculate geometry" tool to estimate the area of seasonal geographic ranges in km ². We defined and estimated migration distances as the great circle distance in kilometers between the centroid of each species breeding and non-breeding ranges. We obtained the category of conservation concern for each species from the International Union for Conservation of Nature (IUCN) Red List API67. We used the eBird/Clements checklist of birds of the world68 to obtain taxonomic Families and current scientific names (scientific names from the BOTW database are not current).

Analysis

We used the gradient boosting method of Boosted Regression Trees (BRT) to model the variability of mean ALAN for each species of nocturnal migrant (n = 298), with five predictor variables: migration distance (log km), area of geographic range (log km ²), phase of annual cycle, hemisphere, and IUCN category of conservation concern. BRT does not make assumptions about the data distribution of the response variable, hence it can fit non-linear response functions; in addition, it automatically models interactions among predictors, and can therefore perform better than Generalized Linear Models (GLM) and Generalized Additive Models (GAM)69. BRT analysis was performed in R70 with the library 'dismo' and function 'gbm.step', which optimizes the fit of the model through cross validation71. We used a tree complexity of 2 to allow two-way interactions among predictors, bag fraction of 0.5, a Gaussian error distribution, and a learning rate of 0.001 to produce a minimum of 1000 trees in the optimized model. The learning rate weighted the contribution of each tree to the model, and the bag fraction specified the proportion of data used to train the model69. We compared the mean intensity of light pollution between phases of the annual cycle with a multiple comparison of means (Tukey) post-hoc analysis, after a Generalized Linear Model (GLM) was fitted to our data with the same five predictors as with the BRT. We quantified the worldwide distribution of species richness by overlapping the geographic ranges of the 298 species included in the modeling analyses.

Data availability

All data generated or analyzed during this study are included in the Supplementary Information files.

Change history

14 March 2018

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

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Acknowledgements

S.A.C.C. was supported by Fulbright-García Robles and CONACyT scholarships during the project. Financial support also provided by the University of Delaware. We thank two anonymous reviewers who helped improve the manuscript.

Author information

Affiliations

Department of Entomology and Wildlife Ecology, University of Delaware, Newark, 19716, USA

Sergio A. Cabrera-Cruz, Jaclyn A. Smolinsky & Jeffrey J. Buler

Contributions

S.A.C.C. conceived the study, collected, processed and analyzed the data, and wrote the first draft of this paper. J.J.B. provided supplies and input during analysis of data. J.A.S. processed data. All authors reviewed and contributed to the last version of this manuscript.

Corresponding author

Correspondence to Sergio A. Cabrera-Cruz.

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Cabrera-Cruz, S.A., Smolinsky, J.A. & Buler, J.J. Light pollution is greatest within migration passage areas for nocturnally-migrating birds around the world. Sci Rep 8, 3261 (2018). https://doi.org/10.1038/s41598-018-21577-6
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Light pollution is greatest within migration passage areas for nocturnally-migrating birds around the world

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Excessive or misdirected artificial light at night (ALAN) produces light pollution that influences several aspects of the biology and ecology of birds, including disruption of circadian rhythms and disorientation during flight. Many migrating birds traverse large expanses of land twice every year at night when ALAN illuminates the sky.

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We found this article on 9/11 light memorial pulling in huge flocks of birds and though it was interesting because just how birds are attracted to bright lights and how it effects there migration. We'll won't spoil anymore of the awesome article. Hope you enjoy😁

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A striking memorial art installation that lights up the night sky in New York City every Sept. 11 temporarily messes with the migrations of hundreds of thousands of songbirds each year.

The Tribute in Light creates two blazing columns of light where the twin towers of the World Trade Center once stood. The iconic towers were destroyed after being struck by hijacked passenger planes on Sept. 11, 2001, killing 2,753 people.

There's almost this magnetic pull of birds to these lights. - Kyle Horton, Cornell Lab of Ornithology

The memorial is powered by 88 powerful spotlights whose beams reach six kilometres into the sky and can be viewed from as far as 100 kilometres away. It's lit from dusk to dawn - though not always continuously - every Sept. 11 in memory of those who died in the attacks.

But mid-September is often when many songbirds make the long, exhausting flight from their breeding grounds, largely in Canada's boreal forests, to their winter homes in the southern U.S., Mexico, and Central and South America.

They fly mostly at night, and because they've evolved to navigate with the help of the stars, they're attracted to artificial light. Such lights can lead them to collide with buildings and other human-built structures; it's the second leading cause of bird deaths in North America after cats.

Extreme lights

The Tribute in Light is an extreme example of such lights - but birds are irresistibly attracted to the bright memorial.

Video recorded on Sept. 11, 2010, shows a flurry of what look like hundreds of insects circling aimlessly through the light beams. But they're birds, mostly warblers, said Kyle Horton, who witnessed the phenomenon first-hand last year.

"There's this sound element to this as well, of thousands of birds calling ... and it sounds like an insect chorus," said Horton, a postdoctoral researcher at the Cornell Lab of Ornithology in Ithaca, N.Y.

Birds make that type of call when they're disoriented, he said.

