A few hours north of Portland, dark-sky advocates are pushing to rebrand Maine as a destination for astrotourists, hoping that the largest stretch of light pollution-free sky in the Eastern United States, spanning Acadia to Katahdin, could attract tourists – and locals, too.

But there are dark-sky enthusiasts whose vested interest lies even closer to home. We’re talking about critters such as birds, bats and insects that live in your own backyard, outdoor dwellers who rely on darkness to migrate, forage, mate and hibernate.

The streetlights, exterior home and business lights, gas station lights, stadium lights and parking lot lights that dot our neighborhoods and let humans extend our daylight activities can imperil the lives of these animals. They already face any number of other serious threats, such as climate change, habitat loss and collisions with cars. As Greater Portland’s population grows and human Mainers encroach more and more on animals’ habits and habitats, the impact of man-made lighting grows alongside.

Each species is affected differently, but generally speaking, light pollution disrupts circadian rhythms and what wildlife biologists call “time portioning,” meaning when animals do specific activities.

“As we continue to see suburban sprawl reaching into historically dark areas, we should expect to see lower productivity and higher mortality in many of our native species,” said Doug Hitchcox, staff naturalist at Maine Audubon.

Streetlights and other types of exterior lighting allow humans to extend daylight activities, but biologists warn of consequences to critters. Artificial light disrupts circadian rhythms and “time portioning” – when animals do specific activities – and some species become more vulnerable to predation.

Hitchcox and his colleague, Maine Audubon conservation biologist Sarah Haggerty, specified some of the effects:

• Some animals mistake artificial lights for moonlight.

• Some are disoriented by artificial lights.

• Man-made lights automatically favor diurnal species, and can lead to conflicts between them and their nocturnal counterparts.

• The problem of predation also disproportionately hurts nocturnal species, which have evolved to hide. Exposed to lights, they are more likely to get eaten.

• When man-made light extends the day into night, nocturnal mammals – among them beavers, bats and most rodents – have less time (and surface area) to scavenge for food.

• “Many mammals will catch food and then carry it to a dark, safe place before eating, so light pollution will cause them to spend more time seeking out these safe areas,” Hitchcox said.

Solar-powered walkway lights soak up sunlight during the day.

Haggerty spelled out the problems for several particular creatures. The clam worm spawns in the light of the full moon, she said. But in shorelit areas (such as much of developed coastal Maine), man-made lights block out the moon, impeding the clams’ timing. Several amphibian species rely on the secretion of melatonin in their metamorphoses from tadpole to adult; the increase of artificial light may slow their development. And perhaps most familiar to the layperson – the moth. A moth flitting around a light is a moth that is not doing its job, Haggerty said. And because moths comprise a large chunk of pollinating insects, when lights disrupt their pollination tasks, the whole ecosystem suffers.

Airborne creatures such as moths, fireflies and birds bear the brunt of the impact of man-made lights, said Hitchcox, who specializes in ornithology. Nine-hundred million birds die each year over the United States during migrations, he said. Most of the deaths occur among songbirds, such as warblers. These smaller birds like to travel at night in order to avoid large predators, such as hawks, eagles and falcons, which migrate during the day. And while Maine-specific migratory bird studies are rare, Hitchcox says artificial light carries some of the blame.

He’s collected some of his own anecdotal evidence: On Portland’s West End, where he lives, Hitchcox has noticed an uptick of birds that swoop into lower altitudes during fall migration on the nights that Hadlock Field turns on its stadium lights. The lights may be attracting them, or disorienting them – scientists aren’t sure. In either case, it’s bad news for the birds, as these migrating birds are safer at higher altitudes, where they are less likely to collide with tall buildings.

“The tough thing is that no one really cares about this because no one knows it’s happening,” he said. “My goal is to get at least a baseline to show people that, ‘Hey, there are thousands of birds flying overhead at night. Could you please turn those lights off a little earlier?’ ”

The International Dark-Sky Association has not yet decided whether to recognize Maine’s starry skies as an IDA-recognized site. But you can take steps to reduce the impact of artificial light on Maine’s wildlife right now. We phoned local and national experts to compile a how-to guide to reducing light pollution around your home and neighborhood.

Some of their advice may seem obvious, some of it may surprise you. We’re not asking you to return to the age of candles; fighting light pollution doesn’t mean sacrificing lighting. Read on for tips on how to cut down on light pollution and help our ecosystems thrive.

Use the porch light when you need to – then shut it off.

SHOP SMART

What should you look for when you are buying exterior lights? Opt for lights with no more than 3000 kelvins; the higher the kelvins, the brighter the light. Also, lower kelvin lights give off a softer orange and yellow glow. The International Dark-Sky Association (IDA) has teamed up with retailers like Home Depot and Volt to provide IDA-approved bulbs. Look for their seal on light packaging or visit darksky.org to see where you can buy lights locally. Companies like Starry Night Lights offer an array of night-sky friendly bulbs.

