Todd McLeish: Artificial light threatens animal populations
Light pollution is mostly unpolarized, and its addition to moonlight results in a decreased polarization signal.
From ecoRI News (ecori.org)
Global insect populations have declined by as much as 75 percent during the past 50 years, according to scientists, potentially leading to catastrophic impacts on wildlife, the environment and human health. Most studies point to habitat loss, climate change, industrial farming and pesticide use as the main factors driving the loss of insects, but a new study in the United Kingdom points to another cause: light pollution.
The ever-increasing glow of artificial light from street lights, especially LED lights, was found to have detrimental effects on the behavior of moths, resulting in a reduction in caterpillar numbers by half. And since birds and other wildlife rely on caterpillars as an important food source, the consequences of this decline could be devastating.
According to Douglas Boyes of the British Center for Ecology & Hydrology, street lights cause nocturnal moths to postpone laying their eggs while also making the insects more visible to predators such as bats. In addition, caterpillars that hatch near artificial light exhibit abnormal feeding behavior.
But moths are not the only wildlife affected by artificial light.
Since most songbirds migrate at night, birds that have evolved to use the moon and stars as navigational tools during migration often become disoriented when flying over a landscape illuminated with artificial light.
“City centers that are very bright at night can act as attractants to migrating birds,” said ornithologist Charles Clarkson, director of avian research at the Audubon Society of Rhode Island. “They get pulled toward cities, and when they find themselves amid heavily lit buildings, they become disoriented, leading to a large number of window strikes and increased mortality.”
It is unclear why birds are attracted to lights, but studies have found increasing densities of migrating birds the closer one gets to cities.
“Birds probably see these cities on the horizon from a long distance, and they get pulled toward these locations en masse,” Clarkson said.
Street lights have also been found to be problematic to birds. Birds are active later into the evening when they are exposed to nearby artificial lighting at night, and they often sing later as well.
“Sometimes that might lead to more food availability, since lights attract insects,” Clarkson said. “But it also affects the physiology of the birds when they’re active when they should be sleeping. Some birds that live in heavily lit urban or suburban areas begin nesting earlier, too, up to a month earlier than they typically would. And that leads to a phenological mismatch between when food is traditionally available and when the chicks are hatching and need to be fed.”
Artificial lighting may cause other species to face a similar mismatch. Christopher Thawley, a lecturer and researcher in the Department of Biological Sciences at the University of Rhode Island, studied lizards in Florida and found not only that the reptiles advanced the onset of breeding when exposed to artificial light, but they also laid more eggs and even grew larger under artificial lighting conditions. Other kinds of wildlife could have comparable results.
“Light at night can sometimes mimic a longer day length, and a lot of animals use length of day as a cue for when to start breeding,” he said. “If they’re exposed to light at night, they think the days are longer so it must be time to breed. Length of daylight is also a good cue for when to migrate or when to start calling, and that could potentially be an issue for some species.”
Thawley said frogs that call at night near artificial light could be more vulnerable to predators.
“When nights are darker, frogs call more, and when the moon is bright they call less,” he said. “It’s more dangerous to call during a full moon because predators could see you. That would be especially true under artificial lighting conditions, too.”
Scientists are still trying to understand the intricacies of how light pollution impacts wildlife, and yet some cities are already taking action to reduce its impact. Dozens of cities around the United States and Canada, including Boston, New York, Chicago and Washington, D.C., have launched “lights out” programs aimed at dimming city lights during the peak of bird migration.
Providence is not among the cities participating in a “lights out” program, but local advocates have discussed how to get it started for several years. They say it would be a positive first step toward reducing the impact of artificial lighting on local and migrating wildlife.
Rhode Island resident and author Todd McLeish runs a wildlife blog and frequently writes for ecoRI News.
Grace Kelly: Light pollution hurts a wide range of animals, including humans
From ecoRI News (ecori.org)
You might not think much about the light on your porch, or the cute lanterns that line the pathway up to your door. But shining a little illumination on the situation of light pollution reveals that it can have a bigger impact than you might think.
“The spread of electric lighting in particular has provided a major perturbation to natural light regimes, and in consequence arguably a rather novel environmental pressure, disrupting natural cycles of light and darkness,” according to a 2013 report.
Bright city lights distract and disorient migratory birds, often causing them to collide with tall buildings. It’s estimated that about 985 million birds are killed this way annually in the United States alone.
Beyond birds, light pollution is also affecting insects, according to a recent study titled Light pollution is a driver of insect declines.
“We strongly believe artificial light at night — in combination with habitat loss, chemical pollution, invasive species, and climate change — is driving insect declines,” the scientist authors concluded after assessing more than 150 studies. “We posit here that artificial light at night is another important — but often overlooked — bringer of the insect apocalypse.”
