Dark Skies advocates make the case for dimming city lights

SCIENCE by Gregory Beatty

What if I told you there was a way we could (1) improve human health (2) reduce taxes and utility rates (3) cut back on pollution and (4) protect wildlife habitat for plants and animals? It would seem like a no-brainer, right?

All we have to do is take an inventory of our existing nighttime lighting and determine, first, if the light is necessary; and if it is, ask if it’s properly designed to minimize what Dark Skies advocates call “light trespass”.

After all, it’s not like humans are built for round-the-clock light.

Think back a few hundred years. Outside of torches, hearth and campfires, and primitive lanterns, we, like other life on Earth, existed in a day/night cycle governed by the rising and setting Sun.

Now, our urban environments in particular are awash in light 24/7.

And it’s messing with our health, says Maureen Luchsinger.

“All living things have an internal biological clock that regulates their activity during the day/night cycle,” says Luchsinger, the education coordinator at the Ann and Sandy Cross Conservation Area near Calgary.

“It impacts on the production of melatonin, which is a hormone that helps regulate the ebb and flow of other hormones. It’s necessary for humans, animals and plants to repair damaged tissues and support their immune systems to fight infections,” she says.

Circadian rhythm is the technical term for that cycle, and all sorts of animal behaviours are influenced by it — from hunting and foraging to mating and migration.

And just as we’re being adversely affected by our love affair with light, plants and animals are struggling too.

Nocturnal Habitat

On Aug. 21, Luchsinger’s colleague at the conservation area, Laura Griffin, presents a webinar reviewing some of those impacts and steps we can take to help our fellow creatures.

“We’re located just outside Calgary city limits,” says Griffin. “Even in this rural setting we’re still impacted by the effects of light pollution. Sky glow, for instance, can be seen from many kilometres away. It can light up an area, and disorientate some animals.

“The meadow lark, for example, typically starts to do its mating songs at sunrise. There’s been documented cases where it starts to sing around 2 a.m. because it’s seen skyglow and been confused and thinks this is the time it can attract a mate when that’s not the case.”

Frogs are similarly affected, says Griffin.

“The males do their mating calls [at night], and one impact of light pollution is they are less likely to call when they’re around artificial light. So if they’re less likely to call, then females are less likely to find them.”

Breeding isn’t the only nocturnal activity animals engage in. For many, it’s when they venture out of their burrows, nests and dens to hunt and forage.

“It’s known that the Ord’s kangaroo rat, because it has lots of predators, will avoid moonlit nights to forage,” says Griffin. “Artificial light from industrial areas will light up the sky enough that it doesn’t want to go out, which has a big impact on a little rat because they don’t even drink water. They get all their water from the food they eat, so if they can’t forage for food for fear of being eaten they’re not going to get hydrated.”

The Ord’s kangaroo rat, by the way, is classed as endangered. Light pollution isn’t the sole cause of that, obviously, but in the wild the balance between life and death is always fine, and any intrusion that tilts the odds one way or the other can have a profound effect.

Studies show bats are also being affected, says Griffin.

“To forage and hunt at night bats use eco-location, so they’re well-adapted to the night-time environment,” she says. “One European study showed that the introduction of street lights into an area caused the disappearance of a bat species. They suspect it was out-competed by another bat species that was more light tolerant and able to take advantage of insects that were being attracted to the light.”

Migration is another behaviour that can be adversely impacted by light pollution. By flying at night, birds avoid predators such as hawks and eagles, while also benefiting from greater lift from the generally cooler and denser air. It also frees them up to land during the day to feed and rest, while keeping a watchful eye out for air and land-based predators.

But too much light interferes with all that.

“Migrating birds have difficulty coping with light pollution because they use star patterns to guide them,” says Luchsinger. “We would also like to see corporations look at how they light their buildings and other properties, such as car dealerships, at night. Birds are drawn to the light, and fly around it until they drop from exhaustion.”

Intrusive light isn’t the only way we’re hurting nocturnal animals. The noise we generate through our industry and transportation, entertainment and other activities can also be harmful.

“Different animals have different adaptations to be able to survive in the nocturnal world,” Griffin says. “Bats have their echolocation; the Ord’s kangaroo rat has a tympanic bone that allows them to sense vibration — so the operation of machinery in wilderness areas will cause them to change their foraging habits.”

Owls rely heavily on sound to find prey when hunting at night too. Some species even have specially aligned ears that allow them hone in on their prey’s location.

But in a noisy environment, they lose that natural advantage.

Trees, Shrubs & More

Like animals, plants also exist within the day/night cycle. That’s true both day-to-day and also season-to-season, where the waxing and waning of the Sun gives them cues on the optimum time to bloom, bud and produce seeds, as well as prepare for winter dormancy.

The waning daylight in the fall, says Luchsinger, initiates a biochemical change in plants.

“The leaves start to die off, they change colour,” Luchsinger says. “This process allows all the nutrients to go back into the growing and storage organ. That helps create a healthy plant in the future.

“If there’s artificial light around, the plants lose the ability to put nutrients back in the root system,” she adds. “Then if there’s a frost, they could die off. It also makes them more susceptible to fungal infections and insect infestations.

“So an unobstructed dark period is critical to their ability to survive.”

Taxes & Utilities

We use light at night for lots of reasons. Some are legit, such as safety and security. Other uses, like advertising and promotion on big/bright signs, video billboards and floodlights, are more dubious. I mean, come on — does anyone need brilliantly-lit street signs flashing ads for politicians, used cars and country concerts at three in the morning? No. No they do not.

Regardless of the reason, we need to be smart in how we use light at night, says Griffin.

“There’s this myth that the more light you have the safer you are. But if it’s creating glare, then there’s dark shadows where you can’t see. Similarly, if the light’s on all night, you’re not necessarily going to notice when someone comes into your yard — whereas if you have a motion-sensor, that actually provides a more effective alert.”

Proper light design doesn’t just reduce light trespass, says Luchsinger — it enhances the efficiency of the light we do use.

“If you have the right fixture that directs light where you want it to go, you can use lower wattage bulbs. The colour of light is also important — blue/white light is less desirable than yellow/amber which is less disruptive for animals including humans.”

Each step we take will save money for cash-strapped governments and beleaguered home and business owners through reduced utility and health costs — while simultaneously reducing our environmental footprint.

Then there’s astronomers. For obvious reasons, they’re big advocates of Dark Skies — and they can be effective allies for conservation groups, says Luchsinger.

“Education is the greatest tool we have to help people understand,” says Luchsinger. “A lot of people don’t even know there’s nocturnal life around us, but it’s really important to increase awareness and appreciation of the nocturnal environment for all species — and develop conservation strategies not just outside the city but within urban areas.”

It’s time for city planners, businesses and home owners to think about darker nights. With so many benefits, it’s only a matter of time before the lightbulb goes on and everyone gets it. ❧

Sign up for the Aug. 21 webinar at pcap-sk.org and see darksky.org for more on Dark Skies.