Replace bright lights with low-wattage or solar-powered walkway lighting. Core Glow stones are a popular pick. This eco-friendly pebble lighting is electricity-free and photoluminescent, meaning that each stone collects daylight in order to give off an ambient glow at night. Core Glow stones also serve as light pollution indicators: if the glow is bright and vibrant, the light pollution in your area is not a problem; if stones are faint or not visible, you’ve still got some work to do.

When you’re installing your new lights, make sure that individual bulbs are angled downward and shielded so they don’t project light into the sky.

SWITCH IT OFF

“The most important tip is to use what is necessary, and the amount necessary, and no more,” dark-sky advocate and film director Sriram Murali said.

Yes, one of the most cost-effective and easiest ways to reduce your personal contribution to light pollution is to turn the lights off when you’re no longer using them. We can’t even believe we have to tell you this.

Must your porch light really stay on all night? Couldn’t it go off at 11 p.m., say?

If you’re anxious for your safety, consider installing motion-sensor lights and timers. “If you think about it,” Murali said, “What’s more startling to a thief? A light that’s on all night, or one that turns on all of a sudden?”

Also, really bright lights don’t necessarily make you safer, because, counterintuitively, they can make it harder to see, according to Nancy Hathaway, a Surry-based dark-sky advocate. Just picture driving at night and being blinded by another driver’s high beams.

INSTALL A SMART SYSTEM

Make your life even easier. Buy a system that will remember to turn off the lights for you. What is the backdrop of a Ray Bradburian dystopia for some is a sustainable paradise for others – especially when you’re just a one-click app away from seamless control of all your home appliances. With smart grid systems, you can manage household and business energy consumption, even when you’re away from home. Such systems let you control your outdoor light emissions from season to season, as the days grow longer and shorter.

Draw curtains and close blinds to prevent indoor light leakage.

SHIELD INDOOR LIGHTS

Though outdoor lights are, by far, the greatest cause of light pollution, be aware of indoor light leakage, too. Draw your curtains and close your blinds at night. This is even more important during spring and fall bird migration (especially if you live in a city with high-rise buildings). Small actions like these are easy to do and build the foundations of a cleaner sky – in your neighborhood and in Maine. Though it’s sometimes hard to imagine small actions making much of an impact, consider the moths: Those that cluster at your window are missing out on pollinating a wealth of plants. Multiply that by an entire region and you’ve got some seriously disrupted ecosystems.

PERSUADE YOUR FRIENDS

People know about plastic pollution. They know about car emissions. They know about trash. But do most people ever think about light pollution? Help increase awareness. Provide neighbors, family, and friends with information about light pollution: its causes, effects, and ways to address the problem.

Do you have a neighbor who leaves glaring outdoor lights on all night long? Hathaway recommends a two-pronged approach: kindness coupled with education.

“A few years ago, on a new moon evening when the sky was dark and starry, I went outside to view the stars,” Hathaway said. “Shining into my eyes was my neighbor’s garage light shining right onto my porch. I dialed his number, and made my request, ‘I am outside looking at the stars and wondered if you would be willing to turn your garage light off?’ ‘Of course!’ was the reply. His light has never been on since.”

Hathaway also recommends hosting star parties for your community, where attendees can view the night sky through telescopes with educated astronomers. “Education and bringing some mindfulness into a request seems to work well.”

BE AN ENGAGED CITIZEN

In 2018, the City of Portland embarked on a streetlight conversion and smart city project, which entails replacing old street lights with new lights that are better for the environment: they are angled down, use less energy and allow city staff to control the light output of each fixture. South Portland is now doing the same. Read up on the IDA and Illuminating Engineering Society of North America’s Model Lighting Ordinance and see what your city can and is doing to regulate light pollution. The IDA offers tips for implementing a lighting ordinance in your city. You can also advocate for more environmentally friendly city lighting with your local representative or by writing a letter to your city council.

A pedestrian at the corner of Moulton and Fore streets in Portland. This year the city embarked on a program to replace old streetlights with ones that use less energy.

Reach out to local businesses to ask them to avoid light clutter, a term used for an excessive grouping of lighting, such as bright billboards and highly illuminated establishments. If they take no action and you’re ready to take the hard line, tell them you plan to patronize more eco-friendly competitors until they step up their game.

SEE FOR YOURSELF

Visit a Dark Sky-approved site to take a gander at what you’re missing. Check out the closest Dark Sky Place to Portland, which is Mont-Megantic, a national park in Quebec, in Canada or visit the places in Maine that are vying for the designation, like Katahdin Woods and Waters National Monument or Acadia National Park. Bring your children, grandchildren, nieces, nephews or young friends to give them a chance to see an unadulterated night sky. Here’s hoping that the beauty of a truly dark night sky will encourage you to renew your commitment to minimizing light pollution and to really seeing that change through.

Surya Milner is a rising senior at Bowdoin College studying English. She can be reached at:

smilner@pressherald.com

Twitter: suryamilner