don't fear the beaver
TRANSCRIPT
●IT TOOK years of research and
planning, but finally everything was
ready. After an absence of at least 200
years, beavers looked set to return to mainland
Britain, one of the final frontiers in their
reintroduction across Europe. The plan –
the brainchild of Scottish Natural Heritage –
was to release them into a secluded valley in
Knapdale forest in the west of Scotland and see
how they got on. Popular support was strong
but last-minute lobbying from powerful local
landowners resulted in the Scottish Executive
refusing permission in 2005. Once again, it
seemed, these shy herbivores had fallen foul
of their reputation for eco-destruction.
Beavers are no strangers to opposition. In
this case, the landowners feared they would
damage valuable salmon stocks in local rivers.
Beavers don’t eat fish – though plenty of
people think they do – but the landowners
42 | NewScientist | 25 August 2007 www.newscientist.com
Cursed with a reputation for destruction, the beaver’s tale is an unhappy one. But we are finally seeing an eco-saint where once we saw a sinner, says Gail Vines
Don’t fear the beaver
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mistakenly imagined their dams would cause
problems. It’s an old, misbegotten story.
The beaver’s penchant for hydrological
engineering has brought it into conflict with
people across Europe and North America for
centuries, so it’s no small irony that experts
are now realising that this is exactly why we
need beavers in our countrysides.
“They are the quintessential ecosystem
engineers,” says ecologist James Byers at the
University of New Hampshire. “And they’ll do
this work for free.” Beaver-built waterworks
not only create habitats for wildlife, they
also boost water quality and reduce the twin
threats of drought and flooding. In fact, the
beaver could even be an invaluable ally in
battling the effects of climate change.
Pursued for centuries by hunters keen to
transform their pelts into luxury waterproof
hats, beavers were probably saved from
extinction only by a change of fashion in the
1840s. By the beginning of the 20th century,
tiny populations of the European beaver,
Castor fiber, survived in just a few rivers in
Russia and southern Norway, in the Rhone in
France and the Elbe in Germany. Meanwhile,
across the Atlantic, the closely related North
American species Castor canadensis clung
on only in Canada’s remote boreal forests.
Today, both species are steadily recolonising
their original ranges across North America
and Europe, through a combination of
natural spread and reintroductions. Now
re-established in 26 European countries,
beavers are missing from only a handful
including Italy, Greece, Albania, Macedonia
and mainland Britain (there is no evidence
that beavers have ever lived in Ireland).
“The reintroduction of the beaver in
Europe has been an outstanding success,” says
Andrew Kitchener, principal curator of
mammals and birds at National Museums
Scotland in Edinburgh. Immensely adaptable,
they feed on a wide range of herbaceous
plants and can set up home in almost any
freshwater environment. In small waterways,
they construct dams of mud and timber to
raise water levels and create ponds in which
they can then build a safe shelter, or lodge, cut
off from the shore and with only underwater
entrances . In larger rivers, however, they
dispense with the lodge and burrow into the
bank instead, becoming virtually invisible to
unsuspecting humans.
Dams built by beavers are recreating Europe’s lost wetlands after centuries of destructive drainage
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where beavers were reintroduced in the 1960s,
there is a team of beaver wardens licensed to
trap and remove “problem beavers”.
In North America too, where beavers
have even more of a reputation as a nuisance,
“proactive management” is encouraging
people to learn to live with them. One useful
tool is the “beaver deceiver”, a perforated
plastic pipe that beavers find impossible
to plug up. Inserted into an inconvenient
dam, beaver deceivers create permanent
leaks which keep water levels at a chosen
maximum. Another device, essentially a
sturdy wire-mesh cage, prevents beavers
blocking culverts and flooding roads. Trees
can be protected by wrapping them in wire
mesh, or by coating tree trunks with a sand-
rich paint. In the future, chemical repellents
containing extracts from unpalatable plants
may do the job.
Instant wetlandsAccepting beavers as neighbours is one thing,
but many experts now believe we should be
actively promoting their spread into their
former ranges. For a start, they say, beavers
bring ecological benefits by creating ponds
upstream of their dams – instant wetlands
recreating those destroyed through centuries
of drainage campaigns.
In Canada, ecologists have discovered that
mapping beaver ponds by remote sensing
is the best way to monitor amphibian
populations – the frogs and toads can
barely survive anywhere else ( New Scientist,
11 January ). In the Adirondack mountains of
New York, the wetland habitats created by
beavers along river banks are rich in plants
found nowhere else. In Alaska, a remarkable
diversity of mosses find homes in beaver
“meadows” – micro-landscapes of pits and
hummocks formed on the site of abandoned
beaver ponds. Beaver “ghost towns” are also
a familiar feature in these wetlands because
beavers move along when their preferred
food plants are depleted, allowing vegetation
to regenerate. In the process they become
agents for renewal, helping to create dynamic,
biodiverse landscapes.
