don't fear the beaver

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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 ROGER TIDMAN/NHPA

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Page 1: Don't fear the beaver

●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

ROGE

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/NHP

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Page 2: Don't fear the beaver

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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www.newscientist.com 25 August 2007 | NewScientist | 43

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Page 3: Don't fear the beaver

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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Page 4: Don't fear the beaver

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

www.newscientist.com 25 August 2007 | NewScientist | 45

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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