Horton and colleagues in the U.S. and the U.K. measured the effect using radar - the kind used to track storms and other weather - and published the results in a study last fall. Horton also spoke about the study at the North American Congress for Conservation Biology in Toronto this past summer.

"Using the radar data is quite remarkable - to actually quantify it - because the scope of the attraction is beyond what we visually can see," said Horton in an interview following his talk.

There were typically about 500 birds within half a kilometre of the Tribute in Light memorial when it wasn't lit, Horton found. But within 20 minutes of the beams switching on, the number of birds skyrocketed to nearly 16,000.

"There's almost this magnetic pull of birds to these lights," he said.

Temporary respite

Horton and his colleagues estimate 1.1 million migrating birds were affected by the Tribute in Light in a seven-year period between 2008 and 2016.

That's despite the fact that since 2009, the lights are shut off for 20 minutes whenever volunteers count more than 1,000 birds in the beams - under an agreement between the local conservation group New York City Audubon and the National September 11 Memorial and Museum, which runs the installation.

"The worst-case scenario is that there are birds that collide with buildings, or the light directly results in the mortality of birds," Horton said.

The researchers think that's relatively rare. But even if the birds aren't killed directly, the lights can still have a negative impact, Horton said.

"There's no doubt that the birds are expending unnecessary energy by circling and calling in these lights," he said. That's at a time when the migrating birds need to save some energy for the thousands of kilometres they have left to fly.

Shutting the lights off temporarily appears to allow the birds to find their bearings and continue southward. And Horton said it's encouraging that the people of New York City are willing to temporarily douse the lights for the birds.

Michael Mesure, executive director and co-founder of FLAP Canada, a Toronto-based group that aims to reduce bird collisions with human-built structures, agrees that's great.

"But the fact is that we shouldn't be attracting them in the first place," he said.

FLAP worked with the New York City Audubon to try to convince New York authorities not to build the light monument, Mesure said, but the groups were unsuccessful.

CN Tower lessons

FLAP had anticipated a problem after previous experiences with migrating birds at structures like the CN Tower, which used to be lit up by intense floodlights.

After FLAP showed that it was drawing in hundreds of birds each spring and fall, the CN Tower agreed to shut off the lights during migration season. "The problem virtually disappeared at that particular structure," Mesure said.

The CN Tower's floodlights have since been replaced by dimmer, colour-changing LEDs that don't attract birds in the same way.

Mesure thinks more could be done to minimize the impact of the Tribute in Light.

"I get it, it's an anniversary date," he said. "But find either another way to celebrate or have that tribute at a different time of year to avoid this issue from happening."

On the other hand, both Mesure and Horton say the Tribute in Light is only a small contribution to the much bigger problem of urban lights on migrating birds.

Horton's radar research also shows birds fly disproportionately through cities.

It's not just because they're attracted to the lights, Mesure says, but also because many of North America's biggest cities are located in traditional migration corridors, and along lakes and other shorelines that birds use for navigation.

That means cities need to do their best to reduce the impact of artificial lights on migrating birds, he said.

Some, such as Toronto, have started doing that by incorporating bird-friendly design standards for new buildings that:

Discourage "vanity lighting" that spotlights building facades by pointing upward.

Encourage the use of motion-activated, instead of "always on," lighting.

Require lighting over pathways to be directional, so it only points at what needs to be lit, instead of everywhere.

"Any light at night at the wrong place, at the wrong time can be lethal to a bird," Mesure said.

But bird deaths are highly preventable, he added.

"You'll never find a problem as easy as this - you flip a switch and the problem disappears."

# data[].attributes.attachment_link.title
9/11 light memorial pulls in huge flocks of migrating birds | CBC News

# data[].attributes.attachment_link.description
A striking memorial art installation that lights up the night sky in New York City every Sept. 11 temporarily messes with the migrations of hundreds of thousands of songbirds each year. The Tribute in Light creates two blazing columns of light where the twin towers of the World Trade Center once stood.

# data[].attributes.headline
This Is One Solution For Birds Migrating Through Cities That We Could All Do!

# data[].attributes.subject
This Is One Solution For Birds Migrating Through Cities That We Could All Do!

# data[].attributes.body
We can all close our curtains or reduce the amount of lighting we use at night.  This would be a simple and easy solution for when birds migrate so they don't get off track of their migration journey by following the city lights.

# data[].attributes.headline
This Is One Solution For Birds Migrating Through Cities That Sounds Interesting That Just Might Work!

# data[].attributes.subject
This Is One Solution For Birds Migrating Through Cities That Sounds Interesting That Just Might Work!

# data[].attributes.body
An interesting solution is that we can all get to know the birds that fly through our cities/towns. This would allow us to know what they need to survive and put them in less harm.

# data[].attributes.headline
This Is One Solution For Birds Migrating Through Cities That Sounds Crazy!

# data[].attributes.subject
This Is One Solution For Birds Migrating Through Cities That Sounds Crazy!

# data[].attributes.body
A crazy solution for birds migrating through cities is reducing the size of your lawn and letting part of it grow.  This would increase the number of insects which means there'd be more food for the birds.