It could be a similar story in those places
where beavers remain unwelcome. “Beavers
would create habitats suitable for up to
32 species in need of urgent conservation
action,” says Rob Strachan of the UK’s
Environment Agency. “Critics ask, ‘Why put
money and time into bringing back one
species?’” says Martin Gaywood of Scottish
Natural Heritage. “But when it comes to this
keystone species, lots of animals and plants
benefit too – it’s extremely cost-effective
conservation.”
“I’m sold on the ecological benefits, and
13th tee. Nearby in the same park, another
beaver family has built its lodge by a popular
jogging and dog-walking trail, within spitting
distance of a picnic table. “In Norway, people
generally accept the animals as part of the
landscape and leave them alone to get on with
their lives,” says Duncan Halley, an ecologist at
the Norwegian Institute for Nature Research
in Trondheim.
Halley has studied the beaver families in
and around the city and has come across little
conflict with local communities. Managers
at the lakeside golf course have taken the
precaution of wrapping chicken wire around
a few attractive birch trees close to the shore.
“It’s a simple and effective way of protecting
trees,” says Halley. Any troublesome dams or
animals can be removed. A similarly flexible
management strategy has been adopted
elsewhere in Europe. In Bavaria, for example,
Beavers do not just thrive in wilderness
either: they are pragmatic about people and
can now be found in downtown Vienna, for
example. Beavers also live in the Netherlands,
one of the most densely populated countries
in the world, where they are celebrated as a
symbol of natural restoration – the Dutch
equivalent of the panda. In Denmark, visitors
flock to Klosterheden, dubbed “Beaverland”,
to spend the night in outdoor shelters and
watch the animals at dusk and dawn. “It is
very difficult to keep up with demand – the
interest in guided tours is enormous,” says
conservationist Olivier Rubbers.
In Norway, where beavers never went
extinct, people take them for granted. On
a visit to Trondheim, I watched a beaver
paddling about nonchalantly while its partner
nibbled birch twigs on the lakeside beside a
golf course. Their lodge was right next to the
44 | NewScientist | 25 August 2007 www.newscientist.com
Furry pioneersOur ancestors survived by outsmarting
the wildlife – or so we imagine. But
what if we humans were actually
utterly reliant on a chunky fellow
mammal with a scaly flat tail? A radical
new study has revealed the lost history
of human co-evolution with beavers.
“Landscapes altered by beavers
offered virtually everything people
needed,” says Bryony Coles, an
archaeologist at the University of
Exeter, UK. Thanks to beavers, she
believes that prehistoric humans
had easy access to pre-cut timber
for building and firewood, and rich
hunting sites. Perhaps, says Coles, we
even learnt coppicing from beavers.
It was 1978 when Coles came across
some odd-looking pieces of wood at
the Neolithic “Baker platform”, built
about 6000 years ago on the edge
of ancient marshes in the Somerset
Levels, UK. Within the wooden
platform were pieces of willow,
covered in puzzling cut marks unlike
anything produced by Neolithic tools.
To test a hunch, the archaeologists
asked Chester Zoo to send down a
parcel of beaver-gnawed wood. “As
soon as we opened it, we knew for
sure,” Coles says: her find was beaver-
cut timber, appropriated by Neolithic
builders as easy building material. So
was born a fascination with beavers
that culminated three decades later
in her book Beavers in Britain’s Past (Oxbow Books, 2006).
After the last ice age, humans
and beavers both recolonised Britain
around 9500 BC. Coles found that for
the early settlers, beaver-grazed banks
supplied coppiced woodlands, while
their ponds were perfect hunting
grounds for fish, birds and mammals.
Beaver dams served as convenient
causeways, and the channels they
dredged were forerunners of our
irrigation ditches.
From about AD 1200, as human
exploitation of river systems
intensified, beavers slowly began
to disappear. “The loss of beaver
habitat was probably so gradual and
imperceptible that few people noticed
what was gone, or realised that
coppices, fishponds, water meadows
and causeways were not innovations
but replacements,” says Coles. The last
beavers in Britain may have survived
into the late 18th century in Yorkshire,
Coles suspects. “People have lived in
Britain without the presence of beavers
probably for no more than four or five
human generations.”
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the benefits to biodiversity, not least to water
voles and otters,” adds Alastair Driver of the
UK’s Environment Agency. He is dismayed
that beaver introductions have been
scuppered by arguments that they would
damage aquatic ecosystems, salmon stocks
in particular. A recent study along one
Norwegian river fully colonised by beavers
shows that salmon rarely even encountered
them. In fact, in Scandinavia, beaver ponds
actively benefit the closely related sea trout,
says Bror Jonsson of the Norwegian Institute
for Nature Research. Their dam s store water
to support young trout during droughts and
help to neutralise acidic surface waters
( River Research Applications, vol 23, p 1 ).
