24 | New Scientist | 7 December 2019
O
NE of my cats has died,
and I am bereft. It wasn’t
the one we expected to
lose first, the saggy old ginger
tom, but the much younger one
who we thought had many years
left in him. Turns out he had a
weak heart. Mine is now broken.
I tell you this not to wallow in
grief but to raise an issue that
rarely gets an airing when we talk
about making personal sacrifices
to help the environment. I loved
my cat and I miss him, but I take
comfort from the fact that my
loss is the planet’s gain.
I have long suspected that my
cats are a major contributor to
my household’s environmental
footprint. Unlike the humans
who live there, they eat meat
every day. They also slaughter
wildlife. Though the one we lost
was a gentle soul, he was also a
ruthless killer. I have cleaned
up my fair share of decapitated
mice and shredded spiders, and
once watched, helpless and
aghast, as he killed a wren in
the back garden.
A few cans of cat food and the
odd mauled bird hardly constitute
ecocide, but summed across the
world, domestic cats are a serious
environmental menace. If you
doubt this – and I know I have
already raised some hackles –
I recommend a devastatingly
brilliant article called “The
ecological cost of pets” by biologist
Peter Marra of Georgetown
University and the Smithsonian
Conservation Biology Institute
in Washington DC.
Marra is a well-known critic of
cats. In 2016, he co-authored a book
called Cat Wars, which argued
that domestic moggies have a
devastating impact on wildlife.
His new article, published
in the journal Current Biology,
demolished my lingering hope
that the ecological impact ofmy cats is negligible. In the UK,
for example, pet cats kill more
than 275 million small animals a
year. In the US, the toll is probably
in the billions. This is just pet cats;
feral cats kill even more (both my
cats were strays before we took
them in).
This predation is ecologically
significant, says Marra. It has
already contributed to the
extinction of 63 species worldwide
and continues to threaten
hundreds more. In certain
circumstances even a lone cat can
do irreversible damage. In the late
19th century, for example, the
Stephens Island wren was single-pawedly wiped out by a lighthouse
keeper’s cat called Tibbles.
In my defence, most of
these actual and threatened
extinctions are in faraway places,
not gardens in London, and the
British species of wren isn’t
remotely endangered. But that
doesn’t absolve me. The mere
presence of a free-roaming cat
can instil fear and stress in birds,
causing nesting adults to
reduce their parenting and
even abandon nests.
Some of the birds I see in my
garden, including house sparrows
and starlings, are already in
serious decline due to human-
induced habitat loss. Cats are
an extra pressure they could
do without.
If any dog lovers are feeling
smug at this point, don’t. Dogs
also stress wildlife. One study
found that areas of woodland
frequented by dog walkersexperience a 35 to 40 per cent
reduction in bird diversity
and abundance.
Pet ownership also imposes
wider environmental costs. Added
together, all the cats and dogs in
the US consume the same amount
of energy as 60 million people,
effectively increasing the
population by a fifth.
Ingredients in pet food are
often leftovers from the human
food chain, but this isn’t always
the case. Even if they are, they still
have to be processed, packaged
and transported. What comes
out the other end is an even
stinkier problem, equivalent to
the faeces of 90 million people,
generating 64 million tonnes
of greenhouse gases.
Being an animal lover and
caring about the environment
often go hand in hand. But they
aren’t compatible. I hate to say it,
but pet ownership is another
unsustainable aspect of modern
consumer lifestyles that we are
going to have to confront. It isn’t
the biggest, but it isn’t negligible.
Like almost every other
environmental vice, the problem
is getting worse as pet ownership
rises around the world.
That isn’t to say that pet
ownership is totally indefensible.
Marra accepts that it can have
major psychological and physical
benefits, and so supports
“responsible ownership”. In the
case of cats, that means keeping
them indoors at all times, which
I don’t think is compatible with
their own physical and
psychological health.
I went meat free for
environmental reasons. I’m
working on going cheese free
and car free. Going cat free will be
10 times harder than any of these,
but when the saggy old ginger tom
succumbs to the inevitable, I will
try to make that the end of it. ❚This column will appear
monthly. Up next week:
Annalee Newitz“ In the late
19th century, the
Stephens Island
wren was wiped
out by a cat called
Tibbles”Your pet’s ecological footprint From domestic cats’ ecocide of
small animals to the greenhouse gases they emit, owning a pet is
an environmental vice we must confront, writes Graham LawtonNo planet B
What I’m reading
I’ve just picked up a copy
of Reef Life by coral
expert Callum Roberts.
Can’t wait to dive in.What I’m watching
The BBC adaptation of
His Dark Materials.
Brilliant, though Lyra’s
dæmon Pan is a painful
reminder of my late cat.What I’m working on
A story about restaurants
where the food is
prepared, cooked and
served by robots.Graham’s week
Graham Lawton is a staff
writer at New Scientist and
author of The Origin of (Almost)
Everything. You can follow him
@grahamlawtonViews Columnist