by Nancy Lawson

Plants, animals and other organisms all
feel the harmful effects of artificial
lighting, and the cumulative consequences
can be dire. Read on for a few simple
ways to embrace the darkness—and help
these creatures—in your own yard. Photo by Zffoto/

On summer evenings, my husband
and I head to the darkest spot of our
property to look for the light—in the form
of fireflies rising from meadow grasses
and twinkling their way into the trees.

As the tulip poplars behind this
spectacular display settle in for slumber,
white yucca flowers open their petals,
beckoning tiny moths. Yellow common
evening primroses say hello to the moon,
exposing ultraviolet patterns that guide
pollinators to their nectar. Bats swoop in
to sample the menu while owls hoot and
cackle across the canopy.

The vibrant nightlife is a treat we look
forward to all year. It might also become
increasingly rare in a world where artificial
lights shine brighter, longer and more
ubiquitously. As scientists explore links
between the quest for eternal sunshine
and human health hazards, from sleep
disorders to cancer, they’re also naming
light pollution as a significant but largely
hidden contributor to habitat loss.
Mounting evidence points to “pervasive,
long-term stress on ecosystems,” the journal Nature reported in January, “from
coasts to farmland to urban waterways.”

The volume of research spans the
natural world, chronicling disruption in
life cycles of animals, plants and other
organisms. Most well-known among the
casualties are baby turtles, who head
for illuminated hotels instead of the
moonlit sea, and migrating birds thrown
off course by spotlights shining into the
sky. But artificial lighting also causes
salamanders to sleep later, songbirds to
sing earlier, moths to stop mating, bats
to avoid drinking, plants to reduce flowering,
trees to hold onto their leaves and
even zooplankton to cease rising to lake
surfaces to eat algae.

The cumulative effects are far-reaching, negatively influencing everything
from reproduction to predator/prey
relationships. And though it may at first
seem surprising that even trees need to
catch some z’s, darkness is part of most
species’ survival. Aside from those who
dwell deep in oceans, soil or caves, “every
creature on this planet has evolved in
bright days and dark nights,” writes Paul
Bogard in The End of Night. “None has
had the evolutionary time to adapt to the
blitzkrieg of artificial light.”

TAKE ACTION: Get a Humane Backyard sign to help get others interested in gardening for wildlife.

Compounding the problem is a rebound
effect of cheaper lighting. Hailed
as eco-friendly because of their energy
efficiency, LEDs cost so much less than
previous technologies that artificially lit
outdoor areas have actually expanded, at
a rate of 2.2 percent annually worldwide.
Many new fixtures incorporate large
amounts of the blue light that’s particularly
disruptive to circadian rhythms,
spelling even more trouble for the
30 percent of vertebrates and 60 percent
of invertebrates who are nocturnal.

If there’s any hope, it’s that light
pollution is reversible with the flick of
many switches. In that respect, “it’s not
like climate change or toxins in the
environment,” says Bogard. “It’s serious,
and it’s a big problem, but it’s one we
could solve.”

Though commercial and public
properties are the biggest light polluters,
the estimated 1 billion light fixtures surrounding
U.S. homes are significant contributors.
A few practical steps can bring
back the night to our garden habitats.

  • Attracted to outdoor bulbs, giant silk moths waste energy
    circling the lights instead of mating and laying eggs. Photo by Steven Ellingson/

Go dark

Though shielded lights
mitigate astronomical light pollution,
their downcast glow still affects life
below. A recent Illinois study found
that high-pressure sodium lighting from
nearby roadways delayed maturation of
soybean plants, while a Swiss study
showed that LED street lamps reduced
insect visits by 62 percent, resulting in
lower fruit production. Diminish such
effects by turning off outdoor lights
when not in use.

Install motion-sensing lights

Glare can limit night vision
and obscure visibility. Motion-detecting
lighting is safer, says Pete Strasser of
the International Dark-Sky Association,
brightening your own path when needed
and warning trespassers.

Choose bulbs wisely

Not all
organisms react the same way to the
same spectrum. After a specially developed
light kept migrating songbirds from
landing on North Sea oil platforms, it
was tried in Hawaii to help threatened
seabirds confused by brightly lit resorts,
says Strasser: “And they were attracted
to it. So there’s no single wildlifefriendly
spectrum. It can be all over
the map.” In a home setting, try warm
LEDs; they may attract fewer insects
than other lighting.

Close your curtains; open your mind

Turn off interior lights when not
in use and close blinds at twilight. But
don’t shut out the world entirely. Step
outside to greet the night, and you just
might find some magic. Last summer,
on a seaside walk in nearby Delaware,
blue-green stars sparkled at our feet—
the bioluminescent dinoflagellates that
tourists travel long distances to see. By
adjusting our eyes, our mindsets and,
most of all, our lighting, we can observe
such wonders all around us, often in our
own backyard.

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Article source: HSUS

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