It is not just conservationists who are keen
to extend the reintroduction of beavers. There
are real economic benefits, too. Coppicing
willows along river banks costs a lot of
money – up to £11,000 per hectare in the UK –
and has to be repeated every decade. “Farmers
used to manage all those river edges but not
any more, so we’re in danger of losing all these
wet habitats to woodland,” says Jonathan
Spencer of the Forestry Commission. “Beavers
would manage our wet woodlands for us – and
we wouldn’t even have to pay them.”
Not only that, beaver dams are highly
effective silt traps, purifying rivers that would
otherwise carry damaging sediment loads. On
the Sumka river in Russia, one study found
that a series of three beaver dams trapped
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4250 tonnes of sediment from agricultural
erosion in a single year, halving the sediment
load. In Brittany, France, agricultural
discharge, including eroded soil and fertilisers,
was slashed by 90 per cent in beaver-dammed
streams. And their “ecosystem services” don’t
stop at water purification. Beaver dams and
lodges are also “deadwood jungles” – paradise
for the aquatic invertebrates that are vital to
the freshwater food chain. “For many decades
we’ve stripped everything from rivers, all the
debris and submerged timber, but now we’re
having a major rethink,” says Spencer.
“If there’s one thing that’s good at putting
deadwood into rivers, it’s beavers.”
There’s so much more. Beaver dams slow
water run-off during periods of both flooding
and drought. Hydrologist Cherie Westbrook of
the University of Saskatchewan in Saskatoon,
Canada, studies the impact of beavers on the
movement of water through river systems.
One of her projects, in Colorado’s Rocky
mountains, stretched over three years,
including one of the wettest on record and two
of the driest. “Beavers have a massive effect in
drought, with a fantastic ability to move water
round the landscape” and compensate for low
levels, she explains.
Westbrook is now investigating how
beavers in the Canadian Rockies store water
in watersheds and gradually release it into
streams: each beaver pond retains water
behind its dam, but they flow into one another
“like a series of leaky buckets”, she says.
In the UK, people are beginning to grasp
the benefits of beavers but many are still
uneasy about letting them loose in the
countryside. “There’s a fear that once the
genie is out of the bottle there’s no going
back,” says Peter Holmes of Natural England.
“In fact, beavers are very easy to control.”
Conservationists believe that following the
European beaver warden model would readily
resolve disputes.
While officialdom may quail at the
prospect of beavers in the wild, enthusiastic
British landowners are already bringing
beavers onto their land – albeit behind fences.
In Banff, Perthshire, Paul Ramsay showed me
around his estate, where two beaver families
are established. The lake-dwellers live quietly,
sustained mostly by corms and aquatic plants
such as the yellow flag iris, while the stream-
dwellers have got to work cutting birch and
grey alder for dams to raise water levels. In the
process, they are recreating the wildlife-rich
wetland that Ramsay’s ancestors drained
away. The project has been a labour of love for
Ramsay – and cost him a fortune in fencing.
“It’s a shame beavers in Britain have to be
kept in enclosures at the moment,” says Derek
Gow, another independent conservationist
based in Devon. “But at least it enables people
to see that this is not some Godzilla-like
animal that will knock over double-decker
buses and bring an end to civilisation.”
He and others continue to campaign for
the reintroduction of beavers, and there
are signs that success may not be far off.
Scotland’s new environment minister
Mike Russell is strongly in favour of a trial
reintroduction.
Arguments that beavers damage the
environment are becoming increasingly
unsupportable. In fact, it is now emerging that
they may have been crucial to the survival of
Neolithic people colonising new lands, such
as the recolonisation of Great Britain after the
last ice age around 11,500 years ago (see “Furry
pioneers”, left). What is more, according to
Bryony Coles at the University of Exeter,
UK, who has documented ancient peoples’
dependence on beavers, the time is rapidly
coming when we may have to rely on them
again. As increasing numbers of us around
the globe face floods and drought as a
consequence of our own environmental
mismanagement, the engineering skills of
beavers may prove invaluable. “There are
pressing and selfish reasons why we should
reinstate them,” she says. ●
Further reading: Beavers by Andrew Kitchener, Whittet Books (2001); The Beaver: Natural history of a wetlands engineer by Dietland Muller-Schwarze and Lixing Sun, Cornell University Press (2003)
The beaver is a keystone species, whose presence benefits dozens of others
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“ Beavers are the quintessential ecosystem engineers, and they do all the work for free”
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