Artificial light can hinder insect courtship and mating, and car lights lead to hundreds of billions of insect deaths each year in Germany alone.
In Rhode Island and much of the rest of New Eng the story is no different.
“Pretty much all of the Northeast is super light-saturated and has huge amounts of light pollution,” said Kim Calcagno, Audubon Society of Rhode Island’s manager of the Powder Mill Ledges Wildlife Refuge, in Smithfield, R.I., and the Florence Sutherland Fort & Richard Knight Fort Nature Refuge in North Smithfield, R.I.. “And with the main refuge that I manage at our headquarters in Smithfield, I can’t even do most night hikes anymore because there’s so much light pollution, and if affects the wildlife so much that it’s just not worth it, because we don’t hear or see anything a lot of the time.”
Beyond disorienting birds or indirectly causing their death, light pollution can also impact Rhode Island’s migratory bird flyways.
In a 2017 ecoRI News article, ornithologist Charles Clarkson, who worked with the Rhode Island Department of Environmental Management to collect local bird-migration data, said, “We’ve confirmed what we’ve always suspected: Rhode Island is a very important stopover site for migrants.”
Birds migrating north along the Atlantic Flyway travel west of Rhode Island, while those that travel south in the fall cross through the state. Light pollution can disrupt these paths, confusing birds and causing them to miss vital stops along their migration.
“Birds that migrate, songbirds especially, usually migrate at night,” Calcagno said. “So light pollution can disorient them, can cause them to hit buildings, and it can cause them to be attracted to certain lighting. We have resorts and hotels and all these things along the coast which can affect them. It can cause a lot of birds to not go the way they’re supposed to go; or it can increase mortality from strikes; or they may even fly too far over the ocean to get away from the light, get exhausted and fall out of the sky and not survive.”
One essential stop on many a migratory bird’s journey is the Ninigret Pond and Conservation Areas in Charlestown, R.I., a town that prides itself on land preservation, lack of development, and its lighting ordinance.
“Charlestown has a lot of open space — about 46 percent of the town is preserved in some form or another,” said Ruth Platner, a longtime member of the Charlestown Planning Commission. “Ninigret wildlife refuge is really important for bird migrations because it’s one of the first places that has food and provides rest. The refuge itself is dark, but then the areas around it, we'd like them to stay dark, too.”
Enacted in 2012, the town’s Dark Sky Lighting ordinance provides rules for light use and installation, ranging from rules relegating lights in outdoor activity areas to sign illumination.
“It’s only for commercial use. We wanted to do it for everything, but at the time, the council approved it for commercial,” Platner said. “So, for new constructions and adding new fixtures, they have to be full cutoff fixtures, which means the light is fully within the figure. All the light should be going down and not out, and definitely not up.”
Southern New England isn’t all that dark at night. (NASA)
Human health impacts
Light pollution can also disturb the very people illuminating the world at night.
Nighttime lighting “is associated with reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, impaired daytime functioning, and obesity,” according to the American Medical Association.
“My friend who is astronomer had a neighbor who had a super-bright spotlight, and the spotlight was shining into her house, like so much so that his light was invading her interior space even after she bought blackout curtains,” said Kimberly Arcand, a science communicator and the visualization and emerging technology lead for NASA’s Chandra X-ray Observatory. “It can affect your mental health if you've got a bright spotlight shining into your living room every night.”
Her friend, Tracy Prell, an executive board member of Skyscrapers Inc., the Amateur Astronomical Society of Rhode Island, has been battling the light pollution around her East Providence townhouse for years.
“When I first moved here, I didn’t think anything of it, but then I was outside and my neighbors turned on their floodlights,” she said. “A couple times one had left them on overnight. She turns the outside light on because she has to let her dog out, and I’m thinking, do animals really need that much light to see? Two hundred watts? Her light illuminates my living room.”
Prell has asked for her neighbors to point the lights downward or to get a shield, but it has been hard to convince them to reduce their light pollution — unless saving money is mentioned. While she has found resistance, she hopes that through education, people will be inspired to make a change.
Arcand, who is also a Rhode Island resident, feels similarly, and has long been passionate about light pollution, primarily because it’s a problem that anyone can take action to reduce.
“I think one of the reasons I like light pollution so much as a topic is because as an individual … there are accessible, actionable things that you can do to reduce light pollution in your home,” she said.
Such actions include installing motion-sensor lights in your yard, angling outdoor lights in a certain way to reduce glare, using warm color LEDs, or simply turning off your lights when you’re not using them. You can even go beyond your personal impact and take action to reduce light pollution in your community.
“If you're at all interested in going beyond personal responsibilities, there are a number of committees created or in existence to work on changing the lighting in a given town,” Arcand said. “Guiding town decisions in a way that reduces light pollution while also reducing energy use and still keeping things safely lit, it’s just a win-win.”
Grace Kelly is a reporter with ecoRI News.