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 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.
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“Beavers are the quintessential ecosystem engineers, and they do all the work for free”
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.
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 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, 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 wetlands
Accepting 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 (鶹ý, 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 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 ().
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 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 Bamff, 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”). 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.
Furry pioneers
Our 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.”
