Harrowsmith Fall 2019 | 215can’t see what’s outdoors,
anyway. If you appreciate the
sounds and the solitude of the
night, do your part to preserve it.
Finally, don’t use white light
outdoors at night, as it blinds
our night vision. It also fools the
circadian rhythms of all life
into perceiving it as daylight.
For humans, the resulting ill
health may be a nuisance, but
for animals it’s a matter of life
and death.
Have you wondered how
animals navigate at night?
During our late-evening
walkabouts, we navigate by
landmarks and perhaps even
by starlight if we are travelling
across unfamiliar territory.
So do animals. But our society
promotes only the use of our
daytime vision with an urban
policy requiring illumination
that is so bright our night vision
is blinded. Once blinded, it takes
several minutes of darkness for
it to recover. We are able to wait,
but this delay makes animals
vulnerable to predation.
The anonymity provided by
darkness keeps more timid
creatures safe as they forage
for food. In the bush, animals
can use their memory of paths
and scents. In open grassland
with few landmarks, they can
use the stars. But exposure to a
bright light makes the landscape
and the sky look black and
featureless.
Animals use their circadian
rhythm to compensate for
the shift in the star’s position
as Earth rotates, so they can
navigate back to the safety of
their borrows before dawn.
But our artificial lights create
“stationary stars” on the horizon.
At the end of the night, these
“stars” give a false direction,
trapping the animals in the
open at dawn and making them
vulnerable to predation.
Animals are smart: they don’t
want to go where they cannot see.
Without their night vision, they
can only see the bright patches
of light, not the landscape. The
predators, however, like light—it
helps them hunt. Artificial light
gives the predator the advantage.
A predator is only a nuisance
for the homeowner but deadly
for its prey. HThe anonymity provided by darkness keeps more
timid creatures safe as they forage for food. In the bush,
animals can use their memory of paths and scents. In
open grassland with few landmarks, they can use the
stars. But exposure to a bright light makes the landscape
and the sky look black and featureless.ENVIRONMENT: LIGHT POLLUTION