How to eradicate grey squirrels without firing a
shot – an astonishing tale of ecological
restoration.
By George Monbiot, published on the Guardian’s
website 20th January 2015
Is there anything more stupid than the government’s
plan to kill grey squirrels?
I ask not because I believe – as
Animal Aid does – that grey squirrels are
harmless. Far from it: they have eliminated red
squirrels from most of Britain since their
introduction by Victorian landowners, and are now
doing the same thing in parts of the Continent. By
destroying young trees, they also make the
establishment of new woodland almost impossible in
many places. As someone who believes there should be
many more trees in this country, I see that as a
problem. A big one.
No, I oppose the cull for two reasons. The first is
that it’s a total waste of time and money. Here’s
what scientists who have studied such programmes have
to say:
“To date, there has been no successful method
developed in the long-term control (nor indeed the
eradication) of grey squirrel populations. … a
recovery in numbers was found to take place within
10 weeks of intensive culling programs.”
You pour the money in and it pours out the other
side. The government’s plan to sponsor an
“eradication programme” to the tune of £100
per hectare per year is futile; though it will
have the effect of transferring even more public
money to rural landowners.
I doubt you’ll be surprised to hear that the idea
was approved by the former environment secretary
Owen Paterson, whose primary mission in office
appears to have been showering his chums with gold,
while ruthlessly cutting any spending that might
have delivered wider benefits. This was the man,
remember, who almost
doubled the subsidy for grouse moors.
My second reason for opposing the cull is that
there is another way of dealing with grey squirrels,
which requires hardly any expense, indeed hardly any
human intervention at all. Unlike trapping, shooting
or poisoning, it works. It is happening with extreme
prejudice in Ireland at the moment.
There is a scientific term for this method. Pine
martens.
Pine martens are predators native to Britain and
most of Europe. They are members of the otter,
badger and weasel family (the mustelids), that are
at home both on the ground and in the trees. They
are, to my eye, exceptionally beautiful. They look
like sinuous chestnut cats with yellow bibs. Like
many predators they turn out to be essential to the
survival of healthy living systems.
It now seems that many exotic species, like grey
squirrels, that appear to present intractable
problems do so only because they are moving into
depleted ecosystems. They become invasive and
destructive because there is nothing left to
restrain them. American mink, for example, are a
major problem in Europe where there are no otters,
proliferating rapidly and wiping out water voles,
birds and other species. But when otters, which are
highly territorial, move in, they drive the mink
out. White-tailed eagles, which have recently been
reintroduced to the Hebrides, but once lived
throughout Britain, prey heavily on mink and, according
to a study in Finland, keep them out of areas
they would otherwise occupy.
There might be no grey squirrel problem – in fact
there might be no grey squirrels here at all – had
pine martens not been eliminated across most of
their range, primarily by gamekeepers.
If you love grey squirrels, look away now, for
Ireland has become a bloodbath. The North American
rodents that once occcupied the whole island east of
the River Shannon are now in full-scale rout, and
the reds are pouring into the territory they have
abandoned. While until recently the greycoats looked
invincible everywhere, in around 20 years the
frontier has
shifted 100km to the east. At this rate, in
another 20 years the last of them will have been
driven into the Irish Sea, and Ireland will have
been reclaimed by the reds. (No political metaphor
is intended).
So what’s going on? Well it now seems that the
reason why grey squirrels never got past the Shannon
is not that they couldn’t cross the river. They can
swim, and there are plenty of places in which they
could move through the trees without getting their
feet wet. It’s because the far side of the Shannon
was pine marten territory. And pine martens love
grey squirrels – in the strictly carnal sense.
Red squirrels have a simple adaptation to pine
martens: they are small and light enough to get to
the ends of the branches, where the martens can’t
follow. But grey squirrels, which did not co-evolve
with these predators, are, by comparison, lumps:
slower and heavier than the native species. They are
also more terrestrial than the reds: in other words
more dependent for their survival on foraging on the
woodland floor. Meals on legs, in other words.
As people in Ireland have mostly stopped killing
pine martens, which are now legally protected, they
have begun to recolonise their former ranges. And
the grey squirrels appear to have vanished into thin
air. You have to read the
paper published on this phenomenon last year
to believe just how rapid and comprehensive this
process has been. But you probably won’t, so here
are some extracts.
“The grey squirrel population has crashed in
approximately 9,000 km2 of its former range and the
red squirrel is common after an absence of up to 30
years.”
“Grey squirrel sightings accounted for less than 8%
of animal sightings in [the Irish Midlands], which
is remarkably low considering that they are a much
less elusive species than either the red squirrel or
the pine marten, and are also more commonly
associated with human settlements.”
