Life Nature Magazine

OPINION FROM DUSK UNTIL DAWN AUTUMN ISSUE
The fading night
Some years ago, while hitchhiking around the sparsely populated landscape of Namibia, I was camping in a remote location in
the north of the country. There was no moon that night, and leaving my tent to go to the toilet I was initially overwhelmed by the
incredible display of stars arching overhead, but also by a deep fear. It was so dark, with barely any discernable background glow on
the sky, that the only way to see where the horizon began was by the absence of stars. This was the deepest view of creation I’d ever
had, and yet it felt more claustrophobic than ever, as though the universe was on the verge of collapsing on itself. It was a profound
reminder of how adapted I am to the day, and how successfully we have banished the darkness of night from our experience in the
developed world.
Our remote ancestors in the Mesozoic
were well adapted to nocturnal life,
as many mammals and other animals
are today. The daily cycle of light and dark
are essential in regulating the circadian 24-
hour rhythms of most animals. Humans have
millennia, but over the past century there has
been an explosion of night illumination with
the advent of electric lighting.
the most overlooked factor in the complex
web of the causes of biodiversity decline.
to a reduction in visibility to predators. In a
natural environment these moonless nights
will be exploitable with each lunar cycle,
opportunities are lost. It’s apparent that
species in the shadows.
A brief look at a satellite image of the world
at night shows how seriously our densely
has seen serious declines in numerous animal
populations over the last few decades. Moths
last decade, and we are just beginning to
understand the extent to which the problem
factors, particularly habitat destruction,
in most population declines, but this is
something that would be so easy to address.
Aside from the obvious issue of wasted
energy, do we really need streetlights to be on
all night, especially on weeknights in rural
villages? It’s comforting for us, and it has
been argued that accidents and crime rates
are lower in areas that are brightly lit, but
Image: NASA, 2013.
of many animals, and there is evidence that
they disrupt the rhythms of birds, insects,
reptiles and numerous other nocturnal
animals. One of the best-studied examples is
that of turtle hatchlings on tropical beaches,
horizon inland. Under normal circumstances,
hatchlings instinctively orientate away from
the dark silhouette of the horizon towards
the brighter, starry sky, leading them to the
electric lights, the turtles often head inland,
away from the sea, where they can become
exhausted and disorientated, run over by
the extra illumination to their advantage.
Light pollution has been linked to population
declines in snakes, disruptions of migrating
birds and bats, amphibians, and invertebrates.
Research suggests that invertebrate activity
and small mammal distribution is increased
on darker, moonless nights, probably due
lights being brighter than stars even at large
distances, the insects become disorientated
and unable to navigate in the darker areas
night of moths around streetlamps saps the
animals’ energy, and creates an aggregation
of prey for nocturnal insectivorous predators
such as bats, which in turn are more
accidents. Moths escaping predation will often
land nearby, unable to navigate in the dark
surroundings, leading to a loss of opportunity
for feeding. This process has been referred
insects are drawn out of suitable habitats
for miles around the light source, leading
to depleted populations in the surrounding
countryside.
The reduction in moth populations may
also be a major factor in the current serious
are heavily dependent on moths as prey.
we need to spend more energy and money
understanding which lighting types have the
least ecological damage. Thankfully some
local authorities are rolling out testing periods
reducing the amount or type of lighting used,
but this is largely focused on money saving
rather than ecosystem regenerating.
quietest periods each night would give
wildlife a chance to disperse and resume
it’s normal rhythms of activity, and we
consumption, enjoying richer biodiversity,
and of course, re-acquainting ourselves with
the darkness which is as much a part of our
circadian rhythm as any other species.
Written by Feargus Cooney,
third year Conservation Biology
and Ecology BSc with the
University of Exeter, Cornwall
Campus.University of Exeter,
24