The health and weight of grey squirrels in the pine
marten zone is “extremely poor”, while squirrels in
an area without martens “are thriving”.
“This is the first documented evidence of a grey
squirrel population retracting, without any human
intervention, subsequent to having established
itself as an invasive species.”
Two aspects of this story jump out at me. The first
is the greys’ astonishing speed of retreat. The
numbers just don’t add up: the martens simply
couldn’t eat that many squirrels. As the paper
points out “it would be unlikely that a low density
pine marten population could impact a high density
grey squirrel population by direct predation alone.”
The second is that grey squirrels in the region
haunted by pine martens are much thinner than those
elsewhere. At first sight this makes no sense: with
fewer competitors, you would expect the survivors to
be fatter and healthier.
So what’s going on? Though the paper doesn’t
speculate, there seems to be a likely explanation.
The pine martens are creating a “landscape of fear”,
rather like the
one that some ecologists (though others
have now challenged the claim) believe wolves
have generated among deer in the Yellowstone
National Park. It’s not just that pine martens are
eating the squirrels: they are terrifying the living
daylights out of them.
If grey squirrels have no defences against martens,
they must spend much of the time they would
otherwise have spent feeding trying to avoid them.
They are likely – metaphorically or perhaps
literally – to spend so much time looking over their
shoulders while they should be foraging during the
summer that they don’t accumulate sufficient fat to
get through the winter. The pine martens are
starving them out.
The lesson is obvious – to everyone except the
dunderheads administering public policy in Britain.
If, as they claim, their aim is to eliminate grey
squirrels, rather than to pour money into the laps
of the landed gentry, they should abandon the
useless programme of trapping, shooting and
poisoning, and instead bring back a native predator.
While pine martens are once again thriving in parts
of Scotland (and, surprise, surprise, these are the
places in which red squirrels also survive and grey
squirrels are absent), across England and Wales they
are functionally extinct. This means that while
there are some tiny remnant populations in a few
areas (Cumbria, Snowdonia and the North York Moors
for example), due to intense persecution by
gamekeepers and others in the past their genetic
base is too narrow to allow them to expand.
Re-establishing pine martens means reintroducing
them: bringing new genetic stock both to the pockets
in which they survive and to places from which they
have been eradicated. That is what the Vincent
Wildlife Trust, among others, hopes
to do.
Meanwhile, the Game and Wildlife Conservation
Trust, which I see as a greenwashing agency for the
shooting industry (how many conservation groups do
you know that teach
children to use shot guns and run
courses on snaring, lamping and trapping?), is
lobbying
to reduce pine marten populations in Scotland.
Yes, reduce.
It claims that it wants to do so to protect
capercaillies: the giant grouse that also once lived
across much of Britain but are now confined to a few
glens in Scotland. But there is no evidence that
pine martens are implicated in the capercaillie’s
decline: in fact the capercaillie is doing best
where pine martens are also thriving, and doing
worst where the predator continues, illegally, to be
persecuted.
(I wonder whether there might be a connection?
Might pine martens suppress other predators that
affect capercaillies? Or are both species victims of
the appalling land management practised by
“sporting” estates in areas like Deeside?)
The Game and Wildlife Conservation Trust’s attitude
is typical of the views that have long prevailed
amongst shooting interests: all too often estate
owners would rather cut their own throats than
tolerate the presence of predators, even when those
predators are protecting them from massive problems,
like grey squirrels or (due to the absence of lynx)
exploding roe and sika deer populations.
Unfortunately, it is these entrenched interests and
entrenched attitudes that still dominate government
policy. The futile plan to cull grey squirrels was
hatched at a symposium of chinless wonders convened
by the Prince of Wales and Owen Paterson in
one of Charles’s many properties, Dumfries House in
Scotland.
This meeting took place several months after the
Irish study was published. But the British
Establishment is almost impervious to new thinking
and new information, so perhaps it’s unsurprising
that this confederacy of dunces decided to pour
millions into a futile gesture, rather than to do
something useful. I dare say that most of them still
regard pine martens as vermin anyway.
Like the army and navy in the 18th century, the
governance of the countryside is still dominated by
titled amateurs, while those with professional
knowledge and expertise are frozen out.
So perhaps there is a political metaphor here after
all. Isn’t it time that these grey and ponderous
relics of the Victorian era were pushed out of
policy-making, and replaced by bright-eyed and
bushy-tailed people who are agile enough to respond
to new situations?
www.monbiot.com
